Just About Everything About Asparagus

learn everything about asparagus

Asparagus can be grown in almost every state of the U.S. It is even grown in areas of Hawaii that lack the frost to force the plants into dormancy. The following is  what you need to know to have a successful crop of this beloved perennial vegetable. We cover choosing the location to enjoying your harvest and everything in between.

Location! Location! Location!

When choosing the location for your asparagus bed, give it some careful thought. Being a perennial, your asparagus bed will most likely be around for at 15 years. Take a walk around your property at different times of the day, noting the sunny and shaded areas.

How much sun do asparagus need?

The recommended amount of sunlight to grow asparagus is 7 to 8 hours a day. Morning sunlight will be essential and 6 hours should be considered a minimum. If you live in an area of the country that has sweltering hot summers, such as Arizona, you might want to plant where your asparagus plants get shaded in the late afternoon.

It is also a good idea to look at the surrounding vegetation and landscaping. If you have young trees on your property, take into account how tall and wide those trees will be 15 years from now. Shrubs, bushes and even other vegetables, such as corn and tomatoes, can block the life-giving sun from your asparagus plants.

If your options are limited due to space or sunlight requirements, consider planting your asparagus as a border plant. You will only be harvesting the choicest spears, allowing the remainder to mature and develop the ferny headpiece that is critical to energizing the crowns for next year’s harvest. They are quite beautiful, turning golden in the fall, and can be the perfect airy-looking border for taller annuals or perennials.

Asparagus can also be planted in a raised bed, allowing for at least a 12-inch depth. Otherwise, the process is the same.

Prepping the Bed & Watering

Now that you’ve chosen where to plant your asparagus plants, it’s time to prepare the bed. Many gardeners will do this in the fall. They prep, adjust the pH and feed the bed in preparation for spring planting. But you can be as successful by doing a good job prepping your bed in the spring. We do recommend that you prepare the bed before ordering or buying your asparagus crowns, though. Our crowns are fresh, which means we harvest them shortly before you will be receiving them. And the quicker they are in the ground after you receive them, the better.

home soil testing kit for garden soil

Soil pH

The first order of business is to check the pH level of your soil. Asparagus plants prefer a soil pH right around 6.5 to 6.8. You can fudge a little on each side of those numbers, however, if your soil is too alkaline or too acidic, your asparagus plants will not grow as well. An inexpensive soil testing kit can determine the pH quickly, or you can take a soil sample to your local University Cooperative Extension office for testing. You also might check with your county’s agricultural services. Get a primer on the basics of soil pH to get an idea of what it is and how it impacts your garden.

Then, if you are starting from scratch, you will have to till the area that you will be planting. Are there grass and weeds? Loosen the soil with a shovel or with one pass of a tiller and get rid of as much of the grass and weeds as possible. The cleaner the bed to start, the less weeding and maintenance later on. You will also want to discard any rocks and then till the soil to at least 12 inches. Tilling with several passes should break up any large clumps. This ensures adequate aeration throughout the soil for your new asparagus plants. A well-prepared bed is a lovely thing. It will enable the roots of your asparagus plants to reach deep and establish well.

The final step, right before planting, is to dig a trench in which to plant your asparagus crowns. Make it 6 to 8 inches deep. If you will have more than one row, the recommended distance between rows is 4 feet. If pinched for space, 3 feet will work, but never plant the rows less than 3 feet apart. This leaves you room to walk between the rows for harvesting. It also allows adequate air circulation to dry the ferns after it rains. If you’re short on space, leave at least 8 inches between each plant. Though for best results you should plant them 12 inches apart.

How will you water?

This is also a good time to decide how you will water your asparagus plants. We recommend using a drip system or soaker hose. They’re both easy to install and use less water. This method also does not keep those ferny tops wet. Figuring out your water source in advance will save you from running to the store for hoses or sprinklers once you realize you need to water your freshly planted crop. We’ve all been there!

