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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 have a big asparagus bed that is over 30 years old. It still produces lots of ferns, but most of the spears are pencil-thick, and some roots seem to have died off. Every year I spread on a thick layer of compost/ seaweed. All I've read says that asparagus beds last for many years (this site says 20 or more), but none suggest what to do with an old bed. Do I dig out the old roots and start again? Leave a few plants and till deeply all around them? Abandon the site? No article has told me.
Some people would love to get pencil-thin spears!
Have you checked the pH? Asparagus likes lime. Everything you're doing sounds good...so it might be the pH (you can get an inexpensive kit at a nursery). Digging out the roots would be a lot more work than you might think; roots could be 4 to 6 feet or more!
Then there is this (a few questions below yours): you might want to fertilize: Scatter 2 pounds of 10-20-10 fertilizer (or its equivalent) per 20 feet of row before growth begins in the spring. After the last harvest, apply an additional 1 to 2 pounds of 21-0-0 (high in nitrogen) per 20 feet. Always water the fertilizer into the soil.
With this, your plot should come back to life.
Bought a ranch once with a huge asparagus bed. Previous owner forgot to tell me. No defined rows, very old. It was late October and the whole area looked like dead weeds. So I started to pull them. They didn't budge. Got heavy gloves. No luck. Finally got a shovel and dug roots all day. It was impossible to get it all. Finally gave up. After the snow melted and I had long since forgotten those weeds, I was stunned by the prolific production of fat asparagus. I don't think thinning an old bed and loosening the soil could possibly hurt. Lived there a decade, it always produced plentifully.
My only complaint about growing asparagus is that I couldn't manage to get much in the house. I ate it all raw as I picked it. Had the same problem with the peas and of course the strawberries.
We just bought a home which has a raised bed of asparagus. Right now there are dried stalks about 3-4 inches sticking out of the ground and the bed is covered with dried leaves. What am I supposed to do with this? I’m not sure if I should remove the leaves or just let it be. Thank you
I have had asparagus beds for decades and always pull out the 3" dried stems once the ground thaws. They *could* stay, but get in the way when harvesting new spears. Asparagus hates competition, so a thick mulch of leaves is good, but loosen up any areas where the leaves are thickly packed and might bend over the new shoots. I put piles of sandy seaweed on top each fall and find the top layer can get hard and crusty by spring, interfering with the new growth. But it's easy to pull the crusty layer aside and the rest of the seaweed is well-rotted and mushy so the asparagus can get through.
I have my asparagus planted in a raised bed. This last year I had a hard time battling grass/weeds from growing all over in there. It doesn't seem to matter how much I try to manually weed! Is there a tip to discourage weed growth in my bed? Is it possible to possibly spray in the off season? Thanks!
The best way to keep out weeds is to mulch. Several inches is not too much. Without it, you'll be battling weeds forever.
As for spraying, what's the point of growing food if you're going to put chemicals into the soil (in the food)? If you can get head of the weeds somewhat and mulch immediately, you'll do yourself and the plants a big favor.
And edge the plot. Put a hard line on the edge of it so that grass and weed roots can not reach in. (You'll need to do this every year.)
While I commend anyone who follows the instructions for planting and harvesting asparagus or any plant, I have to wonder why is it that we have gone completely against nature in gardening. Asparagus does not require babying. Plant it where you want it to grow and it either will or won't thrive. I have tossed roots on the compost pile, put them under tomato plants, in raised beds and pots, or just on the ground and covered up and guess what, they grew and multiplied. I cut off the stems the very first year on new roots and they don't have a problem. Before you say well, it is your climate, I will say no, Oklahoma is no better or worse than any other place for weather conditions. I have found that if you have adequate water and sun, everything else will come together. Leave the ferns all winter, just like in the wild, and lo and behold, you will be harvesting great tasting sticks before you know it.
Do not over think your Asparagus needs. In eastern Washington it grows wild in the Apple Orchards and nobody bothers to maintain it. I can wander through a field and harvest a five gallon bucket in less than an hour.
Once the asparagus is a 3-4 years old, when do you fertilize, what numbers (10-20-10 ?), and how much?
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