How to Grow Asparagus

KitchenGardener Magazine, archive

147 users recommend

The edible stems of asparagus rise directly from the ground. Spears that are about 8 in. tall are ready to harvest.

Susan Kahn

Snapping of the spear by hand is easy and protects the plant. You can use a knife, but be careful not to damage developing stems.

Mike Sinclair

At the end of the harvest, allow the asparagus plants to form ferns. These help transfer energy to the roots for good spear development the next season.

Ruth Dobsevage

The edible stems of asparagus rise directly from the ground. Spears that are about 8 in. tall are ready to harvest.

Photo: Susan Kahn

Add Comment
Print

My family didn’t grow asparagus when I was a child. We found it. My dad had a sharp eye for the tender green spears that grew wild along roadsides near our home in Piqua, a wisp of a town in southeastern Kansas. He could spot even a single spear when he took the family on Sunday afternoon drives. He would stop our Plymouth Fury and gather the crop.

I developed a passion for asparagus, too. Only now, though I fondly remember those asparagus hunts, I find it much easier to simply step out the back door of my house and snap a few delicious spears from the bed in our garden. When I first planted asparagus, I was a little intimidated by all the folks who said it was hard to grow. Starting a bed does take more work for asparagus than for many other vegetables. But after 15 years, and expanding to 20 acres for commercial production on our farm in Lawrence, I know asparagus is one of the tastiest, easiest vegetables you can grow.

Long lives the bed of crowns

Asparagus is a perennial crop, its long green fingers coming up year after year. So when you make your bed, do it carefully. Your asparagus may be growing in it for 20 years or more. A sunny, well-drained part of the garden will yield the best crop. Asparagus, a good candidate for raised beds, should be planted in soil with a pH of 6.5 to 7.5. I’m lucky my patch was once a cattle feed lot, so I rarely add fertilizer, but people with poor soil may want to fertilize lightly.

Consider weather in selecting a variety. New hybrid asparagus varieties abound. The old standard ‘Mary Washington’ has long been good, but research and breeding have produced some fine alternatives. California varieties tolerate the heat better and keep a nice, tight tip, even above 80˚F. I prefer ‘U.C. 157’, a University of California plant, because we can get many hot days in late spring. New Jersey breeders are offering “all male” plants, which yield more than female plants since they don’t use energy to produce flowers and seeds. In my garden, the ‘Jersey Giant’ tips tend to loosen if the temperature gets above 80˚F, resulting in many undesirable spears.

Seeds vs. crowns. You can start your asparagus with seeds, but they take six weeks to germinate and add another year of growing time before the first harvest. So most people start with the asparagus crown, the root mass and buds.

When buying crowns, look for fresh, firm-fleshed roots. If they are shriveled or feel like paper, they may be old and won’t produce well, if at all.

	Most people start their asparagus from crowns, not seeds. The root masses should be fresh and firm. Dry sections of the roots can be pruned before planting.
	Deeper plantings tend to produce thicker but fewer spears.

Plant crowns early. Crowns should be planted while they are dormant. That can be as early as late winter. They should be planted when the ground is workable, between frosts. As long as the crowns are covered with about 2 in. of soil, they won’t suffer in hard freezes. They can be planted as late as mid-spring, if plump, healthy roots are still available.

A few crowns can be planted merely by digging individual holes for each plant. If you want to plant more, dig a trench. If the soil is heavy clay, the trench should be deep enough to accommodate a layer of compost or other organic material under the crowns. The optimum depth to plant crowns is 6 in. to 8 in. Shallower plantings yield many spindly spears, while those planted deeper produce fewer spears of larger diameter. Place the crowns in the furrow, and cover initially with 2 in. to 3 in. of soil. Keep adding to the trench as the spears emerge. By season’s end, it should be filled. You can fill the trench completely at planting time, but by doing it gradually, you move the dirt and control the weeds.

Asparagus stays healthy with breathing room. Space the asparagus crowns so you get as many plants as possible in a small area, but still allow for good air circulation to protect against disease. I plant my crowns 15 in. to 18 in. apart in rows 5 ft. apart. Figure on 10 plants for each person in the family who loves asparagus. This ought to enable you to harvest enough at one time for a meal.

Modest care pays dividends
When you’ve established your asparagus bed, the hard part is finished. Still, you must follow good culture practices to assure successful crops.

Weeds must be controlled. This can be done mechanically with a hoe, cultivator, or rotary tiller. To avoid damaging the asparagus roots, don’t till deeper than 2 in.  Weed-blocking fabric and mulch will also help. Many gardeners use coarse salt to keep the weeds out. Asparagus tolerates salt, while most other plants don’t.

Except under almost desert conditions, asparagus, with its extensive root system, doesn’t need irrigation. I’ve learned that asparagus drowns much more quickly than it dies of thirst.

Asparagus does, however, need to be protected from pests. The asparagus beetle can nibble on spears and lay dark eggs along the surface. Unless a great amount of asparagus is grown in your area, this is mostly just a nuisance. Scrape off the eggs with your fingernail.

Fungal diseases like asparagus rust, which first appears as small reddish-brown spots on stems, can be treated with fungicides. The new hybrid varieties, however, resist disease.

A royal harvest worth the wait
It takes time to grow accustomed to the asparagus harvest cycle. Although the harvest is about six weeks long, it’s over just as many people start thinking about local summer produce. The asparagus harvest in Kansas usually starts about the middle of April and runs until the first of June. Spear growth depends on temperature. If it’s cool, the asparagus may need to be harvested every three days; if hot, every day.

Older varieties had to grow for three seasons before they could be harvested. With the increased vigor of the new hybrid varieties, gardeners can harvest for about two weeks during the first season, a year after planting. A light harvest seems to stimulate the plant to produce more spears. A full six-week harvest season may follow in year two, provided the average size of the spears is larger than a pencil.