Choosing Your Asparagus

Most people will opt to grow asparagus from crowns, rather than seeds. When growing from seed, you will get a mixture of both male and female plants. Female plants tend to be a bit lankier. They don’t produce the the type of spears that are the most desirable and palatable. Female plants also produce seeds. Which creates a situation where your asparagus bed can become too crowded. Over-crowded asparagus is not happy asparagus! The ferny tops must be able to dry out. This requires adequate air circulation so that disease does not take hold. Male plants, on the other hand, produce more flavorful, stout spears. They also don’t create the extra work of weeding seedlings or the female plants out of your asparagus patch.

So, we recommend buying male asparagus crowns. The crowns are one year old plants that have been carefully harvested, along with their roots. They will appear dried out, but you can rest assured they are very much alive, just dormant.

Planting Your Asparagus

how to dig a trench to plant asparagus crownsWhether you prepare your bed in the fall or in the spring, you should not plant your asparagus plants until springtime. In fact, even if you till, feed and amend the soil in the fall, wait until the spring to dig the trenches. Otherwise you will end up re-digging the trenches before you plant.

Our asparagus crowns are grown and harvested fresh right before shipping. We harvest as soon as the ground is soft and dry. Which means that we do not ship our asparagus crowns until late spring. This gives you plenty of time to prepare your bed. Having everything in place for when your asparagus crowns arrive on your doorstep is smart gardening!

Right before planting, soak the crowns in water for a period of 15 to 20 minutes. This will give those roots a much needed drink and give them a bit of a jump-start on growing. Next lay the crowns in the trench at least 8 inches apart, though we recommend 12 inches for the best performance. Then gently cover the crowns with only 1 to 2 inches of soil and water.

Asparagus plants usually start sprouting when the soil temp reaches about 50°F. So you should be seeing those pretty green shoots within about 2-3 weeks of planting, depending upon where you live. Once you see the first shoots, cover them with a couple of inches of soil. Repeat the process until the trench is completely filled. 

Feeding and Over-Wintering Your Asparagus  

When you’re planting your asparagus crowns for the first time, we recommend that you sprinkle Hi-Yield Triple Super Phosphate in the trench right before planting. With an NPK value of 0-45-0, this soil amendment is pure phosphorous. Due to the way asparagus grows and its perennial nature, you do not want to feed with nitrogen. Nitrogen tends to spur quick plant growth. And when it comes to asparagus, slow, strong, healthy growth is best. Phosphorous, on the other hand, enables the transfer of energy throughout the entire plant. Which encourages the healthiest root growth. It is also essential to the process of photosynthesis. Your asparagus plants use the most phosphorous when the spears are first forming, and then again when they flower. So another moderate application of phosphorous is prudent when the harvest is complete and the ferny tops are appearing.

Caring for Asparagus in the Fall

The next time you will want to pay particular attention to your asparagus bed’s nutritional requirements is in the fall. Include it in jobs that will help to overwinter your asparagus plants. Some gardeners choose to leave the ferny tops throughout the winter and cut them back in the spring. We recommend cutting your asparagus plants back to the ground right after the first frost. The reason for this is that fungus can grow, even in the winter, when the ferny tops don’t get a chance to dry out. If you know you’ve got fungus on those tops, don’t compost them. The fungus can over-winter and grow on anything you use that compost on.

Once you’ve cut them back, cover the whole bed with 1 to 2 inches of well-composted manure or compost. Then sprinkle with Triple Phosphate or Bone Meal, which will leach down to the roots. It’ll provide that springtime pick-me-up as the soil warms and the spears start to grow again. This layer of compost will not only feed the plants but will help to insulate them.

In the spring, the spears will grow right through that healthy layer. This even holds true in places that don’t experience frost, like Hawaii. Except that once the ferny tops have been in place about 4 months, you will want to cut the asparagus plants back to the ground. Then treat them the same as if they were growing where winter occurs.

