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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.
I planted in May of 2012 and did not cut down the asparagus in the fall. Should I cut them now or let them go? Having planted in 2012 can I harvest this year or should I wait til next year 2014?
The rule of thumb is bending: some sources now say that is can be beneficial to harvest spears in their second year of growth (that it's not necessary to wait until the third year). Harvest by snapping off, not cutting, spears of 7 to 9 inches height that have tight tips. Leave the tops, or fern, as long as they are green. If the plants are healthy, you can leave the fern tops through the winter, then cut or mow them down before new growth appears in spring. We hope this helps!
will new spears coming up freeze like other veggies in early spring with temps. down about 32 ?
Hi, Yes the tips & upper stalk will freeze & when the warming sun hits it, the spear will shrivel & wilt. Kind Regards, Rod
I just purchased my first asparagus to add to my expanding garden. I have a nice spot selected for it to mature under a cedar tree - we are in zone 9b and I don't expect drainage to be an issue. Does anyone have knowledge about the success of planting asparagus near an established cedar tree?
I suppose you could experiment! You need to ensure the asparagus receives enough sun and especially soil moisture. Often, areas around cedars are acidic, dry, and shady--so drought-tolerant shade plants such as hostas do best. Also, take care not to dig too closely to the cedar tree and its root system.
I'm continually learning my raised bed gardening. Planted asparagus 3 yrs ago. Actually the 1st year I got several tasty asparagus. My neighbor said, "NO NO, don't pick the first year"...so I quit, fern sprouted and ever since, I only get fern and I don't know what to do. Also, how do I acidify my soil safely?
To acidify soil use agricultural sulfur. A soil test will tell you how much to use to move the pH one point. For our soil in PA, it takes 3.5 lbs per 100 sq ft, to go from 7.2 to 5.5. Somewhere around a pound per point. HOWEVER:!! Asparagus likes to be around 7 so you do not need to acidify for asparagus if you soil is near 7. Blue berries like 5.5, red and pin oaks 4.8 to about 6. Check your crop before changing the pH. Different areas of the garden may be different pH. Potatoes like 5.5 or so. Do not add lime to the potatoes, you get marble size potatoes. I changed the pH to 5.5 for my potatoes and grew 1/2 to 1 pounders.
Bonnie, Check your soil's pH. (Testers are available at nursery stores.) In our pH Preference chart (p. 272 in The 2013 Old Farmer's Almanac) we say, "Acidic, or sour, soil (below 7.0) is counteracted by applying finely ground limestone, and alkaline, or sweet, soil (above 7.0) is treated with sulfur." Lime makes soil sweeter, sulfur makes it sour. Asparagus like soil at pH 6.0 to 8.0, generally speaking.
This first question does not have an easy answer--there may be too many variables. Your neighbor was correct, but with a couple of years now passed, you should get something productive. It may be that next year (now your third year), that you will get results. Of course, the wrong pH may be the problem. Or the amount of nutrients in the soil; asparagus loves rich compost. Its roots are long—possible around six feet; could they be stunted by something in the location?? a wall, tree roots, or other? (One of our editors wanted to use asparagus as a foundation plant and, upon learning of the root length, pulled it out before it matured--but suggested this possibility.)
Lack of spears may just be poor growing conditions. This occurs in areas that have warmer climate. Asparagus need a cold "rest" period; lack of one can influence the plant's ability to store food and so grow successfully the next season. Alternatively, contact your local extension service; we list all of the states here: http://www.almanac.com/content/cooperative-extension-services
We hope this helps!
When should I cut my ferns down.
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