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Asparagus Growing and Care Calendar

Organic farming asparagus in black soil

Asparagus is among the earliest and tastiest crops each year. Perennial asparagus beds can produce spears for decades and decades with proper care throughout the years.

Plant asparagus where there is plenty of sun in the spring and the soil is rich in organic matter and well-drained. As a guide, you will need about 20 to 40 crowns for each person; 20 for the spring harvest, and more for a second or third harvest later in the season.

Keeping the asparagus patch productive will require a few simple tasks each season.

Here is a season-by-season guide for asparagus growing and care:

Spring asparagus harvest
Asparagus is ready for harvest in mid to late spring

Spring Asparagus Garden

Asparagus spears will be ready for harvest shortly after the soil temperature reaches 50°F (10°C) in early spring—that’s when spears will begin to emerge. Two weeks before spears begin breaking through the soil, pull the winter mulch back and cultivate the asparagus patch lightly loosening the soil and uprooting weeds.

Begin the harvest when spears are 6 to 8 inches (15-20cm) long; that’s when they are most tender. Don’t let spears grow taller; they will become tough. Harvest spears daily during the harvest period; cut or snap each spear off just below the soil surface.

Harvest will last 2 to 10 weeks depending upon the age of the plants. The first harvest year pick spears for 2 weeks; this will allow roots to become established and grow strong. Each year after, increase the spear harvest by a week.

Once spears have started to grow tall, weed the growing bed once more than place a 4 to 6-inch (10-15cm) layer of straw or hay or dried grass around plants for the remainder of the harvest and growing season. Mulching after spears have emerged will keep weeds down and preserve soil moisture through the warm time of the year. Weeds that grow up through the mulch can be easily pulled by hand. An alternative is to sow annual ryegrass around asparagus plants in spring. Ryegrass will crowd out small weeds and will die off in winter.

Asparagus crown planted
Asparagus crowns can be planted in spring; these will be ready for harvest in 2 to 3 years.

Late Spring Asparagus Garden

Plant for future asparagus harvests in late spring. Sow asparagus seed 1½ inches (3.8cm) deep and 2 inches (5cm) apart in loose, well-drained soil. Sow seed when the soil temperature is between 70 and 75°F (21-24°C). Seeds should emerge in 10 to 20 days. Keep the soil moist and control weeds. Later, thin plants to 12 inches apart.

Transplant asparagus crowns (one-year-old rhizomes) in spring about the same time you transplant out tomato plants. Set crowns at the bottom of a trench 10 to 12 inches (25-30cm) deep and cover with 2 to 3 inches (5-7.6cm)  of soil. Set crowns 12 inches (30cm) apart. As plants begin to grow cover the new growth with 2 inches of soil every few weeks until the trench is filled. When spears shoot up the first year, let them leaf out and grow on.

After harvest in spring, feed each plant an organic fertilizer to support top growth through the summer; summer growth will determine how good the following year’s spears will be. Aged compost and well-rotted manure will feed asparagus beds. (Add nutrients in spring before spears emerge and again after the last harvest.) A rich asparagus fertilizer is three parts greensand, two parts cottonseed meal, one part dried blood, and one part bone meal applied at the rate of 2 pounds (.9kg) per 50 square feet (4.6 sq. meters) of the bed.

During the warm season, keep weeds down with a thick layer of straw, hay, or dried grass clippings—fresh grass clippings contain too much moisture to use as a mulch without first drying; they can become slimy and moldy if applied freshly cut. Weeds will compete with asparagus plants for nutrients and diminish both yield and spear size.

summer asparagus
Summer asparagus fern growth allows roots to store energy; stakes and garden twine keep plants upright.

Summer Asparagus Garden

After harvest, let the plant’s fernlike foliage grow tall. Summer growth allows asparagus roots to grow large and store energy for the following year’s spears. Stakes and string will keep plants upright. In breezy areas, plant rows parallel to the prevailing wind so that plants can support each other. Crowns grow upwards about 1 inch each year, so spreading compost across the planting bed or along rows in summer will both feed plants and raise the soil surface.

