蜜桃恋人

How to Grow Asparagus: The Complete Guide

Organic farming asparagus in black soil gardening plants growing
Photo Credit
KarepaStock/Shutterstock
Botanical Name
Asparagus officinalis
Plant Type
Vegetable
Sun Exposure
Full Sun
Soil pH
Neutral to Slightly Alkaline
Slightly Acidic to Neutral
Bloom Time
Spring
Flower Color
Yellow
Hardiness Zone
4
5
6
7
8
9

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Planting, Growing, and Harvesting Asparagus

Catherine Boeckmann

Asparagus is one of the first plants to greet us in springtime! It’s a perennial, which means that once it gets established, the tender spears will return year after year. In addition, its ferny foliage makes it an excellent ornamental. Here’s how to grow asparagus鈥攆rom planting all the way through to harvest!

About Asparagus

Asparagus can be grown in most temperate regions but more robustly in cooler areas with long winters. The edible part of the asparagus plant is the young stem shoot, which emerges as soil temperatures rise above 50掳F (10掳C) in spring. 

The most important thing to know about asparagus is that you should not harvest it during the first couple of seasons. These plants need to be established before you can harvest sustainably. The patience is well worth it, though. Asparagus beds can be productive for 15, 20, and sometimes up to 30 years. 

Because asparagus stays productive for so long, it鈥檚 essential to plant the best variety available for your area. (See recommended varieties below.)

If you are starting asparagus for the first time, we will plant 5 to 10 plants per person (15 to 30 feet per row).

How Long Does It Take to Grow Asparagus?

As said above, newly planted asparagus plants may take 2 to 3 years to start and produce, so patience is needed truly! After they’re established, however, asparagus can be productive for decades.

In addition, asparagus plants are relatively fast producers, sending up new spears every few days for a few weeks in the spring. The plant produces 陆 pound of spears per foot of row in spring and early summer, so we think it’s definitely worth the wait.

Read Next

Planting

Given that asparagus is a perennial plant that comes back year after year in the same spot, it鈥檚 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 re-planting 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 are planted. 
  • Asparagus is usually grown from 1-year-old plants called 鈥渃rowns鈥 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 鈥楶urple Passion鈥 and hybrid 鈥楽weet Purple鈥, 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.
    1. Soak seeds in water for up to 24 hours before sowing.
    2. Sow seeds in moistened peat or seed-starting soil in flats or peat cups.
    3. Once plants reach 12 inches in height, harden them off outdoors for a week.
    4. 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 鈥渓ittle-by-little鈥 method or the easier 鈥渁ll-at-once鈥 method.

鈥淟颈迟迟濒别-产测-尝颈迟迟濒别鈥&苍产蝉辫;惭别迟丑辞诲:

Once the trenches are dug and the crowns are set out:

  1. Cover the crowns with compost and topsoil, burying the crowns 2 inches deep. Water in.
  2. 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.
  3. 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.
  4. After you鈥檝e filled the trench completely, mound the soil slightly to prevent water from pooling around the emerging spears.

鈥淎濒濒-补迟-翱苍肠别鈥&苍产蝉辫;惭别迟丑辞诲:

  • Some gardeners simply fill in the trench with soil and compost all at once. While it鈥檚 thought that the traditional method results in stronger plants overall, gardeners don鈥檛 typically have any issues result from the 鈥渁ll-at-once鈥 method, either. As long as the soil is fairly loose, the spears won鈥檛 have a problem pushing through to the surface.

Learn how to plant and grow an asparagus bed in our video:

Growing

  • When the trench is filled, we would recommend adding a 4- to 6-inch layer of mulch.
  • The biggest issue with asparagus is managing weeds during the first two years. Asparagus should not have its roots disturbed, so you’ll need to gently hand-pull weeds, taking care not to disturb asparagus鈥 roots. Weeds will become less of an issue as the plants fill in. Mulch around the plant with compost or grass clippings to help retain soil moisture and reduce weed growth.
  • During the first 2 years after planting, asparagus plants need 1 to 2 inches of water per square foot per week. If you are not receiving adequate rainfall, you will likely need to water. Use drip irrigation if possible.
  • Asparagus thrives on a steady supply of plant food. Consider an organic fertilizer during the growing season. Follow the instructions on the label of whatever product you use.
  • Do not harvest the spears in the first or second year (the plant needs time to grow out its root system), but cut down dead foliage in late fall and side-dress with compost.
  • During the second year, side-dress with compost in spring and early fall and cut down dead ferns in late fall. Keep the bed thickly mulched. 
  • During the third year, the bed should be in full production so you can start to harvest asparagus sparingly throughout the season.

How to Transplant Asparagus

  • If you must move asparagus, transplant the crowns in early spring when they are dormant or in late fall before the first fall frost (after the foliage is cut back). 
  • Dig and lift crowns with a garden fork, careful not to disturb the roots. 
  • Divide the clump into two or more pieces. 
  • Water transplants. 
  • Do not harvest heavily in the following year.

Types

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 鈥Jersey Giant鈥, 鈥Jersey King鈥, and 鈥Jersey Knight鈥. Older varieties 鈥Mary Washington鈥 and 鈥Martha Washington鈥 may produce female plants, which are not as productive as the males.
  • In colder climates, 鈥楪uelph Millennium鈥 and other varieties that emerge late often escape damage from spring freezes.
  • In warmer climates, early and heat-tolerant varieties such as 鈥楢辫辞濒濒辞鈥 and 鈥UC-157鈥 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. 鈥楶urple Passion鈥 is tasty but is not an all-male variety.

