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brown tips on leaves of lettuce in greenhouse
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Posted by joannaqcw NY 4/5 (My Page) on Thu, Nov 19, 09 at 9:49
I'm trying lettuce in the greenhouse this year. The plants were sown in the third week of August and are growing in pots 6-8" deep and 6-10" wide (one plant per pot). The soil mix is 1 part sand, 2 parts compost.
The plants grew and thrived and we've had several cuttings, but now they are starting to brown at the tips.
Is this a fertilizer deficiency? (I haven't spray fertilized them; the kale, which is also nutrient-hungry, seems to do well through the winter in the rich soil mix without additional supplements.) Or a sign of too much water, or not enough? Or a lack of light? Any advice would be greatly appreciated. Thank you.
Joanna |
Follow-Up Postings:
RE: brown tips on leaves of lettuce in greenhouse
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| Your plants are probably seeing several days of low light proceeded by a bright sunny day or two. The plant jumps and grows too fast. Sounds like too much compost as well. Depending on the potency of your compost, you should use somewhere in the 10 to 20 percent range to start plants, the rest peat, perlite, sand, or whatever else you want. As the plant grows use some visual cues to dertermine when the plant growth starts slowing down, and leaves start changing from a strong green to a duller green. This would be the time to add more compost as a top dress. Burnt tips is a sign of too much fertilizer in many cases. Overwatering might contribute as well. Start conservatively as the plants get going, and add fertility as they mature. Suplimental lighting to even out low light days might help even out the grow as well, but you need a 400 watt High pressure sodium bulb to really amount to anything. Just keep experimenting with your mix, and I think you should be able to improve your results. It might be difficult to eliminate this problems completely with this growing technique |
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