skip to main content

Growing Tomatoes

T-5 Grow light question on seedlings that just germinated

9 years ago

I should no this by now, but seedlings with out true leaves can you put them on 24 hours a day? or should I give them a 4-6 hour break until they get true leaves? I am using T-5 lights about 5 inches above with Jiffy peat pellets. The seedlings are around 10 days old that just sprouted 5-7 days ago.

Thanks All

Sort by:Oldest

Comments (13)

Seysonn_ 8a-NC/HZ-7
9 years ago
General consensus is to keep the lights 14- 16 hours on and 8 -10 hours off.
That is how I have been doing and the results are good.
Plants (most of them) need a rest/ sleep/darkness time to recuperate also.

Seysonn
Ohiofem 6a/5b Southwest Ohio
9 years ago
When I used standard T12 shop lights to grow my seedlings, I left them on 24/7 from the beginning, and they seemed to grow faster and stockier that way. When I started using T5 lights a couple years ago, they seemed to do better with a six hour dark period each night.
Related Discussions
Leggy seedlings...start over or just germinate outdoors?
Q
Comments (13)
>NilaJones, thanks for your input for our specific area. Do you really think it's ok to put seedlings outside this early? Last year, I sowed seeds direct into the ground outdoors around Mid-May, and the poor things had to suffer through 2 hail storms and some cold spells. Portland has some weird weather. You're very welcome :). Outside, yes. And it's especially important if you don't have adequate artificial light for them indoors. In the ground is different story. If we get a cold snap, you can bring seedling trays of tropical plants like eggplant and tomatoes indoors for a night. Other babies like kale, lettuce, peas, etc. are happiest with cool weather anyway, so you can go ahead and plant them in the ground if the snails won't eat them.. They can stay out even when it's below freezing, this time of year. And all winter, most years. Hail is not a problem unless your seedlings are so tiny that a hailstone hits one and kills it. When we get hail, air and ground temperatures are still pretty warm. You notice the hail melts in 5 minutes :). I planted out my pole beans a week ago. I worried about them a little last night, with the wind and heavy rain, but they looked so happy this morning! They like this kind of weather :). Their root systems are not big enough for hot sun yet. Cool and moist is just what they want.
...See More
Watering the Just Germinated Seedlings
Q
Comments (5)
Thanks Al Talking of true leaves, generally how long does it take to get to the first set of true leaves. Indoors with the ideal circumstances, when will the first true leaves appear? I feel mine are not doing as they should. Infact they have stopped at the seed leaves for quite a number of days now. Some of the seedlings even stopped emerging above the soil lines i.e. part of their leaves are still under the soil :( I bought a room thermometer today and measured the temps around the seedling near the fluorescent lights and it was around 91-92. I placed a fan and set it on a lowest speed and the temp came down to 81-82F. I am still not sure when to water them. It does feel a bit moist under the surface of the soil - but then I dont know how moist it should be. Watering is becoming a real problem for me. I really can figure out when to water. Last 2-3 days, I bottom watered and it went fine. But due to peat based soil - it holds a lot of water - therefore I put it on a pile of sand and it wicked the water out - I could see the sand getting quite wet. To relive myself from the pressure of over or underwatering - can I do this every other day - bottom watering and using sand to wick out the extra water. Will this practice make me free of thinking that I have over watered? With 81-92F. 12 hours of florescent lights, 2-3 hours of morning sun and watering method as prescribed above. Are these some ideal circumstances that I am providing to my little seedlings?
