hardland
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Starting Tomato seedlings, direct sunlight any harm?

I am starting some more Tomato seedlings. I understand seedlings need moisture and warmth to sprout. Is it bad to have them in direct sunlight outside. Im starting mine in a screened patio in Sth FL. 85 degrees avg
Hey there Mister,
Can you tell me what happened to the seeds iv'e sown,
can you give me a reason sir, as to why they've never grown,

TZ -OH6
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Filtered light is better since full sun is over the saturation limit (more than is needed), and other problems such as heat, water loss, and wind often go along with full sun.

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applestar
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Wouldn't the screen provide a certain % of shade? It would definitely be filtered and not full-strength sunlight. I guess the question is is that enough?

TZ -OH6
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Hard to say if the screen porch would be enough. You would just have to see if the seedlings get leggy or not, and adjust accordingly.

Tomatoes like relative warmth to sprout (cool room temp up to 85), but develop better being cool for the first few weeks after sprouting (mid50s, 60s). Heating mats are most often used when the spring greenhouse/ grow room is to cold for fast sprouting. Peppers are the ones that really need warmer temps for god sprouting (80ish).


Much of the gardening lore about "warmth" comes from people in northern climates trying to get a jump on spring, and are comparing tomatoes to things like peas that go into the soil as soon as it thaws out.

hardland
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Location: Sth Florida

I have 3 batches of seedlings on the go. My seeds seem to sprout well, 4-5 days. It's after that point where they seem to grow very slowly. I have been viewing a blog where another gardener in my area has plants ready to go in the ground at 35-40 days and the plants are 8-10 inches with a good amount of true leaves. Mine seem very far behind this point, 4-5 inches and somewhat weak. I will take my camera home and take some pics to post tommorow. Here is my proceedure for seedlings: Thanks for any input you all may have:

I use seed starting mix or Fafard potting mix (very light mix)
I use peet pots, either 2 inch or 3.5 inch. 2 seeds in each pot.
I water daily in the morning.
When the seeds ahve sprouted I move them outside where they get 7+ hrs of full sun. Here in FL, the morning low is 70, the high about 85.
I leave the strongest stem and remove the weakest by snipping it off.
I replant when the plant is about 4 inches tall, recessing some of the stem in new soil.
I water every day, adding some fish emulsion every 3 days.

Maybe I am just being impatient. The plants have not stopped growing, just seem slow. Is it normal to wait 6-7 weeks from when you start the seed, to get to the point of final planting?
Hey there Mister,
Can you tell me what happened to the seeds iv'e sown,
can you give me a reason sir, as to why they've never grown,

TZ -OH6
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Posts: 2097
Joined: Fri Jul 25, 2008 7:27 pm
Location: Mid Ohio

Seems like stress from too much sun, too much water, and too much fertilizer. Peat pots cause problems with moisture control but probably help keep your full sun from cooking the rootballs as much as they wold with a plastic pot.


This is my method, which is fairly common.

Multiple seeds in small plastic cells full of damp potting mix (four or six packs from nursery seedlings). Sit cell pack in water to fully hydrate (~15 mins) set aside to sprout (4-5 days). When sprouting starts, sit under flourescent lights at room temperature, or in a large window away from the glass-heat.

When pots are light and mix seems dry (every 3-5 days depending on conditions) sit "pots" in water to rehydrate.

When the first true leaves expand and there is a bit of space between the leaves and the cotyledons I pull the roots apart to separate the plants and pot up in 3"-4" plastic pots or drink cups, burying the stem up to the cotyledons (this is probably at week 3). At this point, in the larger pots the plants need water less often until the plants grow larger and start to pull water from the soil. At the first watering after potting up (about 5 days later) I might use 1/4 strength fertilizer, but usually I wait a couple of weeks or don't fertilize at all until the last week or so before planting (week 5 or 6). At this time they may get extended periods of sunlight including midday sun), but before that only morning sun followed by bright shade (beginning shortly after potting up). Too much can go wrong with full sun on small seedlings, and I'm using April sun at higher latitudes with temps from 50-70. Your sun is brighter and temps are higher. If full sun can hit soil, not just leaves leaves, it can heat damp soil and cook the roots.

hardland
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Joined: Tue Apr 06, 2010 11:05 am
Location: Sth Florida

TZ, Thanks for your advice. I think your definately correct on the stress from heat/water/fert thing. I just put my thermostat out on the area I have the seedlings, even though our local temp here is supposed to be 86', I have a reading of 91' in the shade and 97 in full sun! I'm sure that is way to hot for seedlings that sprouted a week ago and I have had them out for 6-7 full hrs per day. The peat pots dry very quickly in that heat, hence the need for extra water. I have pulled everything back into the shaded patio, where it is still quite bright and cooler. I'm honestly thinking of setting up the grow lights and heating blanket I used last winter, it seemed to work better. I had no choice then, we had days of 50' highs and 39' lows. That was Jan, I was hoping to start earlier this year, I guess if I can get a few healthy plants in the ground by Mid Dec, early Jan, that will give me 90 days to harvest in early April. Florida sure has a wacky growing season!!
Hey there Mister,
Can you tell me what happened to the seeds iv'e sown,
can you give me a reason sir, as to why they've never grown,

TZ -OH6
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Posts: 2097
Joined: Fri Jul 25, 2008 7:27 pm
Location: Mid Ohio

Is there someplace like the north side of the house where the plants can get a few hours of earliest morning sun followed by indirect light? Open sky with directional shade from sun is a good light level. Its a shame to have to use lights when you don't have to.

hardland
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Posts: 248
Joined: Tue Apr 06, 2010 11:05 am
Location: Sth Florida

I'm looking for a new location. My therm is reading 91 in the shade by noon and it doesn't get below that before 4 on average, I'm wondering if that is just too hot.
Hey there Mister,
Can you tell me what happened to the seeds iv'e sown,
can you give me a reason sir, as to why they've never grown,

TZ -OH6
Super Green Thumb
Posts: 2097
Joined: Fri Jul 25, 2008 7:27 pm
Location: Mid Ohio

I used to grow various plants in a greenhouse that got up to 110 most days of the summer. It is not necessarily a lethal situation. As long as there is no problem with drying, a few hours in the upper 90s each day won't hurt as long as there is no direct sun to boost the temps of the pots into lethal range. If you have the peat pots touching each other and touching something on the sides (like some sort of plastic box) it will reduce evaporation. Airflow around the plants is the big drying factor. In the sun you would want the opposite, airflow around the potss for evaporative cooling of the rots.

It may be that a set of lights in an air conditioned house is the best way to go. It certainly is the proven way to go, but I think that you could still make it work outside if you had to.

hardland
Senior Member
Posts: 248
Joined: Tue Apr 06, 2010 11:05 am
Location: Sth Florida

I've moved the plants to a place where they get shade earlier. It's definately helped. They now get less sun, less water and less fish emulsion. The 30 day old plants are growing well and recovering from the earlier stress. I,m curious about one thing, if the plant gets to the point of planting, but later than it should have, will the earlier stress cause any problems later? I'v read posts where sometimes it causes BER or catfacing etc. I would rather put the healthiest plant possibe in the ground. I started some more seeds 2 weeks ago in both plastic and peat pots, the plastic ones are doing a lot better?
Hey there Mister,
Can you tell me what happened to the seeds iv'e sown,
can you give me a reason sir, as to why they've never grown,



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