The default herb schedule on the AeroGarden is 17 hours on, 7 hours off. That’s a lot of light. And for basil especially, it’s probably too much, not because basil can’t handle it, but because that kind of sustained photoperiod tends to push the plant toward flowering faster than you want. Getting your grow light schedule right for an indoor hydroponic garden is one of those things nobody explains clearly at setup, and the factory defaults don’t help. I’ve noticed my basil bolts noticeably quicker when I leave the factory setting alone. Dropping it to 14-15 hours made a real difference.
But before I get into the breakdown, the short version is below.
Quick Answer: Most countertop hydroponic systems default to 16-17 hours of light, which works for fruiting plants but accelerates bolting in herbs. For basil, cilantro, and other common herbs, 14-15 hours is enough. Lettuce is fine anywhere from 12-16 hours. Only tomatoes and fruiting crops actually need that 16-18 hour range. You can also run your lights at night without any harm to the plants, and potentially save on electricity if you’re on a time-of-use billing plan.
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What Your Machine’s Built-In Timer Actually Does
This is where most light schedule advice falls apart. Generic guides say “give plants 12-16 hours” and leave it there. But whether that advice is useful depends entirely on what timer your system already has built in.
The AeroGarden defaults to different settings depending on which grow profile you pick at setup. The herb and basil profile runs 17 hours on, 7 hours off. The flower and fruiting profile drops to 15.5 on, 8.5 off. You can override the start time by holding the light button on the unit. The light duration itself, though, is fixed to whatever profile you chose unless you use an external timer (more on that below).
The iDOO 12-pod has two preset modes: vegetable and fruit/flower. It adjusts the light cycle automatically based on which one you select. What it doesn’t give you is manual hour control without going into the app. The app has WiFi smart control, which is fine, but the on-device options are limited to those two modes.
Click & Grow is the most rigid of the bunch: 16 hours on, 8 off. Fixed. You cannot change it. That’s fine for most of what Click & Grow sells pods for, but it’s another reason I returned mine, there’s no flexibility built into the system at all. And honestly, for a brand that charges that much per pod, the least they could do is let you control your own light hours. It’s a small thing that adds up to a frustrating ownership experience.
How Many Hours Each Plant Type Actually Needs
Here’s the breakdown I use. Not gospel, but it’s what’s worked for me.
Herbs (basil, cilantro, dill, mint): 14-15 hours. The 17-hour AeroGarden default is fine for fast production, but if you want the plant to stay leafy longer and not bolt, pulling it back helps. My current basil has been going four-plus months on the same plant, I think keeping the photoperiod shorter has something to do with that.
Lettuce and leafy greens: 12-16 hours. Lettuce is pretty forgiving here. I run mine at 16 and haven’t had issues, but 12 works too, just slower growth. The tip burn problem is more about heat and airflow than light hours, so don’t cut hours trying to solve that specific issue.
Tomatoes, peppers, strawberries: 16-18 hours. Fruiting plants benefit from the longer exposure. My strawberry attempt in the iDOO is running at the full fruit/flower setting, which I think is somewhere around 16 hours. The flavor is still disappointing, but that’s a temperature problem, not a light hours problem.
Seedlings and germination: Less than you’d think. An iDOO Reddit user made a good point about keeping the light 2-3 inches from plant tops on its lowest setting during germination. More hours at high intensity right at the start can stress new seedlings. Let them establish first.
You’re going to ignore the seedling advice and wonder why you’re getting leggy sprouts.
I know because I did the same thing.
Does the Time of Day Matter?
No. Not for herbs, lettuce, or tomatoes.
Plants don’t care if their “day” starts at 6am or 10pm. What matters is that the schedule is consistent and that the dark period is actually dark. A Reddit user in r/Hydroponics put it plainly: any time is fine as long as it’s consistent. Another user mentioned running their basement setup to start at 7pm when off-peak billing kicks in. No impact on plants.
The one exception: if you’re running lights at night and your “dark period” falls during actual daylight hours, you need to block outside light from getting to the plants. Light bleed during the off phase is the only timing issue that actually matters for non-photoperiod plants like herbs and lettuce. Fruiting plants that need a true dark cycle are more sensitive to this.
The electricity math is real. The AeroGarden Harvest draws around 20W. At 16 hours a day, that’s roughly 320Wh daily, about $0.05 at the US average of $0.16/kWh. If you’re in California, Texas, or New York on time-of-use billing, off-peak rates run 30-40% cheaper. Over a year, per unit, that’s something like $5-7 saved. Not life-changing, but it’s there.
