Spring is here, officially, but that doesn’t mean we should get overly excited and go clean up our landscape beds just yet. However, Asparagus will soon be emerging from previous plantings and new plantings can be started soon.
Planting & Care
Asparagus is a perennial vegetable that will come back every year providing you with harvest annually without having to plant it every year. Asparagus is planted as crowns in the spring when soil temperatures have reached 50 degrees, check your soil temperature at go.unl.edu/soiltemperature. Dig a trench 6-8 inches deep and 12 inches wide and place the crowns in the trench and cover with soil. Do not compact the soil around the crowns and be sure to place the crowns with the roots downward and the buds upward in the soil. In the past, it was advised to add 2 inches of soil at a time as the spears grow upward until you reach the top of the trench, but new research indicates that isn’t necessary and you can just cover all the way back up with soil when you plant.
Once planted, wait to harvest until the third year to give the roots time to become fully established before beginning harvest. Asparagus can be planted from seeds, but it will add one more year to the establishment period before harvest is initiated.
Asparagus needs to be watered when precipitation is not present. It should receive about 1 inch of water weekly, which may need to be supplemented during periods of drought. Ensure that you are watering down to where the roots are, at 6-8 inches deep by using a screwdriver to probe the soil for moisture.
For fertilizer, you should start with a soil sample to check where your soil nutrient levels are when starting the bed and every 3 years after planting. If necessary, a typical garden fertilizer (10-10-10) will benefit plants annually. If you start to notice that the plants aren’t producing as well as they did after multiple years in the ground, it is likely that fertilizer is necessary. Composted manure can be used as well, but that is best added to the soil around the asparagus in the fall to reduce problems with bacteria.
Weed Control
Weeds are one of the most common problems for gardeners of asparagus. For years, many gardeners used the salt water produced when making ice cream around asparagus, this is no longer advised. Asparagus can survive in a high salt condition due to the deep roots, but salt can build up and cause asparagus to die over time. Also, the salt content in the soil can create a crust which blocks water absorption to plants which causes drought stress. Using any type of salt in the lawn or landscape is NOT a recommended practice for weed control in any situation.
The better option for weed control in asparagus would be to use mulch around the plants. Any type of organic mulch will work for weed control around the asparagus including grass clippings, wood chips, straw, or hay. If using grass clippings, be sure that it hasn’t been treated with herbicides or follow the label for length of time to wait after application. Mulch will keep the weeds down as well as hold onto moisture and add nutrients back into the soil as the mulch breaks down. Frequent, light shallow cultivation can be done early in the spring to help with weeds also.
Preen can be used to help reduce weeds in asparagus. Make sure it is the Preen product that is labeled for use around the asparagus and use it in combination with the mulch to help with annual weeds. Pay close attention to the label on the Preen product, it states it can only be used in the early spring before spears emerge.
Another option is to use a glyphosate product over the bed after the last harvest of the year. Snap all the spears off to ½ inch below the soil surface and spray over the bed, be sure there is no foliage or any green growth above the ground. Spray the glyphosate over the bed in the late spring when harvest is complete for the year. This will control most weeds found in the garden.
Harvesting
Harvesting can be completed by cutting or snapping spears off the plant as they emerge and grow to 5-8 inches in length. Harvest for 6-8 weeks or until the majority of the spears are less than 3/8 inches in diameter. When all the spears get spindly, the plant is running out of energy for production and harvest should be concluded to allow the plant to rebuild its resources for next year.
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