Blog – Aquahorti.com: Meters, Controllers, and Lights for Aquarium & Horitculture

Growing Green Onions in a Greenhouse:

What PAR, CO₂, and VPD Taught Me About Speed, Texture, and Regrowth Green onions (scallions) look simple. They grow fast, tolerate cutting, and seem much less fragile than lettuce. Because of that, I originally treated them as a “low-attention” crop. That assumption didn’t last long. Once I started growing green onions seriously in a greenhouse—and […]

Growing Wheatgrass and Chives in a Greenhouse: What PAR, CO₂, and VPD Taught Me About Two “Simple” Crops That Behave Very Differently

At first glance, wheatgrass and chives seem easy.They grow fast, look sturdy, and are often labeled as beginner crops. But once I started growing both in the same greenhouse — and actually tracking PAR, CO₂, and VPD instead of guessing — I realized how different their needs really are. They may look similar from above, […]

Growing Bok Choy in a Greenhouse: What PAR, CO₂, and VPD Taught Me About Fast Crops and Fragile Balance

Bok choy looks like a forgiving crop.It grows fast, it looks sturdy, and on paper it tolerates a wide range of conditions. Because of that, I initially treated it as a “set it and forget it” leafy green. That assumption didn’t last long. Once I started measuring PAR, CO₂, and VPD instead of relying on […]

Growing Mustard Greens in a Greenhouse:

What I Learned About PAR, CO₂, and VPD by Actually Growing Them I used to think mustard greens were almost “foolproof.” They grow fast, they tolerate cold, and they don’t look demanding on paper. But once I started growing them seriously in a greenhouse — and measuring PAR, CO₂, and VPD instead of guessing — […]

Growing Tarragon in a Greenhouse:

What I Learned About PAR, CO₂, and VPD Through Trial and Error Tarragon taught me a lesson that many other herbs didn’t:you can’t force it. When I first grew tarragon in a greenhouse, I treated it like basil or rosemary. I increased light, dried the air slightly, and expected faster growth. Instead, the plants slowed […]

Growing Tarragon in a Greenhouse:

What I Learned About PAR, CO₂, and VPD at Each Growth Stage Tarragon looks like a simple herb, but growing it well in a greenhouse taught me a lesson I didn’t expect:tarragon hates extremes. I initially treated it like basil and rosemary — pushing light and drying the air — and the plants clearly pushed […]

Growing Chives in a Greenhouse:

How PAR, CO₂, and VPD Change Across Growth Stages (From Real Grower Experience) Chives are often described as “easy herbs,” but when I actually started growing chives in a controlled greenhouse environment, I realized how sensitive they are to light balance and humidity stress—especially if you want fast regrowth and tender leaves instead of thin, […]

PAR, CO₂, and VPD Requirements for Greenhouse Swiss Chard at Different Growth Stages

When I first started growing Swiss chard in my greenhouse, I treated it like most leafy greens: give it bright light, consistent water, and a balanced soil mix. In the early weeks that approach seemed to work well — seedlings developed leaves quickly — but as plants grew larger I began noticing pronounced differences in […]

PAR, CO₂, and VPD Requirements for Greenhouse Arugula at Different Growth Stages

When I first started growing arugula in my greenhouse, I approached it much like I did other leafy greens: give it bright light, consistent moisture, and balanced soil nutrients, and it should grow quickly. In the early weeks that approach seemed to work — seedlings developed leaves rapidly — but as plants matured I began […]

PAR, CO₂, and VPD Requirements for Greenhouse Sage at Different Growth Stages

When I first began growing sage in my greenhouse, I assumed it would be as straightforward as other Mediterranean herbs: plenty of light, well-drained soil, and moderate water should be enough. In the earliest stages that approach seemed to work — seedlings sprouted and the first aromatic leaves appeared. But as plants matured I started […]

PAR, CO₂, and VPD Requirements for Greenhouse Oregano at Different Growth Stages

When I first started growing oregano in my greenhouse, I treated it like most other Mediterranean herbs I had grown: give it plenty of light, moderate water, and well-drained soil, and it will thrive. In the first few weeks, seedlings developed quickly and leaves opened with the expected aroma. However, as plants matured, I began […]

