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Botanical Name
Asparagus officinalis
Grown as
Toxicity
Sun Exposure
Water Needs
Height
Spread
Soil pH
Bloom Time
Flower Color
Special Features
Resilience
Plant Type
Planting
When to Plant Asparagus
- Asparagus is usually grown from 1-year-old plants called “crowns,” planted about 2 to 4 weeks before your last spring frost date. Many gardeners plant them at about the same time as potatoes.
- We do not recommend growing from seed; it takes about three years to mature enough to harvest. If you plant crowns, you can shorten the wait time by a year and eliminate one year of tedious weeding. However, if you’re truly eager to experiment and have a lot of patience and time, our colleague Robin wrote about planting asparagus by seed.
Where to Plant Asparagus
Given that asparagus is a perennial plant that comes back year after year in the same spot, it’s important to select a proper planting site where it will thrive.
- Choose a site that gets full sun (6 to 8 hours of direct sunlight).
- Place the asparagus bed toward the edge of your garden, where it will not be disturbed by the activity of planting and replanting in other areas.
- Ensure the bed will drain well and not pool with water. Asparagus does not like to have its roots get too wet. If you do not have a site with good drainage available, consider growing asparagus in raised beds instead. Learn how to make a raised garden bed here.
- Asparagus thrives in neutral to slightly acidic soil (pH of about 6.5).
- Eliminate all weeds from the planting site, digging it over and working in a 2- to 4-inch layer of compost, aged manure, or soil mix. (Learn more about soil amendments and preparing soil for planting.)
- The soil should be loosened to 12 to 15 inches in depth to allow the asparagus crowns to root properly and not be disrupted by rocks or other obstacles.
How to Plant Asparagus
- Plant crowns deeply to protect them from the cultivation needed for annual weed control.
- Dig a trench about 12 to 18 inches wide and 6 to 8 inches deep. If digging more than one trench, space the trenches at least 3 feet apart.
- Soak the crowns briefly in lukewarm water before planting.
- Make a 2-inch-high ridge of soil along the center of the trench. Place the asparagus crowns on top of the mound, spreading out their roots evenly.
- Space asparagus crowns 12 to 18 inches apart (measured from root tip to root tip) within the trench.
Once you get to this point, you can follow one of two planting methods: the traditional “little-by-little” method or the easier “all-at-once” method.
“Little-by-Little” Method:
Once the trenches are dug and the crowns are set out:
- Cover the crowns with compost and topsoil, burying the crowns 2 inches deep. Water in.
- As the season progresses and spears grow to be 2 to 3 inches tall, add 2 more inches of soil to the trench, being careful not to bury the spears completely.
- Once the spears again grow through the layer of soil, add an additional 2-inch layer of soil. Repeat this process until the trench has been filled to ground level. Depending on how deep you dug your trench, you may need to add soil 1 to 2 more times throughout the season.
- After you’ve filled the trench completely, mound the soil slightly to prevent water from pooling around the emerging spears.
“All-at-Once” Method:
- Some gardeners simply fill in the trench with soil and compost all at once. While it’s thought that the traditional method results in stronger plants overall, gardeners don’t typically have any issues resulting from the “all-at-once” method. As long as the soil is fairly loose, the spears won’t have a problem pushing through to the surface.
Learn how to plant and grow an asparagus bed in our video:
Harvesting
- Skip the harvest in the first year and the second year, if possible. Ideally, wait three growing seasons before harvesting in order to allow the crowns to become fully established.
- If you have young plants, the season may last 2 to 3 weeks. However, established plants produce longer—up to 8 weeks.
- Check your plant every other day for harvest-ready spears. Spears grow quickly and may become too woody before you know it! Once an asparagus spear starts to open and has foliage, it’s too tough for eating.
- Harvest spears when they reach 8 to 10 inches in height and between 1/2 and 3/4 inch thick. (Bear in mind that younger, thinner spears will be more tender, so harvest according to your own taste.)
- To harvest asparagus, simply cut the spears with a sharp knife or scissors at ground level.
- Stop harvesting spears when the diameter of the spears decreases to the size of a pencil.
- After harvest, fertilize your asparagus patch in the early summer. You can top-dress with a balanced organic fertilizer or scatter another inch of rich, weed-free compost over the decomposing mulch.
- Do NOT cut down the remaining ferns in summer or you will ruin your asparagus bed. Allow the ferns to grow and mature; this replenishes the nutrients for next year’s spear production. Always leave at least two or three spears on the plant through the growing season.
- Only cut back asparagus ferns AFTER the foliage has died back and turned brown or yellow. This is usually in early winter after several hard freezes. Cut the ferns back to the ground.