Harvesting Your Asparagus

“How do I harvest my asparagus?” is one of the most common questions we get.

Our crowns are already a year old when you receive them. This means that you may not have to wait another year to start harvesting. Though you should harvest prudently this first year to allow your asparagus bed the time to become well established and healthy. When you do harvest, you should only harvest the spears that are more than 3/8 inch in diameter (about the size of your little finger). This allows the smaller spears to develop that ferny top. Which will, in turn, provide energy back to the crown, resulting in a larger diameter spear the following year.

Limit your first two harvests to the first 2 to 3 weeks. This allows the asparagus crowns to continue to develop for the healthiest and longest living asparagus bed. From the third year on, you will most likely be harvesting every other day when the asparagus spears are between 4 and 8 inches tall. Usually for a period of 6 to 8 weeks, depending upon your geographical location.

The weather will also determine your harvest. Asparagus is a cool weather crop and one of the first vegetables to be ready for harvest. Don’t pick the asparagus spears if they are no longer tight at the top. Let those open to display the ferns that will perpetuate next year’s harvest. Nothing goes to waste!

How to Pick Asparagus

How to use an asparagus knife to cut spears When it comes to actually picking, many people will snap the asparagus spears at ground level. We suggest investing in an asparagus knife and to cut the spears 1 to 2 inches below the top of the soil. The reason for this is two-fold. First, there is less chance that you will damage the plant by pulling as you snap the spear. And second, that layer of soil helps to protect the crown after the spear is gone. It is also much quicker and easier to harvest with an asparagus knife and it results in a longer spear..

Also, do not believe the myth that larger asparagus spears are not as tender. What IS true is that as the spear grows both in height and in diameter, the part below ground and sometimes about an inch above the ground will get a little tougher. Use a paring knife to cut off the tough part, saving the tenderest part of the spear. Compost the tough bits or feed it to the chickens!

Enjoying and Preserving Your Harvest

In our opinion, grilled asaparagus is the best way to eat it! You can grill it on foil, but having a pan with close-set holes to place over your grill will result in the best flavor. Spray the spears with a bit of olive oil and season with garlic, sea salt and pepper and then grill to perfection! Of course, that’s not the only way to enjoy asparagus. What’s your favorite asparagus recipe? Share it here in the comments or on our facebook page.

Preserving asparagus: canning, pickling, freezing or drying.

Drying Asparagus

Dry asparagus in a food dehydrator and then add it to soups and stews throughout the year. First, wash the spears thoroughly and halve the largest spears. Then steam them 4 to 5 minutes or blanch in water for 3.5 to 4.5 minutes. Finally, dry 4 to 6 hours in a dehydrator or oven. Of course, the drying time will depend on the initial moisture content of the asparagus tips and the type of dehydrator you’re using.

A conventional oven can take twice as long. A convection oven with the fan going should take about the same length of time as a dehydrator. You will want to use perforated trays and allow 3 inches of clearance between the top and the bottom of the oven. Cheesecloth stretched over baking pans or over a frame is perfect. It won’t react with the asparagus and provides exceptional air circulation. Set your oven thermostat at 140° to 150° and prop the door open a little to allow moisture to escape. The asparagus tips are dry when they are leathery looking and brittle. Store serving-size portions in airtight containers in a cool place. Then break them out to use in casseroles, stews and soups.

pickling asparagus to canPickling Asparagus

One of the most popular ways to preserve asparagus! Due to its low acidity, asparagus requires a pressure canner for canning. But can be processed with a water bath canner when pickling.

Freezing Asparagus

A simple way to keep asparagus as close to fresh as possible. Blanch small spears for no longer than two minutes and larger spears not more than three. Then put in freezer bags or containers, removing as much of the air as possible. If you vacuum seal, you can skip the blanching process. This keeps the texture fresh and the spears are still that gorgeous, just-picked green.

