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Growing Asparagus
October 12, 2016

Crockett's Victory GardenI've only started two asparagus beds in my lifetime. If you don't move from place to place, starting an asparagus bed is something you should only have to do once. The late Jim Crockett commented in Crockett's Victory Garden (pg 70):

Once during a trip to England I visited the garden of Sir Joseph Hooker, the first curator of Kew Gardens, and found an asparagus bed that was 118 years old and, thanks to Sir Joseph's diligent soil preparation, still producing. You may not plan to pass your asparagus bed along to your children and grandchildren, but even the short-term success of your asparagus will be in direct proportion to the care you take in preparing the soil.

Our current 3.5' x 15' asparagus bed was planted in 2006 and is producing more asparagus than my wife and I can eat. A second asparagus bed behind our property that we now care for is well over twenty years old. For years, it was mowed down about twice a summer by a farm renter who didn't know what was there. When we took over care of the area, a little TLC and a lot of compost brought what we call Bonnie's Asparagus Patch (after the landowner) back to life. With two productive patches of asparagus, we give a lot of it away to friends, family, and my wife's co-workers. We freeze a little for winter use, but there's nothing quite like freshly picked asparagus. We're obviously blessed to have all the asparagus we can eat...for about six weeks each spring.

Our raised bed of asparagus Bonnie's Asparagus Patch

Planning

As mentioned earlier, soil preparation of the site for your asparagus patch is super important. While it might not be practical or timely for most folks, preparing ones asparagus bed the fall before a spring planting would be ideal. That allows the soil amendments added some time to work and for the ground to settle. But for most of us, the soil prep and planting all gets done in just a few days.

The site for your asparagus patch should, like most garden spots, receive a bare minimum of six hours of direct sunlight a day. The soil should be well drained, fairly level, and fertile, although you can improve your soil a good bit during soil preparation.

Narrow asparagus bedI prefer a somewhat narrow bed for asparagus, allowing one to work all areas of the bed from the ends and sides without ever stepping into the bed. A thirty-six to forty-two inch wide bed should give enough room to plant two rows of asparagus down it. Even with our narrow bed, reaching the center of it in mid-summer through a dense forest of stalks and itchy foliage to weed and fertilize is a bit difficult.

Commercial field of asparagusOf course, it is possible to go big with an asparagus planting, spacing rows two to five feet apart to permit mechanical cultivation. I stopped and took a few shots of a large field of commercial asparagus a few miles south of us in 2011. I estimated the field size to be larger than 30 acres, and it is still there today.

If you're going to put your asparagus in a raised bed, build the raised bed before planting your asparagus. I did that one backwards with our last asparagus bed and severely damaged some of the asparagus roots when installing the raised bed several years later around the planting, even though the sides were six or eight inches away from where visible stalks had grown the previous year. Asparagus roots travel a long ways underground.

Soil Preparation

Crockett recommends digging out the prospective bed about a foot deep. When I started our bed, I went a few inches deeper, retaining the dug soil on an old tarp I spread by the site. While twelve inches may seem pretty deep, you need to then work the base of the bed with a heavy garden fork, loosening the subsoil. While doing so is a good time to add sphagnum peat moss, lime (if necessary and also to neutralize the acid peat moss), fertilizer (something heavier on the PK than N of NPK such as 10-20-20), and possibly even some gypsum to help break up clay soils, although that use of gypsum has been heavily discounted in recent years. If you're lucky enough to have a good supply of compost, add it into the mixture. Asparagus totally loves compost!

For our 2006 planting, I actually drove our rototiller down a sloped end of the bed to loosen the subsoil. The machine about beat me to death as I worked soil amendments into our heavy clay subsoil. I think using a garden fork might have been easier!

Then you'll want to return about half of your dug soil to the bed, mixing in some balanced fertilizer (12-12-12), possibly some peat moss if the soil is heavy, and lime if necessary to maintain a soil pH to about 6.5-7.0. Walking over the bed a bit to firm the soil is a good idea if you can't let the soil settle naturally for a week or so.

If you're familiar with the practice of double digging, you might get by doing that to prepare your bed. I've double dug a couple of garden beds, but never could get as low in the soil as I would want to prepare soil for asparagus.

Asparagus Plants (Roots)

Direct seeding of asparagus seed really isn't recommended. The seed is a hard seed that needs to be scarified and stratified before it will germinate well. Growing your own asparagus transplants is an option (I've done it twice. I'll tell how later on.), although you'll probably get to pick asparagus far sooner by buying the best one year old asparagus roots (crowns) you can find.

Lay the asparagus crowns on the soil in rows about eighteen inches apart, spreading the roots in all directions. Spacing in the row is an interesting subject. The general recommendation is to space root centers ten to sixteen inches apart in the row. Some sources suggest a planting as close as six inches apart in the row can be successful. It takes more crowns but produces a fuller bed earlier.

