Aspiring Asparagus

Posted in Gardening Tips on March 29 2011, by Sonia Uyterhoeven

Sonia Uyterhoeven is Gardener for Public Education.

We eat different parts of plants. Some of the roots that we eat in vegetable gardens are carrots and radishes. Some of the leaves that we eat are lettuce and kale. Fruits are cucumbers and tomatoes. And stems….

In mid summer if you walk by a vegetable garden and see a patch of tall airy fern-like sprays of foliage and can’t put your finger on what it is – then it is simply a matter of timing.

You will recognize this vegetable in the spring as the shoots emerge from the ground before they grow to their full size. What is it? – Asparagus (Asparagus officinalis). By mid summer they have branched out beyond recognition and have an enormous amount of ornamental appeal.

Asparagus is a perennial (zone 2 to 8) that will last up to 15 years or longer in your garden. Make sure that the soil is properly amended with plenty of organic matter before you plant your asparagus since it will be there for a while.

Asparagus prefers full sun although it can handle part shade. Good drainage and rich soil is essential. It grows best in a pH between 6.5 and 7 but will handle a pH down to 6. If your soil is more acidic you will need to lime.

Asparagus can either be planted from seed or from 1 year old crowns (which is the norm). Plant the crowns (the area where the roots and the shoots meet on the plant) immediately so that it doesn’t dry out. If you can’t plant right away store the crowns in the refrigerator and mist occasionally.

Dig a trench for your plants on the edge of the garden where they will not shade out other vegetables – the foliage gets from 5-9 ft. tall. Plant the crowns 4 weeks before the last frost date in your area. Dig a trench 5 to 10 inches deep and generously amend with organic matter. Plant the crowns 18-24 inches apart in rows 3 feet apart.

Make a ridge in the middle of the trench and place the crowns on the ridge so that their roots spill over the edges. It will look like a row of octopuses sitting on a ridge. Cover with several inches of back fill and wait until you see growth before you continue to cover.

Asparagus is dioecious – older varieties such as ‘Mary Washington’ has male and female flowers on separate plants. The female plants expend energy producing seed and are not as productive. In the past people weeded out the female plants and kept the male. These days Rutgers University has produced all-male hybrids that are more productive. ‘Jersey Knight’, ‘Jersey Giant’ and ‘Jersey King’ are three popular varieties on the market.

The Rutgers hybrids should only be planted 5 inches deep. Older varieties are best planted 8-10 inches deep – they are less productive and run into problems if they are planted much deeper.

Do not harvest your asparagus for two years to allow them a chance to get established. During the third year you can harvest for 3-4 weeks and after that you will be able to harvest for 6-8 weeks. Harvest spears when they are about 6-10 inches long in spring.

Asparagus benefit from a good layer of straw mulch in the middle of the summer to keep weeds down and moisture in. Water during dry spell but otherwise they plants are fairly self-sufficient. Weed the bed at the end of the season and fertilize with compost or aged cow manure. Once the foliage dies back you can cut it down for the season.