Issue: May 13th

Blossom end rot in container grown tomatoes

I'm growing several tomato varieties in containers and am having trouble with blossom end rot. I water every morning and by evening they are completely dry. I also fertilize every 2 weeks. I have bark mulch. What am I doing wrong? Darla, Las Cruces

The problem is probably that the containers are too small. This is evidenced by the fact that by evening they are completely dry. You didn't indicate anything about the potting soil that you are using. The potting soil could be a minor source of the problem if it is deficient in calcium. However, your water should supply sufficient calcium unless you are watering with distilled water.

Blossom end rot is caused by a deficiency of calcium at the blossom end of the small fruit as it begins to form. The calcium is part of the "glue" that glues cells together. A deficiency of calcium will appear as blossom end rot when the affected area begin to breakdown as the fruit enlarges. Once the blossom end rot appears, there is no solution for that fruit.

In New Mexico, calcium deficiency in the soil is not a problem, except perhaps in potting soil, but that is usually remedied by the calcium in our water. Here in our dry state, the problem occurs when the calcium fails to reach the end of small developing fruit because of drought stress.

The calcium travels through the plant dissolved in water. On days when the plants wilt, there is often insufficient water to carry the necessary calcium to the end of the new fruit. Then, though damage has been done, the symptoms do not appear for a few weeks until it appears in the enlarging fruit. The solution is to prevent the wilting of the plants.

In your case, moving the tomatoes to a larger container with a greater volume of soil, and thus a greater reservoir of water, may help. Another solution is to water the plants during the middle of the day. Finally, and probably a good idea in combination with either of the previous answers, is to place the containers and the plants in a place that is sunny in the mornings but shady in the afternoons.

Another good idea is to use light-colored pots for containers, or place something between the sun and the pot so that the pot is shaded. This will reduce the heating of the soil in the pot, reducing evaporation and damage to tender roots in the soil.

Is it ok to transplant bulbs now?

The leaves on my daffodils and tulips have turned yellow and are dying back. Can I transplant them now?

Yes, now that the leaves are dying back, they have completed their work and it is safe to dig them. However, it is best, especially for the tulips, to store the bulbs for the summer and replant them in the fall. This will give you plenty of time to prepare the planting bed, adding organic matter and phosphate fertilizer to the soil. During the storage period, keep the bulbs relatively dry so they do not rot. Store them is a cool place. The garage in New Mexico is not usually a good place to store them.

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.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!