Expert: Mike Mascio - 5/20/2008

Question
my sunflowers leaves are turning brown. It looks like they were getting burned, so I moved them into the shade. They are still in pots, because i grew them from seeds. What is wrong with them?
I was told too much wate and they have out grown their pot. Then I was told not enough sun. Can someone please help?

Answer
It could be any of the above. Sunflowers do not like wet feet, meaning saturated soil will cut off oxygen to the roots, depriving the plant of nutrients. The plant will literally suffocate.

Excess fertilizer will also burn the foliage of new plants. The general rule of thumb is that seedlings should only be fertilized once they produce their fourth set of leaves, and even then the fertilizer should be applied at 1/4 the recommended dilution rate for mature plants.

You should also be aware that sunflowers are extremely vulnerable to transplant shock. They do not like to be removed from their original location and tranplanted elsewhere. I learned this the hard way many years ago and lost 80% of the plants that I transplanted into the garden.

To avoid this scenario, it is best to direct sow sunflower seeds. If you want to get an early start, you can sow them in peat pots. Peat pots should be transplanted whole into the garden. They will then decompose, leaving the sunflower plants' roots undisturbed.

You didn't mention what size pot they are currently in. But if they are small, the root system may be compromised. At this point, you have no choice but to transplant the plants into the garden now and hope for the best. If you can salvage over half of the plants, that would be as good as can be expected.

Since seeds are relatively inexpensive, I would also sow seeds in the same bed as an insurance policy. Sunflowers grow quickly, so the direct sown seeds will still give you ample flowering throughout the growing season.

I hope this answered your question. Please write again if I can ever be of asssitance.

Regards,

Mike