...See More
seed starting soil, T5 lights Q and when to seperate seedlings?
Q
Comments (2)
As I posted on your other post about this "The only "black sticky crud" I can think of was once a layer of green algae that has died. If that's it it should just lift off in pieces. " T5 put out more light and more heat so they are used somewhat higher above the plants than are T12 and T8. The supposed ideal is 6-8" but that assume ideal conditions - which don't exist in real life so you have to experiment in your growing environment. Personally I find 4" to be good for most things but 3" is better IF you have adequate air circulation around the plants with fans. Too close isn't going to hurt the plants except they dry out more quickly. Too far makes them leggy which you can't really fix so too close is better than too high. No seedlings are "skinny in the beginning". That is caused by lack of light and too hot growing ambience. So your lights are too high or your air temps are too hot or both. 3> Your choice. Some clip, most separate. Easy to do and can be done at any time from the cotyledon stage to first set of true leaves. Only difference is ease of handling. I've read here (FAQs) and other places to fertilize seedlings soon after they sprout. Not sure where you found that in the FAQs. The one on fertilizing talks about fertilizing "after transplanting" only, not after they sprout. Big difference! The standard recommendation is well-diluted feedings every 7-10 days AFTER the plants develop their second set of true leaves. I do want to be organic. I don't like the idea of fertilizers. My tomatoes and eggplants are heirloom. Peppers are new mexico varieties. I don't know if this makes a difference. All plants need the nutrients supplied by fertilizers in some form. Heirloom or hybrid or variety makes no difference. They can't grow without them. So if you want to be organic just use one of the many organic fertilizers available. There are 100's of them. Dave
...See More
Germinating with Inadequate Grow Lights
Q
Comments (6)
Maybe I'm confusing nominal wattage with actual wattage. What wattage would I actually be looking for in a 2' fixture over one flat? I have very little space in my room (it's about 80 sq. ft, with a bed and a desk taking up much of that), but I do have plenty of space out on the south-facing lawn of the building. I can leave massive pots out there and groundskeeping is happy to just leave it alone. And if there's ever any trouble, one of the other dorms has a garden plot that goes mostly unused. It's a little far away, but if I had to, I could replant into the ground there.
...See More
thebutcher
Original Author
9 years ago
Thanks both of you, early this morning around 3 am I turned it off for about 6 hours and will continue the process and go up to 8 and see how it works out. Now off to the garden center to get some more supplies and probably pick up some more seeds and some more mix for a backup plan just in case. My T-5 JumpStart 2ft lamp is now on its 3rd year so was just worried if it was losing its ability.
ncrealestateguy
9 years ago
When I first started growing my tomatos from seed, the first three years I left my T5s on 24 hours / day. It really stressed the plants out to the point of where it made the leaves appear to variegate. I asked around, and reduced the lights to 12on and 12 off. They have done great ever since.
Seysonn_ 8a-NC/HZ-7
9 years ago
What we can do is to copy optimum natural environment.
In early to mid spring, when things like peppers and tomatoes germinate naturally, day light length is 13 to 14 hours in a lot of places . So then 13 to 14 hours sounds like optimum to me. We take it a bit too far, maybe, and give them 16 hours of light. So logically (to me) 14 hours is better than 12 or 16 hours. How much difference all this make? We don't know unless one does a lab type test and measure the differences.

