This is my first time trying to grow from seeds (or from anything for that matter) and my tomato seedlings sprouted up pretty rapidly over the past 2 days. Most of the guides I've seen have recommended leaving these clear covers on for quite some time after the seedling sprouts but these things are already becoming too tall for that it seems. They haven't actually touched the top of the container yet as far as I can tell because of how aggressively they are leaning towards the sun. I'm not sure if that is potentially harmful so I have been rotating the container a few times a day which causes them to lean back and forth over the course of the day which may be worse.

So I have a few questions:

  1. Should I remove the cover from this seed tray already?
  2. Should I be concerned with the amount of lean these seedlings are getting and if so what can I do to mitigate it?

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  • 1
    I always had trouble with cooking the seeds with a cover; even with indirect sunlight. I only use covers when rooting seedlings.
    – Evil Elf
    Mar 16, 2023 at 10:52

2 Answers 2


Indeed lean doesn't matter at this stage.

I presume the cover is there to prevent freezing if outdoors. So if stored indoors the cover doesn't matter, outdoors it can be removed when the night low is 5°C*.

Without the lid the humidity's gonna be reduced so water each day or two shallowly.

Do not replant them yet. Those "leaves" are actually cotyledon. Wait for 2 to 4 real leaves to appear and then replant.

* - the 5 figure is just pulled out of thin air. Do heed @Stepahnie 's comment and do Your independent research before proceeding

  • 3
    Temperature is crucial for tomato seedlings. The 5°C can lead to stunted growth which they potentially don’t recover from. The cover is also there to ensure high humidity which helps the very young seedlings thrive in the earliest stages. Not essential, if environment temperature is high enough and you are very diligent about watering.
    – Stephie
    Mar 25, 2023 at 8:09

The lean does not matter at this stage. Similarly, if they bend a little when they touch the lid, won't harm them either. The bends will auto-correct later with the upper part growing towards the light and the root being attracted to gravity/water.

I would keep it on for a few more days to see if any more sprout.

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