Maintaining Fern Vigor
Elaine Roddy, Vegetable Crop Specialist, OMAF
Aug 1st, 2003
Asparagus is generally thought of as a drought-tolerant crop. With a root system that penetrates more than 6 feet, it is hard to imagine the plants running short on water.
Looking at the actual root distribution and it becomes obvious that water management in the top 2 ft of the soil is still quite important. Approximately 65% of the asparagus root mass is concentrated in the top 24î.
These shallow roots perform the bulk of nutrient uptake and accumulation. Water availability is crucial to move all nutrients into the plant. Percent of Asparagus Roots by Soil Depth
During periods of water shortage, supplemental irrigation will help to maximize and sustain both fern and root development. Drought stressed asparagus plants will often enter an early dormancy. When wetter weather returns the plants will break dormancy, reducing the carbohydrate reserves for next year's crop.
Research has found that soil moisture stress not only reduces fern growth, but it reduces both the number of spears and the spear diameter.
With irrigation comes leaf wetness and the accompanying foliar diseases. The more frequent the irrigation, the higher the risk. In Washington State they recommend using large water volumes (2-3 inches) on an infrequent basis (>2 weeks) for coarse textured soils.