7 Things That Decide Whether Your Seed Tray Makes It in Florida

Everybody wants to talk about what to plant. Almost nobody talks about the part where the seed actually has to come up and stay alive.

I already gave you the list of what I am planting this month and what goes in a tray versus straight in the ground. This is the other half of it. This is the how.

And I need you to hear this part. Seed starting in Florida is not the same as seed starting anywhere else. Every video and every seed packet you are reading was written for somebody who is fighting cold. We are not fighting cold in September. We are fighting heat, humidity and an afternoon storm that shows up at four o'clock whether you were ready or not.

A tray that would sit happy on a windowsill in Ohio will cook on my porch in half a day. So here are the seven things that actually decide whether your tray makes it.

A few links below go to my Amazon storefront. If you buy through them I make a small commission and it costs you nothing extra. Everything on there is what we actually use.

1. The mix. This is the one people get wrong first.

Do not use soil out of your garden bed. Do not use the bag of potting soil sitting in your garage.

Garden soil packs down tight inside a little cell. Water hits it and it seals over. The roots on a brand new seedling are not strong enough to push through that, so the seed either never comes up or it comes up and then just sits there for three weeks looking stunted.

You want an actual seed starting mix. It is light, it is fluffy, it holds water without turning into mud. Black Gold is what I use and it is on my storefront under the seed starting list, along with the trays and dome lids.

Wet the mix in a bucket before you fill your cells. Get it damp like a wrung out sponge, then fill. If you fill the tray dry and water it after, the water runs straight down the sides and through the holes and the middle of the cell stays powder dry. You will not know until nothing comes up.

2. How deep, and why shallow is the safer mistake

General rule is you plant a seed about twice as deep as the seed is wide.

So a tomato seed, which is tiny, goes about a quarter inch down. A bean, which is big, goes an inch. Lettuce barely gets covered at all because it needs light to germinate, so press it onto the surface and dust it.

If you are not sure, go shallow. A seed planted a little too shallow will still come up. A seed buried too deep runs out of stored energy before it reaches the light and it dies down there, and you never find out why.

3. Water from the bottom, not the top

This is the change that fixed my trays more than anything else.

Set your cell tray inside a solid tray with no holes, and pour the water into the bottom one. The mix pulls it up through the drain holes. Give it fifteen or twenty minutes and pour off whatever it did not take.

Three things happen when you do it this way. The seeds do not get knocked out of place by a watering can. The surface stays drier, which matters a lot for the next thing on this list. And the roots grow down chasing the water instead of sitting shallow.

A tray in a Florida September will go from damp to bone dry in a single afternoon. Check it morning and evening. That is not me being dramatic, that is just what the sun does here this time of year.

4. Heat is not your problem here. Light is.

Everywhere else, people are buying heat mats to get seeds to germinate. In Florida in September you do not need one. Our soil is plenty warm. Tomatoes, peppers and eggplant will pop for you faster this month than they will any other time of year.

What gets people here is the second half. The seed comes up, and then it gets long and thin and floppy and falls over. That is not too much water. That is not enough light.

A windowsill is not enough light. It looks bright to your eye and it is nowhere near what that seedling needs. If your trays are inside, they need a light sitting a couple of inches above them for fourteen or so hours a day, and you raise it as they grow.

If your trays are outside, morning sun and afternoon shade. Full Florida afternoon sun on a tray of new seedlings will cook them and dry the cells out before you get home.

5. The lid comes off the second they sprout

Dome lids are for germination only. They hold humidity in while the seed is waking up, and that is genuinely useful for the first few days.

The minute you see green, the lid comes off. Leave it on and you are running a little swamp in September humidity, and that is exactly how you get damping off.

Damping off is a fungus, and it looks like this. Your seedlings come up looking perfect, and then one morning a few of them are lying flat with a pinched, dark, wet looking spot right where the stem meets the soil. They do not recover. And it spreads across the tray.

Prevention is all you have. Lid off early, air moving across the tray, water from the bottom so the surface can dry, and do not crowd your cells. I run a little fan on my trays and it has made a real difference in a wet season, and this one is going to be wet.

6. Thin them out. I know you do not want to.

Put two or three seeds in a cell because germination is never one hundred percent. Then when they come up, pick the strongest one and cut the others off at the soil line with scissors.

Cut them, do not pull them. Pulling tears up the roots of the one you are keeping.

Nobody wants to do this. It feels like throwing away a healthy plant. But two seedlings sharing one cell fight each other for water and light and you end up with two weak plants instead of one good one. Pick one and move on.

7. Harden them off before they go in the ground

Six weeks in a tray means October, and that is the goal. Tomatoes, peppers and eggplant started the first week of September go in the ground mid October, which is exactly when our nights finally drop enough for tomatoes to set fruit.

But you cannot take a seedling that has been sitting in filtered light and stick it straight into a Florida bed. It will scorch in two days.

Give it a week. An hour or two of morning sun the first day, a little more each day, and bring the tray back into shade in the afternoon. By the end of the week they can take a full day outside. Then plant them, and plant in the evening rather than the morning so they get the cool overnight hours to settle in instead of going straight into the sun.

Water them in well and keep them damp for the first week while the roots reach out.

What I am doing differently this year

We are heading into a very strong El Nino winter, which flips our dry season wet. I wrote about what that does to a Florida garden here.

For seed starting it changes three things for me. I am starting more than I need, because I lost my tomatoes and peppers this year and I would rather have extras than come up short. I am giving the trays more air than usual, because a damp winter is a fungus winter. And I am spacing everything wider when it goes in the ground than the tag tells me to.

My pumpkin bed is still occupied too, so some of these trays are going to sit a little longer than six weeks waiting on a spot. That is fine. A seedling potted up into a bigger container will wait on you. A seedling left crowded in a cell will not.

If you only fix one thing

Water from the bottom and get the dome lid off early. Between those two, that is most of the trays I have lost over the years.

I track all of this week by week over on Patreon, what went in, what came up, what died. Garden journal one week, a recipe the next, five dollars a month.

Tell me what you have got going in trays right now. And tell me if you are one of the people who cannot bring yourself to thin them, because I was that person for years.

Toni

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