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How to Protect Asparagus Plants from Winter

Asparagus seeds
Avoid letting asparagus set seeds

Protect perennial asparagus plants from cold temperature damage by mulching the asparagus bed with compost, aged manure, or straw before freezing weather or snow arrives.

Asparagus crowns can produce tasty spears for 20 years or longer if given the right care and nutrients.

The ferny stalks and branching growth of asparagus plants capture energy through photosynthesis during the growing season strengthening asparagus crowns (the collection of fleshy roots just below the soil surface) for spear production the following year.

Leave asparagus stems on plants as long as they remain green—well into autumn. When stalks turn brown and brittle cut them off at ground level and top dress the bed with compost or manure. (Place cut stalks and ferns in the trash—not in the compost pile; asparagus-beetle eggs can overwinter in cut stalks.)

Again, cutting stalks back too soon means sacrificing photosynthesis and will mean less spear production next year. The exception: cut down female asparagus plants before they set seed (red berries); seed production diverts energy from crowns and lowers future yield. (Picking off berries is a solution, but highly time consuming. Growing only male plants may be the best course—as well as the source of thicker spears.)

Where heavy snow covers asparagus beds in the winter let stalks turn brown and fall across the planting bed to form their own mulch to protect plant crowns. Then add 6-inches of straw, pine needles, or well-rotted or chopped leaves to the top of fallen stalks to give crowns extra protection from freezing temperatures.

A planting bed of well-drained garden loam is the best home for asparagus plants. Adding organic matter—well-aged compost or well-aged manure and a layer of straw or chopped leaves—to the asparagus bed each autumn will ensure crowns and plants have the nutrients they need to produce ample spears for years and years.

Autumn is also a good time to check the soil pH in asparagus beds. Asparagus plants prefer a sweet soil—a pH of at least 7.0. Add lime to raise the pH or sulfur to lower it.

 

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59 Comments

  1. Hi! I have a really stupid question. My husband and I just put up a cheap and simple greenhouse over my raised garden with pvc pipe and clear tarp. He insisted on closing of the whole thing (stapling the tarp down on the ends) for the winter. I am worried because my asparagus plants are in there and they are not going to get any water. I hate to tear open the ends of the greenhouse but they need watered even over the winter right????
    Thanks for any advice!! Tracy

    • It would be best to allow some access to your greenhouse through the winter. You can do this by not sealing one end of the greenhouse or tunnel, instead clip it shut. Your plants may need some water, and, as well, you will want to allow for some ventilation should you have a warm spell and temperatures inside the greenhouse start to climb.

  2. Can I plant asparagus now in North Louisiana? I bought crowns at a Walmart 2 months ago. We have a bed with appropriate rows and spacing We have some crowns that we had in s container got years and now I have 2 rows of older plants and we are lettin them fern. Can we harvest them since they are older transplants.

    • Yes, you should go ahead and put the asparagus crowns in the ground–before they dry out and lose their vitality. Keep the soil evenly moist once you put the crowns in the ground. Your older plants should be at the harvestable stage at about 3 years of age.

  3. I am completely renovating my garden and stating new next spring but I don’t want to lose my asparagus. Can I overwinter them in pots? If so, why would be the best place to store them?

    • If possible, the best time to transplant or relocate asparagus plants is late winter or early spring while the plants are dormant. If you must move them sooner, take up as much of the plant and root as you can and set it outdoors where it does not get full afternoon son–to avoid too much transplant shock. Overwinter them close to their current home.

    • If the foliage has died back for the winter, then go ahead and bring your asparagus indoors. If not, let it continue to store energy for production of new spears next spring–until the top dies back.

    • Yes if the manure is well aged. It would also benefit your growing bed to add aged compost. The winter rains and late snow melt will carry the nutrients deep into the soil before the asparagus emerge in spring.