Canning Asparagus

The best long-term storage solution! Asparagus has low acidity, so you’ll need a pressure canner. You can either cut the spears to fit quart jars, or cut in smaller peices, like green beans. Be sure to use a spatula to squeeze the air bubbles out of the jars before applying the lids and then process at 10 lbs. of pressure for 25 minutes.

We hope this answers all your questions about how to start, establish and enjoy your own long-lived asparagus patch. In our opinion, nothing, absolutely nothing, beats the flavor of fresh, home-grown asparagus tips. The longer the spear is off the crown, the more the flavor (and even the texture) deteriorate. So eat it fresh or process it quickly. Store-bought asparagus tips, whether fresh, canned, frozen or dried, will never compare.

Enjoy!

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25 Comments

  • Reply
    Jim Fuquay
    October 19, 2012 at 10:34 am

    Thanks for the article. It was full of good information. I just planted my asparagus garden this year and was looking for next steps and things to avoid, which this article provided. 🙂

  • Reply
    karen
    May 4, 2013 at 9:49 am

    can u plant the seeds off a wild plant?

    • Reply
      jstutzman
      May 9, 2013 at 12:24 pm

      Karen, you certainly can plant the seeds off of wild asparagus.

  • Reply
    Marla
    November 21, 2014 at 11:34 am

    Can asparagus be grown in a container, such as a hydroponix type box?

    • Reply
      jstutzman
      December 30, 2014 at 11:16 am

      Hello Marla. Unfortunately asparagus is a deep-rooted perennial that does not work for hydroponic gardening.

  • Reply
    JarrettK
    December 28, 2014 at 10:29 am

    I planted 1 yr crowns 2 years ago. We have now decided to move and I’d like to take our crowns with us. I already dug up the small crowns (in December) and hope to store them over the winter so I can replant them in early spring. We may be moving over the winter so I may not have a chance to dig them up in the spring. We had some recent warm weather which thawed the ground so I took the opportunity to dig up the crowns. Is storing the crowns a viable option? And if so, what is the best way to store them?

    • Reply
      jstutzman
      December 30, 2014 at 11:07 am

      Hello Jarrett. Yes asparagus roots can be stored, although it is not recommend. With that being said, you should keep them in a dark area that stays between 35-40 degrees Fahrenheit. It is also important to not let them dry out. Good luck.

  • Reply
    theresa ammirati
    June 9, 2015 at 6:35 pm

    my asparagus has developed ferns at the top. can i still harvest and eat it or must I wait till next year?

    • Reply
      jstutzman
      June 10, 2015 at 9:53 am

      Theresa, once the asparagus spears start opening up, you must stop harvesting. The ferns will grow 5-6 feet tall over the summer. They can be cut back to the ground level once they turn brown. Enjoy your plants! GHS

  • Reply
    Betty
    May 15, 2016 at 10:09 pm

    I actually have 2 questions. Can they be grown in raised beds as long as they are deep enough (what would be proper dimensions) and is growing white asparagus the same except as the plants emerge you just hill up above the rows? Thanks for you consideration. Betty

    • Reply
      jstutzman
      May 17, 2016 at 1:48 pm

      Betty, asparagus can be grown in a raised bed as long as there is no bottom on it. All asparagus is the same when it comes to growing conditions. Good luck. GHS

  • Reply
    Shane
    May 26, 2016 at 1:48 am

    Hi. Thanks for the site. I did a pretty stupid thing last week when planting my asparagus. I decided on soaking the crowns in compost tea before planting and, inadvertently, left some of them soaking for three+ hours (!!). I still planted them…but I’m concerned that I may have “drowned” them in leaving them in the “tea” for so long. Is that possible??