PAR, CO₂, and VPD Requirements for Greenhouse Thyme at Different Growth Stages

When I first started growing thyme in my greenhouse, I treated it much like other Mediterranean herbs: plenty of light, modest water, and good soil structure should be enough. In the earliest stage that approach seemed adequate, but as plants matured I began seeing differences in leaf density, aroma strength, and overall growth vigor that […]

PAR, CO₂, and VPD Requirements for Greenhouse Rosemary at Different Growth Stages

When I first started growing rosemary in my greenhouse, I treated it like most herbs I’d grown before: give it light, water appropriately, and let nature take its course. In the very early stages that seemed to work — seedlings sprouted and developed their first aromatic leaves. But as the plants matured, I began noticing […]

PAR, CO₂, and VPD Requirements for Greenhouse Dill at Different Growth Stages

When I first began growing dill in my greenhouse, I treated it much like other leafy herbs: plenty of light, regular moisture, and fertile soil. In the early weeks that approach seemed to work fine — seedlings sprouted and leaves unfolded quickly. But as the plants matured, I started noticing differences in growth, leaf density, […]

PAR, CO₂, and VPD Requirements for Greenhouse Parsley at Different Growth Stages

When I first started growing parsley in my greenhouse, I treated it much like any other leafy herb: provide plenty of light, consistent water, and quality nutrients, and it should grow well. In the early weeks, seedlings seemed to respond to this approach, forming their first leaves quickly. But as parsley entered more advanced vegetative […]

PAR, CO₂, and VPD Requirements for Greenhouse Coriander (Cilantro) at Different Growth Stages

When I first began growing coriander (also known as cilantro) in my greenhouse, I assumed it would be as straightforward as other leafy herbs: give it enough light, keep the soil moist, and it will thrive. In the earliest weeks that often held true, but as plants grew larger I began noticing differences in leaf […]

PAR, CO₂, and VPD Requirements for Greenhouse Peppermint at Different Growth Stages

When I first started growing peppermint in my greenhouse, I treated it like most herbs: lots of light, moist soil, and balanced nutrients should be enough. In the early weeks seedlings looked healthy, but as the plants matured I began noticing differences in leaf size, aroma strength, and overall vigor across different parts of the […]

PAR, CO₂, and VPD Requirements for Greenhouse Basil at Different Growth Stages

When I began growing basil in my greenhouse, I treated it as I did other herbs: plenty of light, regular watering, good soil, and it should flourish. In the first couple of weeks that seemed true — seedlings sprouted and the first sets of true leaves formed quickly. But once the plants grew larger, differences […]

PAR, CO₂, and VPD Requirements for Greenhouse Spinach at Different Growth Stages

When I first started growing spinach in a greenhouse, I treated it much like I did other leafy greens: give it bright light, steady water, and a healthy soil mix. For the first few weeks, seedlings grew quickly and leaves unfurled as expected. But as plants progressed into larger vegetative growth, I began noticing differences […]

PAR, CO₂, and VPD Requirements for Greenhouse Kale at Different Growth Stages

When I first started growing kale in a greenhouse, I treated it much the way I did other leafy greens: provide bright light, consistent water, and balanced nutrients, and the plants should thrive. In the beginning that seemed sufficient — seedlings unfolded and leaves looked healthy — but as the plants matured I began to […]

PAR, CO₂, and VPD Requirements for Greenhouse Lettuce at Different Growth Stages

When I first started growing lettuce in a greenhouse, I approached it much like my other crops: give them light, water, and nutrients, and they should grow quickly. In the beginning that seemed true — seedlings developed and leaves unfurled — but as plants neared full size I began noticing inconsistent leaf density, slow head […]

PAR, CO₂, and VPD Requirements for Greenhouse Strawberries at Different Growth Stages

When I first started growing strawberries in a greenhouse, I treated them the way I did most fruits: good soil, regular water, and plenty of light should be enough. In the early weeks that seemed to work, but as plants entered flowering and fruiting stages I began noticing inconsistent bloom set, variation in fruit size, […]

PAR, CO₂, and VPD Requirements for Greenhouse Cucumbers at Different Growth Stages