White asparagus

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鈥攗p 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鈥檚 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鈥檚 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.
Asparagus colors: purple, white, and green
Asparagus comes in few different colors: purple, white, and green! Photo credit: Picture Partners/Shutterstock

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鈥檚 picked, so be sure to eat it within two or three 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.
Gardening Products

Wit and Wisdom

Pests/Diseases

One of the biggest concerns in the asparagus bed is simply weeds. Hand pulling should be done regularly in spring and early summer. Cultivate lightly to avoid damaging emerging asparagus spears. Applying four to 4 to 6 inches of straw in summer also effectively controls weeds.

Asparagus Pests and Diseases
Pest/DiseaseTypeSymptomsControl/Prevention
Asparagus beetlesInsectSpears turn brown and bend in a hook shape; defoliationRemove beetles by hand; dispose of plant matter in the fall where eggs could be housed
Asparagus rust FungusPale green spots on emerging spears become yellow/orange with concentric rings; reddish-brown blisters appear in summer, releasing rust-colored spores that turn black; brown ferns; defoliation; reduced vigorRust requires moisture to spread; avoid getting excess water on spears or ferns. Destroy infected plant matter; choose resistant varieties; ensure good air circulation; avoid planting new asparagus nearby
CutwormsInsectWilting; stems of young spears severed (鈥渃ut鈥) just above soil lineWatch for cutworms and remove by hand; clear away weeds and other plant matter. Find more cutworm prevention tips here.
Fusarium crown rotFungusYellow, stunted, wilted ferns; reddish-brown spots on lower stems, crowns, or roots; rotting spearsDestroy infected plants; avoid planting new asparagus nearby infected site for 5+ years; choose resistant varieties; disinfect tools to prevent spread; avoid overharvesting
Slugs/snailsMolluskIrregular holes in spears; slimy secretion on plants/soilHandpick; avoid thick bark mulch; use copper plant collars; lay boards on soil in evening, and in the morning dispose of 鈥渉iding鈥 pests in hot, soapy water; drown in deep container filled with 1/2 inch of beer, or sugar water and yeast, and sunk so that top edge is slightly above ground; apply a 1-inch-wide strip of food-grade diatomaceous earth as a barrier
  • Asparagus is considered a deer-resistant plant, though deer may nibble on the tips of fresh shoots. A hungry deer will eat almost anything!

Recipes

Prosciutto-Wrapped Asparagus
Asparagus Hummus Served With Dukkah-Spiced Pita Chips
Lemony Asparagus and Spring Pea Salad with Roasted Almonds
Asparagus Tart
Asparagus Frittata
Asparagus Vinaigrette Salad

Cooking Notes

A simple and easy favorite when it comes to asparagus is .

Vegetables
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it鈥檚 not surprising that she and The Old Farmer鈥檚 蜜桃恋人 found each other. She leads digital content for the 蜜桃恋人 website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann
 

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Comments

Linda Schrader (not verified)

7 years 4 months ago

We have very old asparagus. We were told to add salt after season was over. Didn't know if this was a benifit or not.??
Any advice would be appreciated. Thanks

 

We have heard of using salt after the season is over to keep down weeds, but not to improve the health of the asparagus.

Janet (not verified)

7 years 4 months ago

I live in New England. I planted crowns about a month ago (early June) following directions as best I could. It is now early July and the crowns are not showing any bit of green growth. I don't know what I did wrong. Was I too late? Is it too late now to get new root crowns and plant again or should I just wait until next spring? Should I try seeds instead?

Samilyn (not verified)

7 years 4 months ago

Hi Janet,
I got my asparagus planted in early June too because of numerous delays. I actually stored the crowns in my refrigerator for 5 weeks before planting. Figuring I had nothing to lose anyway, I planted the crowns at the first opportunity I had. A couple of weeks ago I was ready to yank them all out and wait until next year to try again, but lo and behold, tiny shoots had finally appeared! I was utterly amazed. Of 10 crowns I only lost one. So, if you don't want to use those beds for other plants, just be patient. I hope your plants surprise you. Best of luck! (PS: I'm in Washington, zone 8b)

Hi, Janet. Yes, it sounds as though you planted your asparagus too late. It should go in the ground in early spring. We suggest you start fresh next year. 

Good Guys Gardening (not verified)

7 years 4 months ago

Thank you for the specific planting guide about asparagus. It is one of the most delicious vegetable in the world.

Pam Stuerzl (not verified)

7 years 4 months ago

I have a patch of asparagus that has been left wild for likely about 20 years. I would like to dig up the crowns and move them to my garden. Any advice on which ones to dig up and how would be appreciated. I live in north central British Columbia so we have a short (100 day) growing season and cold winters.
Thanks

Hi Pam,

That’s certainly an old patch of asparagus, how do the plants look? Healthy? It’s not recommended to transplant old crowns, especially as old as 20 years. They have extremely developed root systems, and the plants would most likely be shocked by the transplant and die. However, gardening is an experiment and who knows for sure what may happen! Try transplanting the smaller crowns into a well-draining, sandy soil. Usually the crowns should be planted at a depth of 6 to 8 inches, but these may like to be deeper. Try planting a few depths between 8 to 12 inches. Water them well and see what happens. Good luck!

Penny (not verified)

7 years 5 months ago

My asparagus plants are on their third year. We had a great crop this year. I have left them to go to fern, but they are now well over 4' tall and the wind and rain have knocked most of them over. Will this damage the crowns? You can see a deep hole at the base of the fern. What should I do if anything?

Your ferns will be OK even if they are laying on the ground. We have heard that some people prefer to steady them with a stake, but it isn’t necessary.