Completely cover the roots and crowns with soil, mixing in peat, lime, and balanced fertilizer (be gentle with this application and don't let the fertilizer touch the crowns). You'll want about three to four inches of soil over the roots. Leave mounds of extra soil along either side of your rows, as when your baby asparagus shoots emerge, you'll want to push soil around them when they get just a little size on them (about 8-12" high).

Thoroughly water your planting, but don't turn the soil into muck with too much water.

Care

Asparagus in second year (2008)
Asparagus in 2012 (raised bed)

Though the first season, keep your new asparagus bed as weed-free as possible. The foliage of the asparagus plants will help some as the plants fill out, cutting off a good bit of the sunlight necessary for some weed seeds to germinate. But you'll probably still have some weeds emerge. Lightly fertilize the bed between and around the stalks at least twice through the first season when you weed, being careful to not get fertilizer within six inches of visible asparagus stalks. Use either a balanced or PK heavy fertilizer. Note that some bone meal won't hurt things, either. An inexpensive soil scratcher (hand cultivator) has proved to be my best tool for cultivating, fertilizing, and weeding asparagus. And heavens, if you're lucky enough to have compost, use it and go light on or totally skip the commercial fertilizer.

Winter Comes

Clearing asparagus stalksWhen fall frosts and freezes brown out your asparagus stalks and foliage, cut the stalks off at ground level. (I use lopping shears for the task.) The cut stalks should be composted or disposed of, as they may carry disease and/or harmful insect eggs. Leaving them on your new asparagus patch could cause trouble in the future. This practice should become a fall routine, often cheerfully assisted by young children or grandchildren. Our grandkids seem to love piling the dead asparagus stalks into our garden cart or pickup truck and dumping them off at a convenient spot.

Since asparagus stalks are rather woody, we usually don't put them into our compost pile. We find a hole somewhere around the property that needs fill and the stalks go there. Dumping them that way has produced some interesting volunteer asparagus in unusual places. If you are fortunate to have a chipper/shredder, the stalks should compost just fine.

Compost for asparagus patch Asparagus patch covered with compost

With the asparagus stalks and trash cleared from the planting, it's an ideal time to spread two or three inches of compost over the asparagus patch. Our asparagus patches end up taking almost all of the compost we're able to generate each year from garden trash, extra grass clippings, and kitchen scraps. Since our compost piles frequently don't heat up enough to kill all the seeds in them, we often have to pull volunteer tomato, cucumber, or other vegetable plants when weeding our asparagus beds.

Patience

One of the quickest ways to kill a new planting of asparagus is to give into the temptation to start picking tender, tasty asparagus shoots the next spring. Okay, we all will take at least one very small mess of shoots for a first asparagus feast, but that should be it. Your asparagus roots need to build their strength in the second year to be ready to give you abundant harvests of asparagus for years and years to come. Just one light picking, mind you!

First Harvest

AsparagusIf you've started your asparagus from roots, it should support several light pickings in its third year. Use your fingers to snap off the shoots that are pencil thickness or fatter at ground level. If they don't snap there, move up a bit, as asparagus too tough to snap won't be very tender when cooked. You can continue picking until your shoots get thinner than pencil width. When that happens, the plants are telling you that it's time to quit picking, cultivate and fertilize, and let the patch begin growing and building strength for the next spring picking. I find that our asparagus patches. when fully foliated, to be a pretty addition to our lawn and garden areas.

The timing of your asparagus harvest will depend on your locale. For us here in west central Indiana, it usually begins sometime in April and runs through much of May. We pick for about four to six weeks each spring, leaving thin shoots behind and only picking pencil to fence post (hey, they get almost three quarters of an inch thick sometimes) sized shoots. Eventually, there are only a few shoots that could be picked each day, and that, to me, is a sign that it's time to end our annual spring asparagus harvest. By that time, my wife, Annie, and I are usually sick of asparagus. Just two or three weeks later, we're again craving the delicious spring treat.

Successive Harvests

Once you get past that third year, asparagus is pretty dependable, unless you run into drought, insect, or disease problems. As long as you don't overpick too long in the spring and weed, cultivate, and fertilize your asparagus patch several times each summer, your asparagus should continue to produce for many years. I occasionally wonder if someone is still harvesting the first asparagus patch I started in the 1980s.

I had a hip replaced in May of 2015 and couldn't do much gardening that summer. One job that got left out was our usual practice of spreading compost several inches deep over our asparagus patches. Our harvest in the spring of 2016 was much shorter and with less volume of good shoots than in past years. Ones asparagus patch has a way of reminding one to practice good fertilization.

One change in fertilization technique with older asparagus is to shift to higher nitrogen fertilizer applied after harvest ends. Switching to something like 20-10-10 is appropriate. We actually just use 12-12-12 on our asparagus, plus lots of compost with good results.

