Asparagus (Asparagus officinalis) is a unique crop. It grows unlike any other vegetable you may have in your garden. Although it takes longer than most vegetables to start producing, it will be well worth the wait!
How Asparagus GrowsYou can start asparagus by seed or by purchasing crowns. I prefer crowns because you will get a producing crop within 2 years instead of 3 years if you started from seed.
The edible parts of the plant are called the “spears.” These are technically the stems of the plants. The spears emerge from underground buds at the base of the root system. These buds and roots are called “crowns.” If spears are left to grow, they develop leaves and are called “ferns.”
Asparagus harvest is only two months instead of the entire season. This is because the plants need a chance to let the ferns grow in order to recover and build up energy for the next year. These ferns are what creates energy that will be stored underground and used to produce new spears the following season.
It is a long-lived vegetable. It isn’t planted as an annual like our normal garden vegetables. When choosing a spot, keep in mind that this plant can live up to 15 years or longer.
Like most garden vegetables, choose a sight with full sun. Asparagus does not like acidic soils. The pH it prefers is 6.0-6.7. It likes loamy, well drained soils. Raised beds may be a better option over our traditional garden beds considering our soils are acidic and compact.
If you aren’t going to use a raised bed, amending the soil should take place a year in advance. You can amend your soils with compost, leaf mulch, and other bagged amendments found in stores.
We always recommend getting your soil tested before planting anything. Pick up a soil sample testing kit at your local extension office!
How to Plant
Purchase disease-free, well-rooted crowns. Plant crowns in late winter, after the danger of hard freezes is over.
It’s common to plant asparagus in furrows. Dig a 6-12in deep furrow (trench) for the crowns to be planted into. In heavy clay soils, make the furrows shallower at 6-8 inches.
Crowns should be planted in rows 5ft apart and 12in apart within the row. Make sure the buds are pointing upwards, then cover your crowns with 2-3 inches of soil.
As the plants grow, you may have to add more soil around the crown. Keep some extra soil handy.
Do not harvest asparagus the first growing season after planting crowns. It can be harvested (cut) for a short time the second year.
Once established, asparagus is one of the earliest harvested vegetables in the spring. Harvesting season lasts about 6-8 weeks.
When harvesting your spears, be sure to cut them all the way to ground level. This will reduce the chance of damage to your spears.
Fertilizing and General Bed Maintenance
Each spring (mid-March), right before you see the spears start to appear, you can broadcast a complete fertilizer such as 10-10-10 at 2-5lbs per 100sqft.
Use mulch to suppress weeds in your asparagus bed. Allow plants to grow until the first hard frost, then cut the ferns back. If you cut the ferns before frost, you could see reduced yields the following season.
‘Mary Washington’- high yields and rust resistant.
‘Jersey Giant’- High yields with large spears. Resistant to rust and fusarium.
‘Purple Passion’- purple in color and sweet. Resistant to rust, fusarium, and crown rot.
How Much to Plant
Most asparagus crowns are sold in bundles of 10. The rule of thumb is to buy 10 crowns per 1 family member. So, if you have 3 members in your family that will eat asparagus, purchase a total of 30 crowns.
Lastly, asparagus can add some aesthetic interest to your garden. The ferns give this plant a very unique look and can add some texture to your garden bed. If you happen to get a female asparagus plant, they produce ornamental red berries in late summer that adds some great contrast to the green ferns!
Find more information at caldwell.ces.ncsu.edu or call the Caldwell County Center at 828.757.1290.