Under watering
 

We all hear to [B]not[/B] over water our seedlings, and we're familiar with the consequences. I'm wondering, though, what does under watering like?
How does it effect seedlings and how do you know if you're under watering?

I think it depends on what you mean by seedling and under watering. When they are and inch or two high or less, I strive for maintaining even moisture. As they get larger, I like to thoroughly water them, then let them dry out to just before they start to wilt before watering again. The timing of watering is a guess because that time shortens as the plant gets bigger and the fan blows on them more. Probably 2-3 times a Spring, they get to the point of starting to wilt before I water. With a good drink, they pop back up in no time. Personally, I think keeping them in cool temps, using a fan on them and letting them go from wet to dry are stressors that result in a thicker stalked, stronger plant. That is pure observation and not scientific at all, but, it works for me.

I have seen the effects of under watering this year, and in my very small plants it looked similar to sunburn or fertilizer burn. There is one side of my greenhouse that gets hotter than the other, and the plants on that far side stay warmer, and so dry out sooner. One plant died, a few were stunted because the leaves were damaged from going dry, but are recovering nicely.

I have had older, larger plants get too dry before, and the damage looked very much like foliage disease, lower leaves and branches withered and yellowed, some fruits and flowers aborted.

AR, I saw your other thread about seedlings being small and in my case I was having the same issues this year as you and I attribute it to under watering. I moved my seedlings/ lighting/ shelves etc into a closet this year to get them off the bar. Much better set up but the problem is I was having trouble seeing or reaching some of the seedlings in the back. I noticed when I went to pot up all the ones that seemed to be lagging behind in growth were nearly dried out. Since repotting I have kept up better with the watering and apply a diluted organic fertilizer and they seem to be recovering nicely. Hopefully no lasting effects.

It's actually kinda difficult to underwater seedlings in starter cells since the soil retains more moisture than is apparent.

So long as the surface dries out at least once a day, you're fine. When I'm starting, I check for surface dryness every morning and if a cell surface is well dried, I give the cell a shot from a syringe. (Easy to control and easy to reach the cell.)

The nasty effects of "too wet" don't happen when the surface is dry for a good part of the day. The nasty effects of "too dry" are crispy seedlings, so err on the side of too wet.

Now go use that Greyhound bus ticket.