When I first began growing cucumbers in my greenhouse, I assumed that light and water were the main variables to manage. I gave them strong sunlight, balanced irrigation, and typical fertilizer, expecting vigorous vines and plentiful fruit. Early on, that approach produced decent growth, but as plants matured I saw inconsistent flowering and fruit development […]

PAR, CO₂, and VPD Requirements for Greenhouse Tomatoes at Different Growth Stages

When I first transitioned from casual container gardening to growing tomatoes in a greenhouse, I approached it the same way I had treated other plants: give them plenty of light, water, and nutrients, and they should thrive. For the first few weeks that worked well, but as the plants matured I began seeing inconsistency in […]

CO₂ Requirements for Plants at Different Growth Stages

When I first started monitoring plant growth more closely, I paid most of my attention to light and water. Carbon dioxide (CO₂) was something I thought only mattered in high-tech greenhouses or commercial operations. Over time, as I tracked plant performance alongside environmental data, I began recording CO₂ levels and noticing patterns that couldn’t be […]

Why It’s Important to Record CO₂ PPM in Growing Environments

When I first started growing more light-demanding plants — tomatoes, peppers, leafy greens — I focused most of my attention on light, water, and fertilizer. Carbon dioxide (CO₂) was something I thought only mattered in industrial greenhouses or commercial facilities. It wasn’t until I began seeing inconsistent growth in spaces with otherwise similar light and […]

The Relationship Between PAR, CO₂, and VPD in Plant Growth

When I first started paying attention to light measurement for my plants, I focused almost exclusively on PAR — Photosynthetically Active Radiation, the amount of usable light plants receive in the 400–700 nm range. Over time, as I started experimenting with greenhouse crops and more controlled environments, I realized that light is only one piece […]

Why Some Smartphone PAR Measurement Apps Require Extra Purchases

When I first started measuring light for my plant collection, I naturally looked for the simplest tools available. My smartphone was always with me, and I downloaded a few light meter apps that claimed to estimate PAR (Photosynthetically Active Radiation). Many of these apps worked fine for a few measurements, but soon I encountered “premium” […]

Why Smartphone Cameras Must Use Different Light Modes to Estimate PAR

When I first started using a smartphone to estimate light for my plants, I quickly discovered that the camera’s standard settings were not enough. I would point my phone toward a grow light or near a window, and the default camera view would show one set of brightness values. At the same time, a “night” […]

Why Smartphone Camera–Based Light Measurements Struggle With Red-Blue Grow Lights and Reflective Grow Spaces

When I first started experimenting with grow lights for my indoor plants and seedlings, I naturally reached for the tools I already had at hand — primarily my smartphone’s light meter apps and the camera. I assumed that if the phone said a spot was bright, the plants would be getting plenty of usable light. […]

Understanding the Spectral Response of Smartphone Camera Sensors

For years I used my smartphone camera and light meter apps to gauge how much light my plants were getting. It seemed straightforward: open the app, point the camera at the light source or plant canopy, and get a number. If the number was high, I assumed the plant had enough light. If it was […]

Smartphone-Based Light Meter Solutions — An Objective Analysis

For years I relied on smartphone apps to gauge light conditions for my plants. With a quick glance at the screen, I would tell myself that a spot was “bright enough” or “too shaded” and make planting decisions accordingly. My library of plant books reinforced that approach: “full sun,” “partial shade,” “bright indirect” — all […]

Ficus lyrata Light Requirements: PAR & DLI for Different Growth Stages

When I first brought a Ficus lyrata into my home, I treated light the way I did for other popular houseplants: place it near the brightest window available and assume it would thrive. Some fiddle leaf figs did well, but others developed leggy stems, smaller leaves, or uneven growth even when they were in equally […]

Sansevieria trifasciata Light Requirements: PAR & DLI for Different Growth Stages

When I first started growing Sansevieria trifasciata (commonly known as snake plant), I treated light like many caretakers do for tough houseplants: bright is good, shade is fine, and survival seems easy. Early on, my snake plants survived almost anywhere — hallways, bathrooms with little light, and bright window sills. But I began noticing clear […]

