Hollow Stem

You need to know about hollow stem if you grow members of the cabbage family or cucumbers.

Hollow stem is a physiological condition that damages the main supporting stem that holds up your cabbage, broccoli, or cauliflower. At first, small cracks develop in the center of the main stem. As the stem grows, the cracks enlarge, creating cavities prone to pest infestations and diseases, especially rotting.

The damage is conspicuous when you cut open the stem of a plant with hollow stem.

Cucumber with hollow stem (David B. Langston, University of Georgia, Bugwood.org) CC BY-SA 3.0

Causes of hollow stem

Too much nitrogen and hot temperatures are bad news for cole crops. The nitrogen causes rapid growth, but the heat puts too much strain on these cool-weather crops. As cracks develop within the stem, the pith is lost, and the stem weakens.

Hollow stem and boron

For many years, botanists and gardeners blamed boron deficiencies for hollow stem. We now know that this is not true. Boron deficiencies darken the edges of areas damaged by hollow stem, but the boron deficiency does not cause the disorder. If you suspect your soil is deficient in boron, send a sample to a lab for an inexpensive soil test.

Preventing hollow stem

While there’s nothing you can do about a sudden heat wave, there are many things you can do to prevent hollow stem from happening in the first place:

• Install plants when temperatures are lower.
• Choose smaller varieties rather than fast-growing or giant varieties.
• Plant resistant cultivars.
• Avoid excessive nitrogen or potassium applications.
• Space plants according to seed packet or plant label directions.

Keep your cucumbers and brassicas healthy by allowing them to grow slowly and steadily.