    • Reply
      jstutzman
      June 7, 2016 at 11:11 am

      Shane, I don’t think this will be too much. Your asparagus should grow just fine. Happy gardening. Joe

  • Reply
    Ed
    June 15, 2016 at 12:09 pm

    I had great luck with my asparagus for 4 years, this year it’s only coming up at one end of the 8 foot bed, and the rest of the bed is not coming up. why do you think that is

    • Reply
      jstutzman
      June 16, 2016 at 8:17 am

      Ed, that’s a good question. Unfortunately there might not be a good answer. Can you tell me how deep the soil in the raised bed is? Also, what hardiness zone are you in? Joe

  • Reply
    Jodi torkelson
    August 3, 2016 at 9:34 pm

    Our asparagus was ripped from the ground due to road work on August 3rd. The roots are still intact and some of the plants have roots attached. Any way to store the plants with roots still attached through the winter and plant in spring?

    • Reply
      jstutzman
      August 5, 2016 at 2:34 pm

      Jodi, if you keep them in a dark place that stays round 38 degrees, they will keep. Otherwise you could plant them somewhere else now and dig them back up later in hopes they would survive. Good luck, Joe

  • Reply
    Lar
    October 19, 2016 at 12:20 am

    I have yet to grow asparagus my question is do you get multiple harvests or just one? Secondly I will be moving to central Georgia with the red clay soil besides compost what should add to it? Thank you in advance

    • Reply
      jstutzman
      October 19, 2016 at 1:19 pm

      Lar, congrats on your upcoming move! Asparagus roots send up what’s called “spears” in the early spring of each year. When the spears are at least one-half inch in thickness, you can harvest it. Most folks wait till its about 8 inches above the ground, then they use a knife and cut if off even with the soil. That same spear will grow out again and again each time you cut it off. However within a couple of weeks, the spears will start getting hard. When that happens its time to let them just grow, no more cutting. Depending on the conditions in your area the harvest could take place over 3-4 weeks. The best thing you can add to any soil is manure. If its available, horse manure is the best. For really poor soil, dig trenches about 8 inches deep, fill it with manure, then cover it back up. Happy gardening, Joe

  • Reply
    Diana
    June 27, 2017 at 11:27 pm

    Thanks for all the great info. One question though. My asparagus row is 2 years old from crowns, and is doing well. (I’m in Manitoba, Canada). Plenty of new seedlings are sprouting below and around the plants and I’m not sure if I should leave them or pluck them out or transplant them somewhere else. My concern is that if I leave them all, the area will become too crowded. Is the overall, long term survival of my patch dependent on these seedlings?

    • Reply
      jstutzman
      August 10, 2017 at 7:42 am

      Diana, it sounds like your variety is producing seeds, which will make them spread. It would not be worth your time to transplant them. Just snip the ones as they come up, it might have to be done weekly. Joe

  • Reply
    Paula
    March 15, 2020 at 5:20 pm

    Hi there!
    Great information. Just wondering if you can pinch back asparagus seedlings when starting from seed to bush out the plant or if that will harm the seedling? Thanks so much!

    • Reply
      GrowJoy Plants
      October 13, 2020 at 3:11 pm

      Paula, you should never pinch asparagus. It needs to fully mature each year to fully develop. It should only be cut back after a frost. Hope you had a great harvest this year.

  • Reply
    Ruth Offord
    October 13, 2020 at 10:51 pm

    Hello, I planted my asparagus crowns a year ago in a waist height raised bed.
    The soil level sunk about a foot, so I topped up my bed with an extra 8 inches or so of soil.
    It has continued to sink and I’m worried if I top it up again the plants will be way to deep down.
    Should I wait till winter and dig them out and plant them nearer the surface, or will they work their own way up?
    Many thanks
    Regards Ruth

    • Reply
      GrowJoy Plants
      October 15, 2020 at 1:42 pm

      Ruth, they will need to be dug up after the first freeze. First, cut the tops back to the soil level. Then dig them up. Refill the box with soil, then plant them 8 inches deep. Hope this helps – happy growing!

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