- Fertilize the bed with a 1-inch layer of rich, weed-free compost or manure topped with 3 inches of straw, rotted sawdust, or another weed-free mulch. Clean spears will push up through the mulch in spring.
How to Store Asparagus
- Plunge just-cut spears into cold water immediately to preserve their sugar content.
- Asparagus does not keep for very long after it’s picked, so be sure to eat it within 2 or 3 days from harvest.
- To store, bundle the spears together, wrap the stem ends of the spears in a moist paper towel, and place the bundle in a plastic bag. Store in the crisper drawer of your refrigerator.
- If you have enough space in your fridge, you can also store asparagus by placing the spears in a cup of water. Keep about an inch of clean water in the cup.
Types
Asparagus plants are either male or female. Female plants produce berries; male plants do not expend energy on berries, so they can be up to three times more productive than female plants. For this reason, growing male asparagus plants is often preferred.
- Gardeners in Zones 4 to 6 have a wider selection of varieties, including ‘Jersey Giant’, ‘Jersey King’, and ‘Jersey Knight’. Older varieties ‘Mary Washington’ and ‘Martha Washington’ may produce female plants, which are not as productive as the males.
- In colder climates, ‘Guelph Millennium’ and other varieties that emerge late often escape damage from spring freezes.
- In warmer climates, early and heat-tolerant varieties such as ‘Apollo’ and ‘UC-157’ produce well before the weather turns hot.
White asparagus is not a variety but simply asparagus grown in the absence of sunlight to prevent chlorophyll from developing. White asparagus is slightly sweeter but has less fiber than green asparagus.
Purple asparagus is bred to be purple in color but turns green when it is cooked. Purple varieties tend to have thicker spears, but fewer of them. ‘Purple Passion’ is tasty but is not an all-male variety.
Comments
i planted a 2 year old crown i have 2 small foot tall ferns directly above it and another fern 2 feet away where water pools
can asparagus be planted this late in the year. Late June or early July,or am I better to just wait and plant next spring Thank You
Odds are not in your favor now. Plant next spring. Set out seedlings when they are 12 to 14 weeks old, just after your last spring frost. Or, start with asparagus crowns (dormant roots of 1-year-old plants) to eliminate years of headaches that come with starting from seed.
I planted Mary Washington(female) asparagus roots a little over two weeks ago (May 29, 2013). I dug a 6" trench and laid the crowns down and covered them with 2" of soil mixed with a little sand. I haven't seen any spears yet. How long does it take before I start to see something? I live in PA and we have had a rainy couple of weeks. The temperature has been in the 70's. The water has been draining through the trench. Thank You!
You should start to see spears in a few more weeks. Rain or temperature may affect when they emerge--make sure there is good drainage. If nothing comes up for a while, you might check a crown or two to see if it has rotted or looks diseased.
(Do not harvest any spears that appear during the first year after planting; allow them to develop into ferns, so that the plant can produce food to help it to become established. The second year, harvest lightly. Third year onward--harvest normally.)
I have a great asparagus bed, and we have enjoyed much good foods, from it, however, I need to know about whether the fern is the only part to leave, or if, for example, when we were not in town, the stalks got too large, to eat, should I leave them also, or go ahead and cut them down, as well...? Basically, do both male and female plants, grow thru the fern, or is the foliage, that gets too large, as well..? I just dont want to cut the large stems down, if they are also feeding for next springs harvest. Thanx for any help as to whether it is the fern ONLY, that I should leave...?
When the recommended time slot for harvesting is over, allow everything to grow. All stalks, whether large or small, or from male or female plants, will develop into ferns. Leave the ferns over the summer and allow them to brown and die in fall before cutting them near the ground.
Both male and female plants will produce ferns; both plants will flower. However, the female plants will also produce berries (if there is a male plant nearby for pollination). In general, female plants with berries may have thinner stalks than males because some of the energy goes into producing the fruit. Some hybrids are all-male; these usually have more vigor and produce thicker stalks.
I have inherited a mature asparagus patch in a newly purchased house. I have enjoyed fine asparagus for weeks now. However, I do not know how to maintain the patch OR, importantly, if I should stop cutting the crop & allow a few to grow (to provide carbohydrates for the root system). What should I do - I don't want to 'damage' the crop and / or hinder growth for next season. Help!
Our asparagus bed is about 4 years old and producing well but this year we had great rains in the spring. We have little plants coming up from seed. Should I pull them up?
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If you wish, divide asparagus roots during the winter after the tops have been removed. To divide, use a saw to cut the clump into two or more pieces. When you divide the crowns, you are creating new individual plants that you can replant--either enlarge your asparagus bed or create a new one.