Seysonn
Ohiofem 6a/5b Southwest Ohio
9 years ago
It is not just the quantity of light (number of hours) but also the quality of light that matters. A T12 light gives much weaker light than a T5. Neither gives a plant the equivalent light energy or spectrum of the sun. I definitely saw an improvement in growth when I increased the number of hours my seedlings were exposed to T12 lights, and 24/7 produced the best results. With a better light source, like T5s, a dark period seemed to help. But I think 18 hours of T5 light was better than 14 or 16. HID and HPS lights provide much better light than any fluorescent light can, and could probably be used for a shorter light cycle. Choosing supplemental lighting that provides something close to what natural sunlight provides is more complicated than just matching the number of hours of exposure.
Seysonn_ 8a-NC/HZ-7
9 years ago
Yes, Ohiofem,
What you describe as "quality" in a way is also "quantity" in terms of lumen. It is also known that tomato plants don't need 12 hours ( or more) of intense sun for their photosynthesis needs.
I can tell by looking at my seedlings if they are getting enough light or not. Are they spindly, stocky ? There are watering , fertilizing and temperature factors here too. So you have to kinda play by the ear. .

Another issue here, other than the duration, Is the light spectrum choice.
For seedlings, we don't want to encourage them to flower or fruit, but to develop good roots system. For this purpose , I think that cool spectrum is the best. But if you wanted to grow under light permanently, then you would choose different spectrum range

Seysonn
edweather USDA 9a, HZ 9, Sunset 28
9 years ago
Hey all, My seedlings are up about a week too, and I am using an elcheapo 4 foot 2 bulb shop light over them. Not exactly sure what bulbs are in it, probably 40W, and 16hrs on and 8 off seems to work for me. One of those timer thingys really helps too.
Seysonn_ 8a-NC/HZ-7
9 years ago
Hi Ed.
The T8 bulbs are 32w. I think T12s are 40 something watt. For seedlings it is not too important what type of bulbs are they. Daylight type 6500k is better.
So, when is your expected plant out date is. I know it is TOOOO cold up there now but by your plant out date things should be back to normal.

Seysonn
edweather USDA 9a, HZ 9, Sunset 28
9 years ago
Come heck or high water my plant-out date will be May 1 with protection. Seems like a million years away now. Today I went out to try and chop away some of the snow pack that has captured some of my lower blueberry limbs, and I just gave up. It was like trying to chop away tundra :-(
Seysonn_ 8a-NC/HZ-7
9 years ago
Ed, a few warm days and all that snow and ice can melt away. This has been just a tough winter back East. Keep focused and take care of those germinates.

Seysonn
edweather USDA 9a, HZ 9, Sunset 28
9 years ago
Sounds good. BTW my bulbs are 34W fwiw.
Seysonn_ 8a-NC/HZ-7
9 years ago
last modified: 9 years ago
Ed, so T8 bulbs are 34w . I was off by 2w..
I am running 3 units now { 34 x 2 x 3 =204w , x 16 hrs = 3.26 kwhr per day). Cost is less than a cup of coffee at StarBuck's .

Seysonn

Related Stories

GARDENING GUIDES Seeds or Seedlings? How to Get Your Garden Started

By Abundant City

Growing delicious herbs and vegetables starts with knowing your goals and when you want to plant

EDIBLE GARDENS Summer Crops: How to Grow Tomatoes

By Marianne Lipanovich

Plant tomato seedlings in spring for one of the best tastes of summer, fresh from your backyard

FARM YOUR YARD 10 Easy Edibles to Grow in Containers

By Marianne Lipanovich

These herbs, vegetables and fruits are just as happy in a pot as they are in the ground

GARDENING GUIDES No-Regret Plants: 5 Questions Smart Shoppers Ask

By Jocelyn H. Chilvers

Quit wasting money and time at the garden center. This checklist will ensure that the plants you're eyeing will stick around in your yard

FALL GARDENING 5 Fall Fruits You Can Grow in Containers

Brighten your porch or patio with a potted pomegranate, kumquat, blueberry bush or another great fall fruit

COOL-SEASON CROPS Cool-Season Vegetables: How to Grow Peas

By Marianne Lipanovich

Their sweetness isn't just for spring. Peas thrive in cool weather too, adding a garden-fresh note to soups, salads and more through fall

FARM YOUR YARD How to Grow Vegetables in Containers

By Annie Thornton

Get glorious vegetables and fruits on your patio with a pro’s guidance — including his personal recipe for potting mix

CONTAINER GARDENS 8 Easy Container Plants to Grow From Seed

Get beautiful blooms and herbs in summer by starting these choice garden picks from seed in spring

EDIBLE GARDENS How to Grow Your Own Sweet Summer Crops

By Marianne Lipanovich

This guide will help any gardener get started on growing the freshest warm-season veggies and berries for summer

SUMMER FRUITS AND VEGETABLES How to Grow Your Own Fresh, Sweet Corn

By Marianne Lipanovich

Here's how to plant and care for your own mini cornfield

Sponsored

Structural Remodeling

Franklin County's Heavy Timber Specialists | Best of Houzz 2020!

More Discussions

Has anyone heard of a storage tomato? Looking at Giallorosso di Crispi

4

"Purple" tomatoes?

4

What tools and materials for planting tomato

0