  4. This past asparagus season I did not have much of an asparagus yield. Everything looked okay…a lot of greens…just not enough asparagus. My soil may have been depleted of nutrients. I just cut down the greens this week. I have some bagged soil–a combination of compost/moss…and something else I can’t think of…and some leaves. Would this be enough to put on top for the winter or should I add some other nutrients. This asparagus plot is about 10 years old and I’m in Western PA. Thanks!

    • It’s best to feed your asparagus bed every year–about this time. Put down 2 inches of aged compost or a commercial organic planting mix.
      If you want to give the bed an extra boost, sprinkle 5-10-10 organic fertilizer over the bed before you put down the compost. If it has already snowed where you are, put down the aged compost or planting mix as soon as the snow melts. Let winter snow and rain work the amendment into the soil–no need for you to turn it under.

  5. My asparagus plants are growing over 10-12 feet tall. Should I cut them back or just let them grow for better production? I live in North. Louisiana

    • In mild winter regions, cut down ferny asparagus top growth after it has turned brown in late fall. In cold winter regions leave top growth to provide winter protection. Top growth will help plants store energy for new production; once plants flower and set red berries, plants will begin to draw on stored energy.

  6. Winters here reach -30c(-22 Fahrenheit), is it still possible to winterize my first year asparagus outside,even with good bedding? Would it be a good idea to bring them inside for the winter?

    • Once you trim back the browning fronds, you can sprinkle aged compost and aged manure over the bed to feed the roots for next season. Once the first freeze comes, heap more compost over the bed and then a layer of straw to insulate the roots from freezing. If the soil freezes where you live you can lift the roots and store them in peat moss or loose soil through the winter and replant them next spring.

  7. I didn’t cut my asparagus plants down last winter. I let them fall over and lay over the top. Now that it’s spring, how short should I cut them before adding new mulch and compost?

    • Cut asparagus top growth down to soil level. You can then sprinkle balanced organic fertilizers such as 10-10-10 across the bed before you add new mulch and compost.

  8. I started my asparagus seeds 10 weeks before Frost ended this year in pots I’ve transplanted 3 *. And then I wasn’t able to get them planted in the ground. Are they going to be okay in there pots till until spring. They’re big bushy and green still. And shall I bring him in the garage four winner where in zone 6A.

    • Because the asparagus is still in pots it may be a bit late to set them in the garden and expect the roots to establish themselves before winter cold hits. You could transplant them and protect the top growth with floating row covers giving the roots a couple of months to get established. Perhaps a better strategy is to bring them into the garage when the tops die back and then transplant them into the garden in spring.

  9. I started a new bed this spring and was able to enjoy a couple of snacks from it. There are a couple of thin spots where they didn’t take. I’m in memphis tn, when would be the best time to add a few crowns to fill in?

    • Plant asparagus 4 to 6 weeks before your area’s average last frost date in spring. Asparagus prefers climates where winters are cold enough to freeze the top few inches of soil and provide it with the necessary period of dormancy. In mild winter regions, some folks will dump a bucket of ice over the roots of each plant in winter to simulate the freeze.

  10. This is my first year with Asparagus plants they are looking good , but I was wondering what do I need to do to get them ready for the winter.
    I live in Mississippi, and then for the spring time also.
    Ruth

    • Remove the ferny tops of the asparagus plant in late fall at the first sign of frost. After the ferny tops are removed, apply 6 to 8 inches of aged manure or compost over the bed; this will act as a winter blanket and add nutrients to the soil for renewed spring growth. In spring, you will simply wait for new spear growth. If your plants were just started from crowns or seedlings this year they do not harvest the spears for the first two full seasons. Give the plants two full years to establish their roots. The first harvest will come the third year after planting–then harvest for just two weeks. The next season harvest for four weeks.

    • Hold off cutting back the asparagus tops until they have been hit by a couple of frosts or a freeze. While they are still green they are storing energy for next springs spears.

    • Yes, chop the alfalfa into bits and spread it across the asparagus bed as a winter mulch (much like you would do with fallen autumn leaves). If you leave the alfalfa unchopped, you will want to pull it back from the asparagus bed next spring. Chopped alfalfa will decompose more quickly adding nutrients to the soil and feed beneficial soil microorganisms. It will also enhance soil composition.

