Levels of Difficulty Growing Food Plants

Gardeners tend to treat all food plants as though they have the same nutritional requirements, when in fact; they fall into three broad groups with light, medium and heavy nutritional needs. This grouping is determined by the degree of inbreeding and refinement required to develop different varieties and by timing and seasonality. Gardeners that can sort food plants into groups organized by the difficulties in growing them, increase their success at consistently putting food on the table.

The chart below ranks members of the cabbage family according to growing difficulty and levels of soil nutrition needed to grow them successfully. Broccoli is rated both moderate and difficult to grow depending on seasonality. Here, the “window of opportunity” for planting broccoli in spring is very small, but in fall, the only caution is having adequate soil nutrients to accommodate broccoli’s rather small root system.

Root growth studies show that food plant varieties that are genetically closer to their wild ancestors have root systems that are far more capable of foraging for moisture and nutrients. As a result, they require less concentrated soil nutrition and if given adequate root room, by not crowding them, can produce food with less irrigation.

Root development in Kohlrabi and Kale are about the same and demonstrate the ability of their wild ancestors to mine the soil. In contrast, Cauliflower has a limited root system in relationship to above ground growth and requires careful feeding and irrigation to produce quality food. Broccoli has a root system similar to Cauliflower, but is more tolerant of clay soils.

When growing the more refined food plants there are reasons to select high quality hybrid seed over heirlooms and traditional open pollinated varieties, or searching for heirlooms that still retain their original vigor. (subject for a different article)

till next time,

Darrol Shillingburg – January 2008
Doña Ana Extension Master Gardener

Root horizons redrawn from: Root Development of Vegetable Crops,
John Weaver, 1929


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