Light Intensity: What PPFD Actually Means
Lux and lumens measure how bright a light looks to a human eye. Plants don’t have human eyes. The number that matters is PPFD, which stands for Photosynthetic Photon Flux Density, and you can think of it as “how much usable light is actually hitting the plant per second.”
A r/Hydroponics user explained this better than most articles do: a 400 PPFD lamp positioned 12 inches from tomato plants needs about 16 hours to hit the right daily total. Move the light 4 inches further away and the PPFD drops, so you’d need 18 hours to compensate. The hours and the intensity are linked.
What this means practically: if your plants are stretching upward and getting leggy, your first instinct should be to lower the light or increase intensity before adding more hours. More hours at low PPFD doesn’t fix the same problem as more PPFD at the right hours.
The built-in lights on AeroGarden and iDOO systems are designed to be used at the heights their adjustable arms allow. Once plants grow into the light bar, you’ve lost the intensity you need. So more hours at that point don’t help anymore.
When to Add a Supplemental Light
The main use case for a supplemental strip light isn’t replacing your hydroponic garden’s built-in light. It’s when you’ve got a windowsill setup getting inconsistent natural light, or when you’re using your hydroponic system as a seed starter and need coverage for seedlings that have outgrown the height adjustment.
The Barrina T5 buy on Amazon strips are what I’d point someone toward for this. Full spectrum, linkable up to 8 units, and you can daisy-chain them over a shelf without a complicated mounting situation. I have them in mind for if I ever expand beyond my one dedicated kitchen shelf, my partner has a strict two-unit limit and a supplemental strip over a seed-starting tray might be how I sneak a third growing area past the rule. Check current price on Amazon.
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How to Override Your Built-In Light Schedule
If your system’s built-in timer doesn’t let you set custom hours, a mechanical outlet timer is the simplest fix. Plug your garden into the timer, set your own on/off schedule, done.
The BN-LINK mechanical timer see on Amazon is about $10 and has 96 on/off settings in a 24-hour period with 15-minute intervals. No app, no WiFi, no pairing issues. The one real downside: it resets if you lose power, so you’ll need to re-set the time after an outage. At $10, that’s a fair trade.
If you want something with more precision, the Grow1 digital timer check price on Amazon drops to 1-second intervals and handles 8 on/off settings per day over a 7-day period. More useful if you’re running a more complex lighting schedule or need very specific cycle lengths. It costs a bit more but the build feels solid.
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One note: when you plug your AeroGarden or iDOO into an external timer, the unit’s internal reminder lights (water, nutrients) still run on their own internal clock. The external timer only controls when power is delivered. You’re not breaking anything, just layering a second schedule on top.
This article is part of my Grow Lights for Indoor Hydroponics , a complete resource for countertop hydroponic growing.
Frequently Asked Questions
How long should grow lights be on for hydroponics?
It depends on what you’re growing. Herbs do well at 14-15 hours. Lettuce works fine from 12-16 hours. Fruiting plants like tomatoes and peppers need 16-18. More than 18 hours isn’t useful for most plants, they need a dark period to rest and move nutrients through the plant.
What is the best light schedule for indoor plants?
For non-photoperiod plants (herbs, lettuce, most greens), consistency matters more than the specific hours. Pick a schedule, stick to it, and make sure the dark period is actually dark. The time of day doesn’t matter, you can run lights overnight with no impact on plant health.
Is 12 hours of grow light too much?
Not too much, actually too little for most countertop hydroponic crops. Twelve hours is a reasonable minimum, but herbs and lettuce typically grow better at 14-16 hours. Twelve hours of light starts to make more sense during the dark period requirement for flowering plants, which most countertop gardens aren’t optimized for anyway.
What is the best lighting for indoor hydroponic gardens?
The built-in LED on your AeroGarden or iDOO is designed to work within the height range of the system and is generally adequate for herbs and greens. When you need supplemental coverage (windowsill setups, seed starting trays), full-spectrum T5 strip lights are a practical and affordable option. The measurement to pay attention to is PPFD, not lumens, lumens measure brightness for human eyes, not plant usability.
Should grow lights be left on all the time?
No. Plants need a dark period, this isn’t just about energy savings. Darkness is when plants rest and likely redistribute nutrients. Running lights 24/7 will stress most plants over time. Even if you don’t see immediate damage, you’ll get diminishing returns on the extra hours and probably faster bolting in herbs.
One thing worth keeping in mind: if your herbs are bolting faster than expected and you haven’t changed anything else, check your light hours before assuming it’s a nutrient or pH issue. That was one of the first things I got wrong, and it took me way too long to connect the dots. The nutrient and pH piece is its own rabbit hole, but light hours are an easier fix to try first.