Problems with leaves shriveling

16 years ago

Alright, so I had this exact problem with some of my seedlings last year, and here I go again. I wish I could figure out what I'm doing wrong!

I have started some licorice plant, some begonias, and some alteranthera on a heat mat, under lights. Everything germinated fine. Enter problem #1: my licorice plant and begonias were started Jan. 14. The begonias are just starting to get their second true leaf, and the licorice plant isn't much further ahead. I've started fertilizing, half strength, once a week. WHY are they growing so slowly? I know they are supposed to be slow starters, but, REALLY?! They'll never be ready for spring at this rate.

Problem # 2: For some reason, the alteranthera's leaves keep looking kind of shriveled/scorched on the ends, and then after a few days they dry up and fall off. The plant isn't dead, it keeps sending out new leaves, but the same thing happens. It is like it either a) isn't getting enough water or b)it is roasting. Should it not be on a heat mat? I'm trying raising the light some(maybe it is getting too much light?), but I don't know why that would be the problem...I was keeping it 4 in away, which should be OK. And I don't think I'm underwatering (or over watering, but I guess I could be wrong).

Anyway, it is so frustrating. I can't seem to start seeds properly! Last year I had the same problem, and nothing grew properly until I planted them out. My purple coneflower had the same leaves-crisping-off problem; the only difference is that last year I didn't use a heat mat. But those were perennials last year. I really need these annuals to be bedding-out plant size by late May! What am I doing wrong?

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Comments (4)

sleepy33
16 years ago
Heat mats are only for germinating the seeds BEFORE they sprout. After they've sprouted, they don't need bottom heat, and in fact grow better with an air/soil temp of around 55-65 degrees. Begonias are slow as all heck; what kind are yours? Tuberous begonia seedlings can go dormant/start to form tubers if they get too dry (as I have recently learned, unfortunately from personal experience).
weeper_11
Original Author
16 years ago
I had heard that they don't need bottom heat after germination, but I didn't think it would hurt these early starts, because they are all supposed to thrive with heat, and my basement isn't super warm. But maybe I'll try removing the mat for a couple of weeks and see what happens.

My begonias are fibrous; bada bing I think.
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digdirt2
16 years ago
The solution to both problems may be a simple as cutting back on your watering. Wet soil that isn't allowed to dry at all deprives the root of the oxygen they need even more than water. Wet soil not only slows and retards growth but causes fibrous root rot - the first sign of which is leaves looking shriveled and then dying while new growth develops.

Over-watering seedlings is by far the #1 problem for most growers - no one ever thinks they are doing it but they are ;) - and it is the #1 cause of seedling stress and death. It is also the reason many plants will improve once planted to the garden - they aren't getting over-watered any longer and the roots can finally breathe.

The only way to prove to yourself that you may have been over-watering is to cut it back - by half - and note how the plant growth improves.

but I didn't think it would hurt these early starts, because they are all supposed to thrive with heat

They thrive with AIR heat, not soil heat. Heat mats, once roots begin to develop, cook the roots. Leave the heat mats off the seedlings please.

TOO much light isn't possible so don't worry about that part and cooler air temps while they are seedlings is best as sleepy said above. It results in stockier, healthier seedlings IF you can eliminate the excessive watering problem.

Dave
weeper_11
Original Author
16 years ago
Alright, alright...I'll restrain my itchy watering hand. ;)

Thanks for the advice, guys. I'll remove the heat mat, and cut back on watering. Seriously, it'll be a nail-biting experience.