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Growing and Caring for Asparagus

Sunday, February 26, 2023

Gardeners who are looking for a long-time investment in the landscape should consider planting asparagus. An asparagus plant can last up to 15 years, so choosing a spot to grow it should be considered carefully. But keep in mind, gardeners won’t be enjoying fresh asparagus for dinner for a couple of years after planting crowns and three years if planting seeds.


Asparagus is a unique, perennial vegetable requiring minimal maintenance, well-drained soil and a good amount of sun exposure. The edible parts are called spears, and in the peak of the growing season can grow up two 2 inches per day. The spears, or stems, emerge from underground buds at the base of the root system. These buds and roots are called crowns. When left to grow, spears develop leaves and are called ferns.


The asparagus harvesting season is fairly short – usually about two months. Once harvest is complete, the plants need a chance to let the ferns grow to recover and build up energy for next year’s growing season. The fern creates energy that is stored in the underground portion of the plant to produce new spears next year. Gardeners need to care for the ferns following harvest to help ensure plentiful bounty next season.


To help promote a good crop, fertilizer needs to be applied to the crop twice each season – once in late February or early March and again at the end of the harvest season. Promoting vigorous fern growth will replenish the energy reserves in the roots for next year’s harvest.


Before applying fertilizer, remove last year’s dead ferns and move those to the compost pile. Apply a side dressing of fertilizer. Side dressing means applying the fertilizer to the soil around the plant, keeping the fertilizer from contacting the plant directly. Generally, only nitrogen is needed, which is the first number listed on a fertilizer bag. Only apply phosphorus and potassium if a soil test indicates a nutrient deficiency.


The fertilizer is applied at a rate of about one-half to 1 pound of actual nitrogen per 50 square feet. As an example, a bed about 25 square feet, would need one-quarter to one-half pound of actual nitrogen. An organic source of nitrogen in the form of blood meal has a nutrient content of 12-0-0. This means nitrogen makes up 12 percent of the fertilizer by weight, or .12 pounds of nitrogen per pound of fertilizer. If the goal is to apply one-quarter pound of nitrogen to the 25 square-foot asparagus bed, 2 pounds of blood meal will need to be applied.


Consistent soil moisture is important for productive root and fern growth. Apply about 1 inch of water per week. Watering during the harvest season can increase yield in very dry years like Oklahoma experienced in 2022.


Fresh asparagus is a great springtime treat to add to the dinner table. Gardeners can harvest just what they need for each meal or do a bigger harvest and keep the spears in the refrigerator for up to a week.

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