Epipremnum aureum Light Requirements: PAR & DLI at Different Growth Stages

When I first started growing Epipremnum aureum (commonly called pothos), I assumed light was not something I needed to think much about. The plant survived almost everywhere — shelves, corners, offices, even rooms far from windows. But over time, I noticed clear differences. Some plants grew dense and full with large leaves, while others produced […]

Monstera deliciosa Light Requirements: PAR & DLI at Different Growth Stages

When I first brought Monstera deliciosa into my home, I treated light the same way I did for most houseplants: place it in a bright spot near a window and hope it thrives. Some plants did well, but others developed long stems, smaller leaves, or slower growth even in seemingly sunny positions. That inconsistency made […]

Kalanchoe Light Requirements: PAR & DLI at Different Growth Stages

When I first started growing kalanchoe, I treated light the way I treated most succulents: place them where it looked bright and assume they would thrive. In some cases that worked well, but I also had plants that became leggy, produced fewer blooms, or developed stretched and pale leaves despite being in spots that looked […]

Aloe Light Requirements: PAR & DLI for Different Growth Stages

When I first began growing aloes, I treated light much the way many gardeners do: bright spot near a sunny window or in full garden sun should be enough. Some plants stayed compact and healthy, while others stretched, lost their rich color, or became floppy despite being in seemingly similar bright spots. That inconsistency made […]

Sempervivum Light Requirements: PAR & DLI by Growth Stage

When I first started growing sempervivums — the hardy little rosette succulents many gardeners call hens and chicks — I treated light the same way I did for other sun-loving plants: find the brightest spot and hope for the best. Some plants did great, producing tight, colorful rosettes, while others became loose, stretched, or pale […]

Jade Plant (Crassula ovata) Light Requirements: PAR & DLI by Growth Stage

When I first started growing jade plants, I treated light the same way I treated most succulents: place them in a bright window and assume they would be fine. At first, that seemed to work. Some plants looked healthy and compact while others in equally bright spots grew stretched, pale, or leggy. It made me […]

Jade Plant Light Requirements: PAR & DLI at Different Growth Stages

When I first started growing jade plants (Crassula ovata) at home, I treated light the same way I treated most succulents: a bright window seemed enough. Early on, some plants thrived while others became leggy, developed pale leaves, or dropped lower foliage. That inconsistency made me realize that light quality and quantity are more subtle […]

Echeveria Light Requirements: PAR & DLI for Different Growth Phases

When I first started growing echeverias, I treated light the way I had for other succulents: put them where it looked bright and trust that they would flourish. Some did well, but others developed stretched stems, faded coloration, or elongated leaves despite seeming to be in a bright spot. That inconsistency made me start measuring […]

PAR & DLI Requirements for Sedum at Different Growth Stages

When I first started including sedums in my garden designs, I treated them like many other succulents: plant them in a sunny spot and expect them to thrive. In some areas this worked perfectly, but in others the plants looked stretched, produced weaker foliage, or bloomed less reliably than I expected. That inconsistency led me […]

PAR & DLI Requirements for Geraniums at Different Growth Stages

When I first planted geraniums in my garden and containers, I treated light the same way I treated most flowering annuals: put them in the brightest spot available and assume that was enough. At first, that seemed reasonable. Yet over a couple of seasons I noticed a pattern: some geraniums produced abundant blooms and sturdy […]

PAR & DLI Requirements for Petunia at Different Growth Stages

When I first began growing petunias, I treated light the same way I treated most annual flowers: plant them in the sunniest spot I had and trust that they would flourish. At first, that seemed to make sense. But over a few seasons, I noticed that some petunias in seemingly equally bright spots looked lush […]

Understanding PAR and DLI Requirements for Holly (Ilex spp.)

When I first planted holly shrubs in my garden, I assumed they would simply grow wherever there was “enough sun.” I treated light as a basic checklist item rather than something that required measurable understanding. After a couple of seasons, I began to notice patterns that didn’t make sense. Some hollies in seemingly bright spots […]

Understanding PAR and DLI Requirements for Boxwood (Buxus spp.)