  11. I live in North central CT, my asparagus bed is going the 4th year. I have spaces between sprouts. How can I fill the the gaps? Should I use sets or seeds and how deep should it be planted.

    • The quickest way to fill in the spaces in your asparagus bed would be planting two- or three-year-old crowns. Crowns will likely be available again early next spring; check with the nearby garden center. Choose crowns that have plump fleshy roots; avoid crowns that look dry. When the soil is workable in spring amend each planting hole with aged compost or commercial organic planting mix and sprinkle bone meal at the bottom of the hole. Soak the crowns in compost tea or a starter solution for a few hours before planting; moisten the planting hole as well. Set the crowns about 6 inches deep (8 inches if the soil is sandy). Plant the crowns 2 to 4 weeks before the last average frost date.

  12. I live in the suburbs of Detroit Mi., my asparagus plants started coming up in my raised beds then we had some freezing weather, it looks like my spears got hit by the freeze. They are whitish around the soil level and they quit growing feels soft, what should I do with those spears. The weather has changed now started to warm up and I do have some new spears coming up but I don’t know what to do with the old ones. Any suggestions are helpful

    • The white at the tips of the asparagus is a sign that the plant cells froze, and were essentially destroyed. You can trim away the white and eat whatever part of the spear remained green. Once spears break the soil and when a frost or freeze is forecast, cover the plants with row covers to protect them.

  13. I live in Minnesota and am thinking about starting asparagus in a large container. Do I need to worry about being able to insulate in the winter? Air temp can vary down to -20. The container I am using is too large to bring into a garage for the winter. Will this work?

    • Yes, insulation will likely be needed to keep the soil and roots from freezing. You could consider placing loose straw or bales of hay around the container or wrapping the container with styrofoam or another insulating material.

  14. I live in Central new York, planted my one year-old asparagus roots. It’s been a cold spring we’ve had temperatures drop Below freezing – Will my Asparagus routes going to survive these low temperatures?

    • Asparagus roots are tough. They will likely survive freezing weather as long as the ground has not frozen. Cover the planting bed with a floating row cover to straw until temperatures are warmer.

  15. Its my first year growing asparagus in a pot. I have (too) many plants growing in a big pot and I’d like to transplant them to a larger garden bed area. Can I transplant them in the fall? I’m in RI.

    • Yes, you might want to transplant in late summer and give the roots a chance to settle before cold weather; the roots will grow as long as the soil remains warm–until about mid-autumn; when winter comes mulch with a thick layer of straw or chopped leaves to protect the crowns from winter cold.

  16. My 1st year asparagus is green fern, 2-3 ft tall. Denver CO zone 5. Should i cut the green back when 1st frost hits or when they turn brown? Or leave ferns to fall over before putting straw on beds to winterize? Also do i put straw on 1st year strawberries?

    • As long as the ferns are green, they are working to store energy for next year’s crop; allow them to die back naturally. Cut them back when brown before first snow. Add straw once tops are cut back. Same with strawberries; no need to mulch with straw while ground is still warm. Cover before first hard freeze.

  17. I planted asparagus seed this year. It is growing in a pot but I never did plant it in the garden. Can I bring in those plants and keep them alive until the spring when I can plant them? Or should I let them die back and then hope they will start again in the spring so I can plant them. Or is there no hope of saving them for the spring so I should just get rid of them.

    • You can bring them in and then set them in the garden in spring. If they are still green, you can plant them in the garden now; if your winter is not bitter cold, they should survive and begin new growth in spring.

  18. We have had an early cold spell here in Minnesota. Freezing with the temps in the lower twenties. I was waiting for the asparagus to turn brown to remove for winter. Some stalks are brown and other green. Should I remove the snow and cut it down or wait for a thaw and browning to occur?

