Asparagus (Crop)

Asparagus

( ah - SPARE - ah - gus )

At-A-Glance Information

The genus Asparagus includes both ornamental and edible species; this page is dedicated to the crop species grown as a vegetable, their young shoots are harvested and consumed. For the ornamental species, visit the page linked below.

Ornamental Asparagus

Asparagus Species and Varietals

The genus Asparagus is the type genus member of the plant family Asparagaceae, and includes five species. The best growing zones for Asparagus are USDA hardiness zones 3-10 or Sunset growing zones 12-24. To find your zone, click here: Zone Map.

Asparagus officinalis (Garden Asparagus, Common Asparagus, Sparrowgrass)
This species of Asparagus is cultivated around the world for its young, edible shoots. It forms an herbaceous, perennial plant that can reach up to 5 feet tall, with stout stems and feathery foliage. Typically, plants are harvested when shoots are young, and plants do not have a chance to grow foliage, flowers, or fruits. They are native to Eurasia. Commonly cultivated crop varieties are listed and described below:

'Apollo'
Attractive variety with deep green shoots flecked with purple hues. Can flourish in warmer climates.

'Atlas'
Hardy hybrid that produces a bit larger veggies, produces a good yield. Dark green with purple.

'Guelph Millenium'
New cultivar from Canada that thrives in tough conditions. Best harvested in late spring.

'Jersey Giant'
Hybrid that produces spears up to a foot tall. Sturdy and hardy plant that does well in most climates.

'Jersey Knight'
Abundant crop of veggies from a hardy cultivar.

'Jersey Supreme'
Hybrid that has a uniform spear appearance. Hardy.

'Mary Washington'
Known for its bright green spears that can reach up to 30 inches tall. Easy to grow.

'Pacific Purple'
Purple asparagus with deep violet spears streaked with green. Mix of plump and thin spears.

'Precoce D'Argenteuil'
Commonly cultivated in France, this cultivar performs well in cool climates and produces green-purple spears.

'Purple Passion'
Deep purple spears that can be almost black towards their tips. Easy to grow.

'UC 157'
Most commonly grown variety worldwide. Cultivated commercially. Green spears.

'White Asparagus'
Refers to asparagus grown in darkness, preventing it from attaining a green color.

Caring for Asparagus

Asparagus is typically grown from 'crowns' which are planted in wintertime, typically between January and March. Although they are harvested each year, Asparagus plants are perennials, and can live for between 12 and 15 years before needing to be replaced. These plants should be situated in direct sun, and ideally receive between 6 and 8 hours of sunlight each day for best harvesting results. They are typically best planted on the North side of gardens, so that their tall fern-like growth does not shade other crops. Soil should be well-draining and not compacted, with an pH of between 6.5 and 7.0. If soil is overly compacted, does not drain well, or is not particularly fertile, it is best to amend the planting site with plenty of organic material and compost before planting. In the first year or two, allow the asparagus crowns to do their own thing. If you harvest asparagus in the first year or so, the plants will not be able to produce enough sugars through the process of photosynthesis to form robust underground crowns. This will mean spindly, underwhelming asparagus spears in the years to come. And nobody wants that. After a few years in the ground, harvesting can begin.

Soil moisture is very important for growing Asparagus plants. They need consistent soil moisture in order to stay healthy year-round, not just during growth and harvesting seasons. They should be getting at least one inch of water each week. Cover the planting area in mulch to increase soil moisture retention, suppress weed growth, and maintain constant soil temperatures.
Pruning Asparagus plants happens at the end of the growing season, typically in fall after the above-ground ferny foliage has been killed by frost. Pruning at this time discourages Asparagus pests such as Striped Asparagus Beetles, and keeps plants healthy. Asparagus grown in fertile soil does not need fertilizing. A simple yearly application of organic compost around the planting are will be sufficient to provide nutrients for the growing and harvesting seasons. A second application of compost can be applied after harvesting stops, in order to allow plants to maximize photosynthesis and increase yields in the next season.

How to Harvest Asparagus
During the harvest period, shoots emerge daily from underground crowns. It is a valuable early-season vegetable, and is well-adapted to freezer storage. Spears are harvested from plants that have been in the ground for at least two years, and when spears are between 6 and 10 inches long (though this height depends on the cultivar grown). They can be snapped off by hand near soil level, or cut from their attachment to the crown. Harvesting should occur every two days during the height of the harvesting season, which is between May and June. After harvesting, store them in a refrigerator standing up in a bin with a shallow amount of water added. Make sure to discontinue harvesting spears after six to eight weeks' time, as continuing to harvest past this cutoff will translate to less production the following year. Good indicators to stop harvesting are slowing spear emergence, spear width that is less than pencil size, and heads that are producing foliage that are less than six inches tall.

Disclaimer: Information contained on this website is strictly and categorically intended as a reference to be used in conjunction with experts in your area. Foraging and consumption of plant parts should never begin without the guidance and approval of a local plant specialist. The providers of this website accept no liability for the use or misuse of information contained in this website.

Propagation

Asparagus can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. Asparagus plants are dioecious, meaning there are separate male and female plants. They will both produce spears for consumption, but only female plants will bear the fruits containing seeds. Another thing to keep in mind is that most hybrid varieties grown in backyard gardens are male, and will not produce seeds. Male asparagus plants tend to live longer and produce more spears, and female plants can produce undesirable weedy seedlings if fruits are not removed before seeds are dispersed. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant (especially if you are dealing with a hybrid variety). To propagate your Asparagus, follow the instructions below:

Propagating Asparagus by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. Although this method of propagating Asparagus is cheap and relatively easy, it does require some patience; when grown from seed, Asparagus will not produce spears until it has had about two years of growth. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
Harvest your seeds in late summer or fall, allowing fruits to turn red and soften before collecting. The fruits on Asparagus plants are held amongst the foliage of plants that are allowed to produce their bushy growth. If growing Asparagus for seed collecting, allow at least one or two plants to develop over the season without harvesting them for their edible parts.
Remove the fleshy red coating, and then rinse the seeds and dry them out thoroughly. If stored properly, they can remain viable for up to three years' time. If planting the seeds in the next growing season, they are best started between the months of February and May, for planting out when they are around 10-12 weeks old. Before planting, soak seeds in lukewarm water overnight.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-8 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Asparagus by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil (any kind will do, though it does need to be well-draining), compost, and pots (12 inch pots will do, and these are only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in late fall, after the last ferns have yellowed and died back. To propagate by division, follow these steps:

Gather your materials. Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the crown. Once you have worked it up out of the ground, lay it out.
Start to tease apart the roots with your gloved fingers. Once the roots are untangled, separate your plant into several pieces, each with plenty of healthy roots attached. Crowns are best planted in springtime, so over the winter the crowns will need to be kept in a mesh or paper bag filled with sawdust over the winter months. Place them in a cool, dark, dry place free of pests and mold.
In springtime, prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divided crowns about an inch under the soil surface and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout. Divided crowns will need about a year or so before they will truly establish themselves in their new space and begin producing spears again.