When I first added boxwoods to my garden, I treated light like a generic requirement: plant them where there is sun and they should grow. What I discovered over a few seasons was that boxwoods don’t respond to light the same way sun-loving vegetables or even many ornamentals do. Some plantings looked lush and compact, […]

Understanding PAR and DLI Requirements for Variegated Plants

When I first started growing variegated plants, I assumed that light needs were simply about brightness: more light would enhance the variegation, less light would dull it. Over multiple growing seasons, I discovered that this assumption was too simplistic. Some variegated plants in what looked like bright spots developed pale or washed-out leaves, while others […]

Understanding PAR and DLI Requirements for Oxalis Triangularis (Purple Shamrock)

When I first introduced Oxalis triangularis — commonly called purple shamrock — into my plant collection, I treated its light needs the way I did for most other houseplants: bright spot near a window seemed enough. Some plants thrived, but others developed pale leaves or grew leggy without the vibrant deep purple color I expected. […]

Understanding PAR and DLI Requirements for Orchids

When I first started growing orchids at home, I treated light the same way I did for most other plants: a bright window should be enough. Some orchids did reasonably well, but others developed thin, pale leaves, or refused to bloom. What puzzled me most was that even spots that looked equally bright sometimes produced […]

Understanding PAR and DLI Needs for African Violets

When I first started growing African violets, I treated light the way I had for other houseplants: put them in the brightest spot I had and hope they thrive. Some did okay, but others developed pale leaves or elongated stems. That inconsistency made me wonder whether light quality and duration mattered more than I had […]

Understanding PAR and DLI Needs for Cilantro (Coriander)

When I first started growing cilantro in my garden, I treated light the same way I treated most leafy herbs: bright spot equals healthy growth. At first glance, that seemed logical. But after a season of spotty growth and inconsistent plant performance, I realized that cilantro’s response to light was more nuanced than I expected. […]

PAR & DLI Requirements for Brassicas at Different Growth Stages

When I first started growing brassicas in my garden — things like broccoli, cauliflower, cabbage, kale, and Brussels sprouts — I assumed they all needed “full sun” and that was enough guidance. After a few seasons of patchy results and uneven performance, I began to wonder whether “full sun” really told the whole story. Some […]

PAR & DLI Requirements for Beets at Different Growth Stages

When I first started growing beets in my garden, I assumed they would thrive anywhere that got bright sunlight. After a couple of seasons, I began noticing patterns I did not expect. In some spots, beet plants formed lush leaf canopies but had small or misshapen roots. In other areas, roots looked decent but leaves […]

PAR & DLI Requirements for Carrots at Different Growth Stages

When I first started growing carrots, I assumed they were simple root vegetables that just needed “dirt and a bit of sun.” In practice, though, I noticed patchy growth, uneven roots, and slow development in spots that looked sunny to my eyes. That puzzle led me to measure usable light with a PAR meter and […]

PAR & DLI Requirements for Ornamental Plants at Different Growth Stages

When I first started growing ornamental plants in my garden — things like zinnias, marigolds, petunias, and salvias — I assumed light requirements were simple: either a spot got a lot of sun or it didn’t. After a few seasons, I realized that some plants in bright spots looked pale and stretched, while others in […]

PAR & DLI Requirements for Microgreens at Different Growth Stages

When I first started growing microgreens, I treated light the way I treated seedlings of other crops: as long as the tray was in a bright spot or under a grow light, it should be fine. My early trays sprouted and grew, but the stems were often long and spindly, or the leaves were pale. […]

PAR & DLI Requirements for Exotic Greens at Different Growth Stages

When I first began growing exotic leafy greens in my garden — things like Swiss chard, mizuna, tatsoi, and arugula — I assumed light requirements would be similar to those of familiar greens like lettuce and spinach. Early on, I placed plants wherever there seemed to be light, and some did fine while others remained […]

PAR & DLI Requirements for Specialty Crops at Different Growth Stages

When I first began expanding my garden to include specialty crops — things like artichokes, cardoons, edible flowers, and specialty greens — I treated light the same way I had for tomatoes or lettuce. Bright spot equals good growth. The results were inconsistent. Some crops thrived, others languished in spots that “looked” equally bright. That […]