      • I LIVE IN SOUTHERN CA. THIS IS MY SECOND YEAR OF HROWING MY ASPERAGUS PLANTS. THE ARE BEGINNING TO TURN YELLOW AND THE NIGHT TEMS ARE DIPPING DOWN TO 50 TO 38 DEGREES. DO I BRING THEM INTO THE GARAGE OR MY HOUSE OR LET THEM STAY OUTSIDE UNTILL THEY COMPLETLY TURN YELLOW? ONE HAD TURNED YELLOW AT RHE TOP,BUT STILL GREEN AT THE BOTTOM. YESTERDAY THE WIND BLEW THE TOP YELLOW PART OFF, BUT THE GREEN PART REMAINS (IT IS PLANTED IN THE GROUND, THE OTHER TWO ARE IN TWO LARGE POTS) THIS IS ALL NEW TO ME! SIGH….

        • Asparagus will remain in the garden for up to 15 years. Ther roots and crowns can survive harsh winters–which you will not have in Southern California. If temperatures dip to below freezing where you live you can cover the asparagus bed with straw, but first allow the green ferny tops to turn yellow and brown and die back on their own. You can cut them down in January.

  19. I live just North of Dallas and my asparagus is doing great. My question is should I pick the red “berries ” off of my female plants or let them drop naturally? Thanks for your advice.

    Dorothy

    • If the asparagus is open-pollinated (not a hybrid variety) you can allow the berries to mature and drop naturally; you can then collect them and start new plants from seed. The dropped berries you miss may start new plants as well. If the plants are hybrid varieties or you want to avoid dropped berries, you can remove the berries; that will allow the plant to put more energy into the roots and future development of new shoots. Berry development takes energy and nutrients away from future shoot developments–the reason you are growing asparagus to begin with.

    • You can induce dormancy by not watering; this should cause the ferny tops to turn brown. If the tops remain green until mid-winter, you can cut them back then; they will grow new ferny tops beginning in spring. The roots need a rest period and they won’t get rest if the green tops remain in place.

  20. Hi
    I live jn North Wales.
    I planted a few asparagus plants three years ago last summer, in a sheltered area.
    I watered them during spring, often, but I don’t know whether it was enough, as the spires did not emerge until later than expected. But it was also dryer than usual, actually hot for us!
    I covered mine in late autumn with fallen leaves. Last year I did not remove them in the spring, as I expected them to rot and add nutrients to the soil. Perhaps it was not a good idea?
    Should they be replaced with well rotted compost, as I have no access to manure?

    • Aged compost is the best organic amendment for the garden with both major and minor nutrients. If you use leaves as a mulch, be sure to pull them back from the plants when sprouts begin to emerge in spring. If the weather is dry, it is important to keep the soil surrounding young asparagus moist; the crowns can dry out, shrivel, and die if the soil goes dry.

  21. I live in eastern Long Island New York zone 7b. I first planted my asparagus last spring. I let the ferns grow out all summer and fall without mulch for the winter. We had a few snow storms during the winter with the ferns still up. Now Its just about spring and I cut the ferns down to soil level and covered with compost. I hope this all makes sense to you. My question is, do you think I’ll be ok and what are the signs to look for indicating things are or might go awry? Thank you, I appreciate all the info you give.

    • Take the soil temperature with a soil thermometer; as the soil warms near 50F, you should seed new sprouts emerge. If you don’t see sprouts emerge as the soil warms, it is possible freezing weather may have injured or killed the crowns. However, it is likely you will see new growth. Next autumn, compost the bed ahead of cold weather to protect it from freezing temperatiures.

  22. I moved into a house that has a 30-ft asparagus patch in the backyard. It is overgrown with weeds and full of straw. If I harvest all of the asparagus that is up, can I mow the grass down and remove the straw with a rake? Then I can pull the rest of the weeds and grass out. Will this hurt my asparagus plants? Will they grow back okay? Or do you have a better suggestion?

    • If the asparagus spears are as round as your index finger, you can harvest them. If they are thinner, it would be best to let them grow their ferny tops and store energy for next year’s crop. If it’s possible to weed and pull up the mulch around the asparagus and allow it to grow on that would be the best strategy.

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