Why are my tomato seedlings drooping and the leaves curling?
Question:
I am a first time gardener starting tomato seedlings inside. My seedlings are three weeks old as of Apr 20th. About a week ago they started drooping, leaves curling and some undersides of leaves have turned purple. I have spent a ton of time researching online and received every answer under the sun.
- Soil is moist but not wet
- Fertilized 3 days ago in hopes it would help with liquid 2 3 2 at half strength
- Soil meter read ph of 5.5 and temp of 22 deg celcius
- I have them under led lights during day and dark at night
- Just started running a fan for air movement today.
Answer:
Welcome to the world of gardening!
First let me point you to our UMaine Cooperative Extension Bulletin #2751, Starting Seeds at Home, and for later in the season the UNH Extension’s Fact Sheet on Growing Tomatoes and Fact Sheet on Pruning Tomatoes. The good news is that your seedlings look reasonably healthy in the photos.
I do notice a couple of things that may be contributing to the issues you mention. First and most importantly, while tomatoes do like things on the acidic side, a soil pH of 5.5 is toward the bottom end of their comfort zone–if you take a look at this nutrient availability chart from the Univ of MD Extension, you’ll see that 5.5 is getting problematic for absorption of the primary plant nutrients. They will tolerate it, but 6.2-6.5 is better. So you may be having some trouble with nutrient uptake by the seedlings, notably phosphorus (which can cause purpling of foliage). These are such small units of soil we’re dealing with, though, that I wouldn’t mess with trying to adjust the pH by adding anything. Hold off on any more fertilizer for now.
Next, I wonder if you have drainage holes in the bottom of the cups? It’s good to hear the soil is moist, but not wet, but containers without drainage holes are tricky to manage irrigation. You may have water accumulating near the bottom, which puts your seedlings at risk of damping off (a fungal condition that causes root rot)–this condition typically kills off smaller germinants outright, but larger plants like yours can start losing some foliage. If you do have any root rot issues, the medium needs to get dried a bit and pretty quickly.
If it were later in the season, I would recommend going ahead and hardening them off (an important step for first time gardeners) to transplant out because the outdoor air would help dry the soil a bit and getting them into their home for the season would help mitigate the pH, but you are a couple of weeks ahead of the standard timetable. We typically recommend starting tomatoes mid-April to be transplanted out June 1, and with the weather we’re having right now I sure wouldn’t put them outside now! But you will want to cheat a week or two ahead next month to plant them out, and mulch them well to help mitigate any late cool snaps up where you are.
Honestly, my advice for now is to transfer the seedlings to slightly larger pots with a little fresh soil-less medium (you can keep the existing medium that is around your root ball, but add in the new medium around it in the new pot–details about the right medium are in the seed starting bulletin above). It looks like you have a lot of seedlings, so that may sound daunting, but you’re going to need to nurse these along indoors for a few more weeks so they’ll appreciate the extra space, and it should help raise the pH and give you some extra drainage.
Let us know if you have any further questions as the season goes along. Happy gardening.