PAR & DLI Requirements for Nicotiana (Flowering Tobacco) at Different Growth Stages

When I first began growing Nicotiana in my garden, I treated it like many other ornamentals, assuming that a sunny spot would automatically mean robust growth. After a couple of seasons, I noticed some plants that lived in bright locations still looked stretched or slow to bloom, while others in slightly less bright areas flowered […]

PAR & DLI Requirements for Strawberries at Different Growth Stages

When I first grew strawberries in my garden, I treated light the way I treated other plants: bright spot equals strong growth. After a few disappointing seasons — plants that bloomed but didn’t set much fruit, or plants that grew leaves slowly despite lots of sun — I began to question that assumption. I started […]

PAR & DLI Requirements for Parsley at Different Growth Stages

When I first started growing parsley, I treated it like many other leafy herbs and assumed that as long as it got “plenty of light,” it would grow well. After measuring usable light in different parts of my garden with a PAR meter and watching how parsley responded over time, I realized that parsley’s light […]

PAR & DLI Requirements for Mint at Different Growth Stages

When I first started growing mint in my garden, I assumed it would thrive anywhere that looked bright enough. I quickly learned through both success and failure that light matters in specific ways. Some spots that looked sunny produced leggy, pale mint, while others with moderate light produced dense, aromatic leaves. That inconsistency led me […]

PAR & DLI Requirements for Basil at Different Growth Stages

When I first began growing basil, I assumed it had similar light needs to other herbs like parsley and mint. I quickly learned that basil is more demanding. In early experiments, I planted basil in spots that “looked bright enough,” but the plants often stretched, developed pale leaves, or produced few flowers. That mismatch between […]

PAR & DLI Requirements for Kale at Different Growth Stages

When I first started growing kale, I treated light like a simple checkbox: either the spot got sun or it didn’t. After several seasons of measuring usable light with a PAR meter and watching how kale responded, I learned that kale’s light needs change as the plant grows. Young leaves, expanding foliage, and mature harvestable […]

PAR & DLI Requirements for Spinach at Different Growth Stages

When I first began growing spinach in my garden, I treated light as a simple yes-or-no condition: either it was sunny enough, or it wasn’t. Over time, as I measured usable light with a PAR meter and noted how plants responded, I learned that spinach actually has distinct light needs at different stages of growth. […]

PAR & DLI Requirements for Lettuce at Different Growth Stages

When I first began growing lettuce, I treated light in a very basic way: more sun must be better. Over several seasons of observing plants and measuring light in different parts of my garden, I came to realize that lettuce responds to light in specific ways at different stages of growth. Early leaf development, head […]

PAR & DLI Requirements for Peppers Across Growth Stages

When I first began growing peppers, I assumed they had the same light needs as tomatoes — just give them as much sun as possible and they will flourish. After measuring light across my garden and watching how peppers responded over several seasons, I learned that peppers have distinct light requirements at different growth stages, […]

PAR & DLI Requirements for Cucumbers at Different Growth Stages

When I first started growing cucumbers, I treated light like a basic assumption: bright spot equals good growth. After a few seasons of measuring light with a PAR meter and watching how plants responded, I learned that cucumbers have distinct light needs at different stages, and understanding both PAR and DLI helped me make better […]

PAR & DLI Requirements for Tomato Plants at Different Growth Stages

When I first started growing tomatoes, I treated light as if more was always better. I planted seedlings in the brightest spot I had and hoped for the best. A few weeks in, I realized that not all stages of tomato growth responded the same way to light. The plants in my garden showed that […]

PAR, DLI, and CO₂ — The Three Pillars of Plant Growth

When I first started trying to optimize my garden, I focused almost entirely on sunlight. I thought light was light — more of it must be better. I learned early on about PAR (Photosynthetically Active Radiation) and DLI (Daily Light Integral) and began measuring them in different parts of my yard. Then I added a […]

What Is ePAR — And Why It Might Replace PAR in the Future

When I first started using light meters in my garden, I focused almost entirely on PAR measurements. I stepped outside with a meter in hand, took a reading, and made decisions based on that number. At the time, it seemed like the right approach — plants need usable light, and PAR tells you how many […]