Harvesting is a snap. Spears should be harvested by hand when they are 6 in. to 8 in. tall and the tips are still tight. I recommend snapping asparagus off at soil level. This severs the spear at the junction between the green tender tissue above the ground and the white woody tissue below. All of the stalk you get is edible, and you won’t injure spears that have not yet emerged. You can use a knife to cut the spears just below the surface, but be careful not to damage the developing spears and the crown.

If you plan to store the asparagus for several days, leave some of the white, woody base. It restricts water loss and helps preserve the upper spear.

Fern formation is critical to next year’s growth. The asparagus will keep growing throughout the summer. But difficult as it may be, you must stop harvesting so some of the spears can go to fern, the stage when the tips turn feathery.

Ferns should not be removed from asparagus plants until after several killing freezes. I often recommend leaving the tops for winter mulch. This mulch can catch snow and protect the plants from severe cold, while adding moisture. More important, however, the ferns also transfer carbohydrates and energy to the roots by photosynthesis. This process is crucial to the development of spears for the next year's harvest.

Snapping off the spear by hand is easy, and it protects the plant. You can use a knife, but be careful not to damage developing stems.		At the end of the harvest, allow the asparagus plants to form ferns. These help transfer energy to the roots for good spear development the next season.

Add Comment Print

How to Grow Cilantro

Back to List

Zesty Garden Pickles

Comments (6)

ecgberht writes: Asparagus ... the bane of my existence - I think until today. I had heard for so long how hard asparagus was to grow. I've been trying in a 6 x 4 bed for years with almost no success. But roaming the web, now I read how easy it is to grow and how hardy the plants are. I am now convinced those posters are right!
First, I determined that my soil was not right. This was a raised bed that existed when my wife and I bought our house (along with two other larger raised beds). I read how asparagus likes loose somewhat sandy soil with lots of compost so I decided to dig up what was there and create the environment I needed. I did that this weekend. What I found was, that there were just three or four inches of top soil and then clay! Solid clay. No wonder my asparagus wouldn't grow. I'd like to get some feed back from anyone who has experience as to my "perscription" for the soil. Here goes:
Removed the existing topsoil and saved it.
Dug down and removed the clay to a depth of about 18". (In one spot, I used a long-nosed spade and a post-hole digger to see how much farther the clay went down - I was able to dig down another 10 inces or so and still solid clay!)
My six by four foot bed now looked like a big bath tub with clay sides and bottom.
Put the old topsoil back in the hole first after removing the surviving asparagus crowns (about nine of them). Interesting thing about that topsoil - it was full of little bitty roots of all varieties (probably mostly weeds) - but zero, and I mean ZERO roots in the clay!
Mixed with the old topsoil, in the bottom of the hole, three 50 pound bags of gravel for drainage.
Layered fresh garden soil (in bags made for flowers and veggies) two cubic feet with 25 pounds aged manure and 50 pounds sand, well mixed together - two layers.
That brought me within six inches of the top of the raised bed. Laid in my surviving crowns and some new crowns and watered in.
Then covered with more top soil and some more sand. I did not want to add more manure because I was afraid of burning the plants with direct contact.
So, what does anyone think my chances are?! I think they are pretty good. The reason I was struck by the hardiness of asparagus is that it did ANYTHING at all in that clay soil with so little topsoil. One crown was big enough to divide. After digging them, I dunked in a bucket of water to remove all weeds and mud (a great tip from one site) and found that some of the soil up underneath the crown was clay! Again, if these could survive in these conditions they should love their new home. The new crowns I planted were Jersey Giant. I still have room for about eight more plants so would appreciate any feedback on that as well.
Posted: 5:59 pm on April 7th

Jackie24 writes: I've been searching for some articles on how to grow asparagus/vegetable farm. I'm very much satisfied about this information from http://farmingeek.org and http://vegetablegardener.com. Your articles are much appreciated. Thanks and I hope my crops will be successful.
Posted: 4:25 am on February 23rd

wildgarden writes: I looked up your town on google earth and it has more streets than mine (Luggate Central Otago NZ)
We grow asparagus just for us to either eat raw or if it lasts long enough cooked. I dont think it grows wild in NZ My husband was more interested in the car your father had but he does do most of the vege gardening. We are not organic but dont use sprays or artificial fertilizers
wildgarden
Posted: 9:57 pm on October 14th

cocovette writes: OH MY GOSH! I thought we were the only ones who found asparagus on the side of the road! On our way to church in the fall our father would point out asparagus that had "went to seed" and he would tell us 3 kids in the back seat to remember where it was for spring and sure enough it was always there! We lived in Michigan and the side of the roads were loaded! Thanks for a great memory.
Posted: 11:52 am on April 5th

petuniababi writes: This was a very interesting article.It has made me want to grow a asparagus garden and i have never eaten it! Would it be alright to use an old truck tire as a raised garden for it?If not i will get my husband to till me a spot for it.He's gonna love that:)
Posted: 12:01 pm on March 16th

curryleaf writes: Very timely article. I planted my first crowns last year. Good to know that I could potentially harvest a bit this year "gardeners can harvest for about two weeks during the first season, a year after planting. A light harvest seems to stimulate the plant to produce more spears. A full six-week harvest season may follow in year two, provided the average size of the spears is larger than a pencil."

Even though the asparagus took up a lot of space in the garden last year and I didn't get to eat anything, the fern-like fronds were beautiful--especially when red berries emerged late in the season. The unique-looking plants drew many comments and questions from fellow gardeners in my community garden.
Posted: 8:41 am on March 16th

You must be logged in to post comments. Log in.