Grow light vs growing in window

I started some tomato seeds in early April. After a few weeks (around 4/17), I moved some of them under a grow light. The grow light is in an aluminum foil lined box in the basement and I used a timer to give it 16-18 hours of light each day (16 initially, then 18 after a week or two).

Now, after a month, there is a quite a bit of difference, as you can see from the below pic. Both are Sun Gold’s which I planted at the same time. After comparing today,I moved all my tomato seedlings to the box.


Yes I do mine under lights. I have a fan too to further harden the stem. I have T5 4 bulb 4 foot lights. It works amazingly well. I have been trying to plant them out but have not had much time. I have about half planted out now.


Wow, great visual. I’ve been wanting to get a grow light, but also NOT wanting to spend the money - all mine are window seedlings, and they look like your little plant on the right. Maybe next year I’ll set up lights for the poor things!

Maybe you need to clean your window :wink: My tomato plants are much farther along because I started them late Feb. I start them using window light during the day and move them under light after in a closet next to the southern window. I stop using lights in April when plants get too big for setup. They keep growing just as fast with window light at that point and no plant I grow ever resembles the one you have using window light. It looks malnourished of more than light.

I just moved 4 of my largest plants outdoors next to a southern wall to harden them off. I still have a few against my southern window but most are in my fake green house (no heat beyond the warming mats which I also use through March in my house).

Maybe you keep your room cool and the medium isn’t warm enough for tomato roots.

I start plants so early so I can begin harvesting some fruit in late June. This year I plan to also do a late planting of a couple favorite varieties like Brandy Boy, so early blight doesn’t limit my Sept-hopefully Oct harvest to Country Taste, Sun Gold and Sun Chocolate, which resist the disease pretty well. I prefer brandywine types for flavor.

I grow them all organically once they are in soil. In the past I’ve used fertilizers like Miracle Grow to get them off to a fast start. This year I’m even less purist and using Osmecote, which works at least as well and requires less effort. The only thing is the 90 day release makes my fertilization a certain amount synthetic even after planting in soil, which bothers the hippy side of my brain. The hippy side has lost most of its dominance since I first tried growing fruit organically in the east about 30 years ago.

But once in the garden I eschew synthetic interventions for veg production although army worms try my patience these days as do white-fly and aphids on kale.

Putting tomato plants into soil not warm enough to allow proper root function only encourages early blight and does not lead to earlier harvest for me. With the help of some black landscape fabric, soil by driveway should be warm enough some time next week. My two Sungold plants already have small tomatoes on them and may have ripe fruit by about June 20th. Just not enough then to replace store-bought- that will take about 2 more weeks, I reckon.

They will get weekly apps of copper soap until first tomatoes are getting fairly close to ripe. When I first moved here there was no blight and I could throw plastic over a plant before first frost and harvest until about mid-Nov. Then take the unripe tomatoes and connecting vines indoors and eat pretty good tomatoes until Christmas. I’m hoping I can duplicate that by putting out a second planting in mid-June that ripen first tomatoes in Sept.


Window light is almost never as bright as you think it is, and rarely produces as much PAR as a good grow light.

Yes, a south window can be essentially full sun. However, you don’t get the “sky brightness” you do outdoors. Instead, you have virtual darkness (by photosynthetic standards) in the non-window direction.

Plus, few homes actually have a window that is oriented correctly, large enough, and not obstructed by anything. Unless you have a sunroom or Florida room.

My house faces west. It was built in the late 70s with the “energy efficient” practice of only placing windows on the front and back of the house, with no windows on the sides. The west windows are obstructed by trees. One East window is OK-ish but not great. I get growth like your second photo.

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I know you don’t mind spending money on a good product. You may want to buy this.

My husband buy this “closet”. It came with a structure to hold the closet in shape. The inside is line with reflective material. The outside is black woven fabric.

Any plants that need to be in a dark place, you just close the two panel door of the closet by zipping it up. It really looks like a portable wardrobe closet. This closet and the lights work great together.