Why Some Plants Thrive Even with Low PAR and DLI

When I first started measuring light in my garden, I had a simple belief: more light equals healthier plants. I thought if a plant grew well, it must be getting strong light. If it struggled, I assumed the light was too weak. It didn’t take me long to realize that this assumption was too simplistic. […]

Understanding DLI Across the United States: Why Location Matters for Light Management

When I first started gardening in different parts of the United States, I was surprised by how much light conditions varied from place to place. I assumed that “sun” meant roughly the same thing whether I was in the desert Southwest, the Midwest plains, or the cloudy Pacific Northwest. I learned the hard way that […]

What happens when DLI is technically “sufficient,” but peak PAR never reaches the plant’s ideal range

When I first started measuring plant light, one thing that confused me was seeing daily light totals that looked “good enough,” yet plants seemed to struggle. I would check my DLI estimates at the end of the day and think: “This location has more than enough daily light. Why aren’t my plants thriving?” Eventually, after […]

Direct, Diffuse, and Reflected Light: What They Mean for Plant Growth

When I first started gardening, I treated terms like “full sun” and “partial shade” as abstract labels. The first few times I followed those classifications literally, the results varied widely. Plants placed in “full sun” spots sometimes struggled, and some in “partial shade” spots thrived more than I expected. I eventually realized that these labels […]

How to Place Plants in Your Yard Using “Full Sun,” “Partial Sun,” “Partial Shade,” and “Shade”

Why Does the PAR Curve Fluctuate Dramatically Around Noon?

When I first started measuring light in my garden, I expected the PAR curve to be smooth and predictable. I thought as the sun climbed, PAR values would simply rise and fall in a gentle arc throughout the day. What I didn’t expect was how much the PAR curve could jump up and down right […]

Why Morning PAR Rises Faster Than It Falls in the Evening

When I first started measuring light in my garden, I thought light intensity would rise and fall in a simple mirror pattern throughout the day. I expected the curve of PAR values to look symmetrical — as if morning and evening were two sides of the same hill. My measurements showed otherwise. Over many days […]

Why the Ground Rod Design Makes AH-PARDLI More Practical for Real-World Use

When I first started measuring light outdoors, I treated the meter like a delicate instrument that belonged on a shelf or at most on a table. I assumed that if I needed a reading, I would simply hold it up, take a measurement, and then put it away. That all changed the day I tried […]

Why a PAR Meter Should Withstand Rain, Wind, and Sunlight

When I first started using a PAR meter in my garden, I treated it like an indoor tool. I carried it out to take a reading and then brought it straight back inside for safekeeping. At that stage, I thought weather protection was just a nice-to-have feature, not a necessity. Over time, as I began […]

AH-PARDLI: A Bluetooth PAR Meter That Works Anywhere — No Internet Required

When I first started measuring light for my plants, I depended on apps and internet lookups to understand what a reading meant. If I couldn’t connect to Wi-Fi, the meter sat idle. That changed when I began using the AH-PAR/DLI meter, a Bluetooth PAR meter that works anywhere without needing an internet connection. This article […]

AH-PAR/DLI: The World’s First PAR & DLI Meter with Curve Recording and Data Export

When I first started measuring light in my garden, I didn’t think I would ever care about things like “curve recording” or “data export.” I was satisfied with occasional PAR readings and adjusting lights based on simple numbers. That changed when I spent one season trying to understand why plants in similar light conditions behaved […]

Why Matching Readings at 450 nm and 660 nm Don’t Guarantee PAR Accuracy

When I first started using light meters in my garden, I saw a common recommendation from a few online sources: check your readings at 450 nm and 660 nm to validate your PAR meter. At the time, I thought that made sense. After all, 450 nm and 660 nm correspond roughly to blue and red […]

Why Green Light Still Shows Up Strong in the McCree Curve

When I first started trying to understand how plants use light, I was surprised to see how strongly green light appeared on the McCree curve. For most of my early gardening, I had assumed plants only really used blue and red light. I thought green light might be mostly wasted or reflected. It took weeks […]

