Kale seedlings not growing well indoors - Ask Extension
Hello,
I planted several Starbor kale seedlings in trays in organic potting soil on 3/8. They've been in a greenhouse-type setup with grow lights (...
Knowledgebase
Kale seedlings not growing well indoors #927038
Asked March 30, 2026, 9:13 AM EDT
Hello,
I planted several Starbor kale seedlings in trays in organic potting soil on 3/8. They've been in a greenhouse-type setup with grow lights (photo). They germinated in three days but since then have struggled to grow. Some of them had roots coming out the bottom, so I transplanted them all to larger containers on 3/23. The greenhouse temp fluctuated between about 74 and 79 and I thought it might be too hot for the kale, so I took them out and put them on a table at ~70 room temp with just a lamp on them. Yesterday I started feeding them with 1-1-1 fertilizer. They've been well watered.
I've never planted kale from seed before and am wondering what could be going wrong. I was hoping to put them in the ground soon but they're much too small. Thanks for your advice!
Holly
Baltimore County Maryland
Expert Response
I should have said that the seedlings were planted in organic seed starter. Also, grow lights have been about 1-2 inches above the soil line.
Hello Holly,
Thank you so much for your question. Kale takes anywhere from 50to 80 days to mature, which would explain why it's still so small. Another factor is that it grows best between 60-75 F. I think that the temperature has been your limiting factor. Cool them down, and hopefully they'll grow better. Also, your LED light should be between 4" and 6" above the seedlings. You may need to supplement in the garden with purchased transplants in the meantime.
Please let us know if you have further questions!
Thank you so much for your question. Kale takes anywhere from 50to 80 days to mature, which would explain why it's still so small. Another factor is that it grows best between 60-75 F. I think that the temperature has been your limiting factor. Cool them down, and hopefully they'll grow better. Also, your LED light should be between 4" and 6" above the seedlings. You may need to supplement in the garden with purchased transplants in the meantime.
Please let us know if you have further questions!