A very nice set up Tippy!


Very nice! Where did he buy it from? Thanks

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It is a grow tent. The one we bought is a brand called Galaxy. We bought it from

The gold standard of grow tents is a brand called Gorilla Tent. It is expensive.

If you want to use it for seedling, you can get a used grow tent from Craigslist or Facebook Marketplace, a lot cheaper.


The window itself is pretty clean, but there are other plants which could take some of the light. After moving all the tomatoes into the grow box, here is what the desk in front of the window looked like.

The tall, thin plants near the window are jujube seedlings and you can probably tell the foreground plants are young figs. The window is actually SSE, so I had the tomatoes in it until early afternoon, then was moving them to a West facing window (and back again each night in preparation for the next morning).

The grow lights are a lot less work. In fact, that was somewhat of a problem, as I tried growing jujube and figs in it over the winter and I kept forgetting to water them, as they were out of sight and out of mind. But for the tomatoes, I managed to keep on it every 2-4 days for the month they have been down there.

That is possible- I think I reused the potting soil from something which died (maybe a failed fig or two) and divided it up into smaller pots. I probably don’t fertilize enough. I did add some Miracle Grow granules to the ground when planting outside.

The forecast for today was all day clouds, so I figured there would be a gradual acclimation and planted the biggest one yesterday. Now, it has been sunny for a good chunk of the day, so it may have some issues.

I don’t think it is too cool. It is my home office, and I like to stay nice and warm. The main area of the house is about 70 (bedrooms are cooler) during the winter/spring and my office is 75-80, as it is heated by computer hardware, S and W windows, and by being the first room to get the hot air from the heating system.

I’m growing 3 of those 4. The Brandy Boy and Sun Gold seeds germinated very well, and I ended up having to pull some extras (which I tried transplanting, but am not sure it will work). I think that only 1 of 10-12 Country Taste seeds germinated.

I wasn’t even planning to grow any from seed- just to plant the ones my parents bring by from a nursery, as I usually do. But, with Corona, I wasn’t sure what would happen, so I started them (a bit late) in the first week of April and a second set (the Brandy Boy, Mexico, and King of Siberia) in mid-April. Turns out that they did come by and drop off some plants and pick up a bunch of things I dug up in the yard (gooseberries, currants, and for some reason Rose of Sharon), apple scionwood, and some extra seed potatoes. So, now I’ll be re-arranging things and probably growing more tomatoes than I planned. My wife should like that, as the tomatoes are for her.

I did plant a couple tomatoes from a grocery store on 4/26. I thought that was late enough, but our unusually cold spring weather struck and we got down right around 32F and they got somewhat zapped. They weren’t killed, but they don’t look very healthy. I’ll give them a bit of time to see if they recover, but if not, I’ll re-purpose the space.

I’ll be interested to hear if the later planting lasts longer, or if it gets the maladys from the already mature plants. Each year, I have some plants which get unhealthy quickly and others seem to do pretty well. Big Beef has consistently been #1 and I have several of it again this year. I didn’t always keep great records, but looking back at notes, Mt Fresh, Sun Gold, and King of Siberia seemed pretty good as well, so they are back too.

Nice- that setup looks very professional.

I don’t mind, but grow closet might be noticeable enough around the house that my wife would take an interest :slight_smile:
I checked Craigslist and didn’t see any locally, but there were a few in NYC. Not cheap either. I bet you could make one, by taking one of the metal shelves and connecting lights to the top tier. Then build a frame around it and line it with extra sheet metal, to reflect light back. I’ll keep it in mind, but may also look to see if any deals appear on Craigslist. Most things would look better than my current setup with a plastic bin lined with aluminum foil and lights suspected by bungee cables and covered with a tarp.


I think it also depends on if you have double paned windows and insect mesh.

I can see the insect mesh blocking a good 10-15% of the light.