What Is the McCree Curve? Understanding How Plants Use Light

When I first started using a light meter and reading about plant lighting, I kept encountering something called the McCree curve. At the time, it just sounded like a scientific chart that didn’t have much to do with what I was trying to do in my backyard garden. But after weeks of measuring light under […]

Understanding μmol/s, μmol/J, and μmol/m²/s: The Language of Light for Plants

When I first started learning about plant lighting, all these units — µmol/s, µmol/J, µmol/m²/s — sounded like a foreign language. They looked technical and abstract. I remember holding a PAR meter in my hands and feeling like I needed a physics degree to decode the numbers. What finally helped me understand these terms was […]

Chlorophyll a and b: The Hidden Drivers of Plant Light Absorption

When I first started using light meters and learning about plant lighting, I kept seeing the terms chlorophyll a and chlorophyll b. At first, they felt like biology class leftovers I didn’t need to understand to grow plants. I quickly learned that dismissing them was a mistake. These two pigments are not just scientific terminology. […]

Why Is PAR Limited to 400–700 nm?

When I first started measuring light for my plants, I assumed that if a light meter covered broad wavelengths, it would automatically tell me everything I needed. I quickly ran into the term PAR (Photosynthetically Active Radiation) and found out that it’s defined specifically as the range from 400 to 700 nanometers. At first, this […]

With the Same Radiant Power, Does More Red Light Mean Higher PAR?

When I first started measuring plant light, I read a lot of technical posts about light spectra, radiant power, and how different wavelengths affect plants. One question that kept coming up was: If two light sources deliver the same radiant power, but one has more red light, will it register a higher PAR? At first, […]

How DLI Relates to Full Sun, Partial Shade, and Other Light Terms

When I first learned about plant light, terms like “full sun”, “partial shade”, and “DLI” felt like they came from two different worlds. I could read about them separately, but I struggled to connect the dots in my own garden. I had a spot labeled “full sun” that sometimes produced weak plants, and another labeled […]

What Does mol/m²/day Mean in Plant Lighting?

When I first started using a light meter in my garden, I was comfortable with instant measurements like PAR. I could measure light in the moment and get a number I understood. Then I learned about mol/m²/day. At first I thought it was just another complicated unit. It took several real gardening seasons and a […]

What Are the Units of PAR and Why Do They Matter?

When I first started measuring light for my plants, I quickly realized that the hardest part was not the measurement itself, but understanding the units. I kept seeing numbers written as µmol/m²/s, along with terms like PAR and PPFD. At first, they felt abstract and disconnected from what I was actually seeing in my garden. […]

Why Measuring DLI Under Sunlight Isn’t as Simple as It Seems

When I first started tracking light for my garden, I thought DLI (Daily Light Integral) would be simple: Take a PAR reading, multiply by hours of sun, and that’s your DLI. It took several weeks of sweat, unexpected plant responses, confusing data, and more than a few cloudy mornings before I finally realized… Measuring DLI […]

Why I Started Logging DLI Over Days, Weeks, and Seasons

When I first got my hands on a light meter, I thought I knew what I was doing: “Just take a few PAR readings now and then — that’s enough.” Boy, was I wrong. It took me months — seriously — of tracking light, watching plants, and adjusting my expectations before I truly understood: Light […]

Why You Should Track PAR Changes Throughout the Day

When I first got into measuring light for my plants, I had one simple idea: “Just measure PAR once in the morning — that should tell me everything.” Turns out… that was a big misunderstanding. Over the last couple of years, I’ve measured PAR dozens of times in my garden — at dawn, at midday, […]

Why “Full Sun” Beats µmol/m²/s in Everyday Gardening

When I first started gardening, I did what many curious growers do today —I tried to turn sunlight into numbers. I bought a PAR meter.I learned what µmol/m²/s meant.I started measuring light in my garden like a scientist. And yet, something strange kept happening. Plants labeled “full sun” kept growing better in places where the […]

Understanding PAR and DLI: What I Learned From Measuring Plant Light the Hard Way

When I first started measuring plant light, I believed something very simple: Higher PAR equals better growth. It didn’t take long for real plants — and real mistakes — to prove me wrong. Over the past few years, I’ve personally measured light conditions for dozens of plant setups, from indoor herbs and leafy greens to […]