Planting, Growing, and Harvesting Asparagus
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Planting
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 (6–8 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.
When to Plant Asparagus
- Plant asparagus crowns in the early spring as soon as the soil can be worked. Many gardeners plant them at about the same time as potatoes.
- Asparagus is usually grown from 1-year-old plants called “crowns” but can also be grown from seed. Starting with asparagus crowns, however, eliminates the year of tedious weeding that comes with starting from seed and will speed up production overall.
- A few varieties, such as open-pollinated ‘Purple Passion’ and hybrid ‘Sweet Purple’, can be grown from seed. Start seeds indoors in spring and set out the seedlings when they are 12 to 14 weeks old, just after your last spring frost.
- Soak seeds in water for up to 24 hours before sowing.
- Sow seeds in moistened peat or seed-starting soil in flats or peat cups.
- Once plants reach 12 inches in height, harden them off outdoors for a week.
- After the last spring frost, transplant the young plants to a temporary garden bed. Once they mature in the fall, identify the berry-less male asparagus plants and transplant them to your permanent planting site, removing the less-productive female plants.
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 and place the asparagus crowns on top of the mound, spreading out their roots evenly.
- Within the trench, space asparagus crowns 12 to 18 inches apart (measured from root tip to root tip).
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:
Asparagus plants are either male or female. Female plants produce berries; males 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.
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.
Cooking Notes
A simple and easy favorite when it comes to asparagus is asparagus soup.
Catherine Boeckmann
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We can’t help you here; there are some 300 asparagus species.
I am gowing asparagus and i am unsure how to harvest seeds from it. Thank You.
Asparagus seeds are inside the red berries that form on the ferns. They are tiny: the seeds number about 19,200 per pound. You can start them in flats or peat up; it takes at least a year to grow a good crown.
Hi, I have four 8 month old asparagus plants in pots that I grew from seeds. I've been keeping them in partial shade and these last six months are the relatively cooler months here in South India. I think its time to transplant them as the pots are small, but I'm not sure where to put them. Temperatures in the next 7 months will hit 85 F to 95 F. Will the pants survive that kind of heat if I plant them in direct sunlight. Or should I pick a shady spot under a tree? Please let me know what you think. Thanks!
Where I live it gets triple digit highs and my asparagus is in full sun doing great. Hope that helps
I live in North Central Minnesota. I just mowed down all our ferned asparagus plants before winter. Will that kill the asparagus or will it be okay next spring? Thank You.
What color were the ferns? If they were light brown, fully dead, then it indicates that the plant is dormant, and it is fine to mow the ferns now. If they were still in the process of dying back, such as a bright yellow, then it might have been better, but not critical, to wait just a bit more, until the ferns wither and turn light brown. As I understand it, the yellow ferns, although no longer making food, still contain nutrient energy to transport to the crowns before the ferns totally die back. It’s best not to cut down green ferns, as they are still making food for the plant; if yours were still green, then hopefully the plant, at this late date, has enough food to get by for the winter and start up again in spring; there might be a chance, though, that the spears next year might be weaker, until the plant can recover; if this is the case in spring, you might avoid harvesting that year, so that the plant can catch up on food-making. Hope this helps!
Have 10 plants in a raised bed, they are about 4-5 feet tall (stalks seem a little thin to me, size of a pencil give or take) Anyway, when I cut these back how far down do I cut? I've heard 2 inches below the soil and 2 inches above. And what is the best fertilizer and type of mulch to overwinter 1st year? I am in Western NY. Thanks
After the first front turns the ferns brown, cut down to about 6 inches above the soil. Weed the bed, and spread a couple to a few inches of compost or dry leaves or the like. In spring, check the soil pH, and amend as needed. Apply a well-balanced (5-10-10 or 8-24-24) fertilizer in the spring. Stalks will be thin for a couple to three years.
I started Asparagus in small pots ( yogurt cups) Now Fall is almost here and it's not planted. Yeeks. Can I plant it outside now? We live in Springfield, West Virginia. What to do so the plants I've babied winter over? I have a cave (very low light) could they be stored there for winter? Put them all in a larger container? Thanks, Lisa
