June 6, 2009

1 - Transplants can be shocked by the transplant process.

Yard and Garden June 6, 2009


I planted mammoth Russian sunflower seeds in April. They germinated quickly on my upstairs deck with its strong east sunlight. When they were about 8 inches high I transplanted them into my yard which is walled in but gets good sunlight from noon until sunset. They are in a north facing site. Now they do not look good. They are leggy and have lost all leaves from about 9 -10 inches down. What am I doing wrong? Can I move them in pots back to my deck at some point?

- Loni G.


Based on the information you have written, I suspect you are observing several problems associated with transplanting.

When you moved the plants to your yard, they went from a protected location with morning sun to a more exposed location that has brighter sunlight and more heat. They are also probably more exposed to the wind. The loss of the lower leaves is probably disposal of shade leaves that were formed in the more protected location as the plant develops sun leaves that are better adapted to the new location.

You may also be seeing transplant shock as the plants are trying to develop roots in the landscape soil which is probably significantly different from the potting soil in which you started the seedlings. Potting soil is more acidic than most New Mexico soils and contains less mineral salt that can stress the plants, especially if they are drying more quickly in the exposed location in your garden. Addition of significant quantities of organic matter (well-decomposed compost) to the garden before transplanting helps avoid this. If you fertilized, you may have over fertilized. If you did not add fertilizer, nutrients may be needed. You should irrigate the plants frequently in the first few weeks after transplanting to prevent drying as the transplants develop more extensive root systems in the garden. Then as the roots develop, you can water less frequently, but more deeply. Organic mulch (several layers of newspaper, straw, bark, wood chips, or other mulch material) may also help conserve water and speed development of a good root system.

You should see your plants continuing to develop if you fertilize lightly and irrigate appropriately. They will develop new, larger leaves, and continue to grow. Repotting and moving them back to the deck will probably not be necessary and may do more harm than good. Next year you may want to plant the seed directly into well-prepared garden soil and avoid transplanting and transplant shock.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


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