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made mine out of 2’’ x 2’‘s and a large silver tarp stapled around it. its 6’ x 8’ x 7’ tall. the door is a small tarp folded in half. stapled the ends together and screwed to the top. screwed a piece of 2’’ x 2’’ at the bottom. just need to push it aside to go in . put in a inline fan near the top to draw air out of the tent to control humidity and heat. also have a small desk fan ocillating over the tops of the plants. total cost was $40 to build and a couple hrs.of time.

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@BobVance and @moose71,
My husband did say that people who are handy can build one themselves.

The size of ours is 2×4. We bought it a year ago for $100 (after a coupon discount).


I’ve tried it before and had bad performance from late plants, but 2 years ago I had a volunteer grow in my garden from seed in my compost. It was apparently a seed from one of the Brandywine hybrids I grow, maybe Brandy Boy- anyway, it came up much later than when my other plants started and bore its fruit late, giving my my most delicious late tomatoes that year.

I thought it was just that the strain was resistant, and it was in a part of my garden with no nearby tomatoes so I saved its seed and planted them last year, but it wasn’t quite as good as Brandy Boy and simply had crop sooner because it started sooner and burned out like all of my other gourmet beefy tomatoes.

Whence, I will try late planting with my own and a legitimate Brandy Boy plant or two and see what they do.


Maybe that was the key. If it was near other tomatoes, they could spread the fungal issues to it.

I can be considered handy, as long as it is acceptable for the result to look like it was put together by the kid who did the project without any help from their parents :slight_smile:


I move my tomatoes all over but haven’t gotten much help by having individual plants far from others. The main issue here seems to be eastern exposure. The sooner in the day the sun hits the plants the longer lived they are. Tomatoes have taught me that about fungus over the years and it’s just as true of fruit trees- that is the benefit in our humid climate of eastern exposure and early evaporation of dew.

The tomato grew in the worst part of my veg garden for eastern exposure. I didn’t really think about that until you brought it up.

I’m still thinking it has something to do with being a potato leaf, indeterminate variety and starting late, but we will see this season. Having no stonefruit makes me more focused on my vegetables and fruiting annuals.

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Maybe you need Eastern exposure to get a good long season out of a tomato and putting it close to other new plants doesn’t help/hurt. But putting the new ones near old diseased ones could have a bigger, more immediate negative impact, Just a thought.

I suppose the other option is to put a little clear tent over a few tomatoes to keep them going indefinitely :slight_smile:

You have no stonefruit at all this year?? I’ve gotten pretty behind on a lot of posts and need to catch up. To get none at all, I think it would have had to be 5 degrees colder than I got recently (enough to hurt, but not kill a tomato). I just sprayed mine yesterday, as I was starting to see PC bites. Some of the trees seemed a bit thin on set, but most had at least some. And the Heath Cling peach at a rental (shockingly, planted by the previous owner) further South than my house by ~10 minutes, was loaded (I’ll need to go thin…).

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30 years ago I knew little about growing fruit in conditions outside of S. CA. Otherwise I may have held out for a better spot to have an orchard. Sometimes just a couple degrees makes all the difference.

Here is my set up and it beats a southern window by many lumens. If I were to buy today I would go LED. My lights are over 10 years old. Been doing this forever. I still have extra bulbs too. I will go LED one day.

I have 2 4 foot, 4 bulb T5 Fluorescent HO and a 2nd that is VHO. I have old shop lights I use for side lights. I never added reflective material, but I should.

I bought shelving from Sam’s. Kinda mini commercial shelves. I like the ones with mesh metal shelving. I use Ratchet Rope to hold the lights up

I also use wooden shelves lined with a thick shelving material

The lights are designed for plants and have highly reflective material around the bulbs.

I’m almost done using them for the year. I want to start some flower seed this week and I will be done. Storing my supplies on the lower shelf now. Notice the fan on the right? Bunge corded cheap fan.

On another subject
Fruit set mine was terrible last year. This year everything looks fantastic.


even $200 leds are much better that T5s plus you would cut your electric bill significantly. just be careful to follow the leds instructions. you put a led 12in from seedlings and they’re fried! 3ft. is best.