An Oddball Suggestion

MaxicropFor years, I tried to grow good peppers. Our transplants always took hold and grew well until they blossomed. Then they'd begin to fade and die before maturing any peppers. On a whim, I added some Maxicrop Soluble Seaweed Powder to the plantings one year. Suddenly, we could grow gorgeous bell peppers.

Talking about growing peppers in a how-to on asparagus may seem out of place, but it illustrates something important. Obviously, our soil was missing something the peppers needed. Adding the Maxicrop evidently supplied an essential trace element for growing peppers.

Since that experience, I've spent a lot of bucks on Maxicrop, adding it to many plantings. Since you only prepare an asparagus bed once, adding something that would add trace elements just seemed to make sense to me. So our asparagus got some, even though it may not have needed it.

A good soil test before planting may be a bit expensive, but also could save you a lot of troubles.

Bugs and Diseases

We've been fortunate not to experience any severe insect or disease problems in our asparagus patches. I've included several links at the end of this article about disease and pest management.

Growing Asparagus from Seed

It definitely is possible to grow ones own asparagus plants from seed. I've done it twice when we simply couldn't afford to buy crowns. If I had to start another asparagus patch now, I'd probably just buy good roots. They're quicker and more hardy than tender, homegrown asparagus transplants.

Asparagus seed is a hard coated seed. In nature, the seed goes through a number of freezes and thaws, and possibly through a bird's digestive tract, to crack the hard outer coating of the seed.

To get asparagus seed to germinate well, it should be frozen for a time (weeks or months, not years). Using an emery board or metal file to slightly score the outer coating of the seed will allow moisture to reach the interior of the seed, triggering germination. Then the seed should be soaked in water for a day or so.

For our asparagus seed, I put the seed in four rows in a seed flat filled with sterile potting mix. I covered the seed with about a quarter to a half inch of sterile soil. I think just broadcasting the seed over a seed flat of sterile potting mix and covering it with soil would work just as well, as my rows got pretty messed up before I transplanted the asparagus.

I optimistically did the seeding in late winter, hoping to transplant in mid-summer. The seed took weeks and weeks to germinate. When the plants were finally up, it was way too late to put them into the ground and get established before winter. I overwintered the flat of asparagus plants under our plant lights before transplanting them into our asparagus bed the next spring.

Can One Save Asparagus Seed?

Female asparagus bearing seedIf your asparagus planting includes both male and female plants, some of the ferns will bear seed that should be as viable as any commercial seed. It probably will be just as hard to germinate as purchased seed, but stratification, scarification, and some patience should take care of that.

Asparagus seedOne can pick viable asparagus seed at the red to tan stage of seed development. Tan is better, but by that point the outer coverings begin to split and drop seed on the ground. Saved seed will need to dry for several weeks to permit easily removing the thin, outer hull of the seed.

Once one establishes a good asparagus patch, there's probably not much reason to save asparagus seed, as you should only have to start a patch one time. But saving seed may allow one to grow more crowns to fill in bare patches in a planting. I still have some saved asparagus seed in our freezer, just in case.

Purple Pee

Eating lots of asparagus can give ones urine a nasty odor and in extreme cases, turn it purplish. Since the harvest and gorging only lasts a few weeks, I don't think it does much damage to ones system. But like a bartender offering you a cup of coffee or to call a cab, such an occurrence is usually a good sign that it's time to back off on the spring asparagus feast.

After Adding All That Compost, Doesn't Your Asparagus Bed Fill Up?

A dear, departed gardening friend once asked me why my raised beds, including our asparagus, kept dropping in soil level each year. The answer, once I really thought about it, was that I was taking out lots of volume from our garden beds each year in produce, and stalks and roots to be composted. The harvested produce and garden trash removed was about like shoveling out an inch or so of soil each year. Adding compost, peat moss, and other organic matter every few years restores the previous soil levels in our garden plots and our asparagus patches.

Confession Time

Writing about starting an asparagus bed has proved to be a little more challenging than most of my how-to features. Since I haven't done the task in over ten years, I had to rely on my increasingly imperfect memory, Crockett, and web friends such as Paul Calback, who has started several asparagus beds in recent years.

Illustrations in this piece are limited, as I wasn't taking lots of garden photos in 2005 when I grew our transplants and put them in the ground in 2006. I was pretty well absorbed in those years with retiring from teaching and moving on to another job. Senior Gardening didn't open until July, 2008, although I was able to do a few backward posts to fill in 2008 and one for 2007 from what I'd published on my now inactive Educators' News site.

If I were to advise a new gardener starting a new garden, I'd suggest starting asparagus first. It is one of those crops that if started properly, will continue to produce for years to come. Of course, that's assuming that one likes asparagus. I hated it as a kid, but now eagerly look forward to our asparagus harvest each spring.

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last updated 1/16/2017
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