To get a second or more harvests each year, plant twice the number of plants or more needed for each person (40 rather than 20) then harvest only half of the bed in spring and let the other half grow on. In early summer, cut down the top growth in the half of the bed that was not harvested. This section will send up new spears in a few weeks that can be cut in late summer or early fall for a second harvest. If the growing bed is large enough, you can divide the bed into sections and use this method for a new 2-month harvest every 8 weeks, multiple asparagus harvests each year.

Asparagus in autumn
Asparagus plants after autumn with hoar frost

Late Fall and Winter Asparagus Garden

In mild winter regions, cut down ferny top growth after it has turned brown in late fall or winter. (Even in autumn, asparagus tops may look dead but are still storing energy for spear production the next spring.) In cold winter regions, don’t cut back top growth; let it provide extra protection for roots from freezing temperatures.

(You can allow asparagus berries to mature and drop each fall. In spring, thin out new plants started from dropped berries; allow some new plants to establish and replace older plants.)

Where you cut back top growth, mound 3 or 4 inches (7.6-10cm) of soil over crowns, or add 3 to 4 inches of aged manure and compost across the bed to protect roots from cold temperatures. An alternative is to mulch the bed with 8 inches (20cm) of loose straw or hay and add phosphorus and potassium-rich cottonseed meal and wood ashes across the mulch. Deep mulching is important in cold regions to protect asparagus from tip-kill in spring and feeding is important for future spear production. A decline in spears is commonly the result of a lack of nutrients.

Adding 4 to 6 inches (10-15cm) of aged compost over planting beds and asparagus crowns each year effectively increases the depth of the crowns which in turn increases spear size and tenderness the following spring. When spears become spindly, crowns may have grown too close together and older plants should be thinned out.

Leave winter mulch in place until the danger of a freeze has passed in late winter or early spring, then pull the mulch back and ready the bed for the spring harvest.

More tips at How to Grow Asparagus.

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60 Comments

  1. An elderly man told my husband that the asparagus needed salt,. How would that help, he said it would kill the grass and weeds but not the asparagus. He said it makes the wealthy.. Is that correct

    • Salt will keep a planting bed almost weed free; so will weeding and mulching with a thick layer of compost or a layer of newspapers covered with straw. Salt will kill weeds in an asparagus bed and won’t harm the asparagus plants which can tolerate a saline soil. But the salt can also break up and damage the soil structure in your planting bed. If you want to try the salt, spread it lightly no more than 1 pound of rock salt (NaCl) per square foot or 2.5 lb. per 100′ row either before spears appear or about mid summer. Salt may help asparagus resist crown and root rot diseases caused by Fusarium fungi. Don’t use iodized table salt or rock salt made of calcium chloride (CaCl).

    • Cover a small part of the asparagus bed with mushroom compost and then monitor the plants in that area to see how they respond. Mushroom compost can–but no always–contain high levels of soluble salts and other nutrients that can be a bit too rich for germinating seeds and young plants. An established asparagus bed will likely do just fine, but treat only a portion to see if there is any adverse effect.

  2. I recently bought a container-started asparagus that is apparently loving life–after we got it home it grew multiple slender stalks very quickly. The tallest one is easily four feet tall and growing. It’s not even pencil diameter though.

    This being a new-ish plant I don’t want to cut off the stalk too early if I should be leaving it to grow, but I also don’t want to let it get so big that it snaps under its own weight. All the advice I can find about pruning asparagus seems to be related to fall and winterizing so I’m still at a loss. Should I be trimming these back or staking them up and just letting them do their thing this year?

    Thanks!

    • Let the asparagus grow until the first freeze, then trim it back to the ground. In the first couple of years, do not harvest. Allow the plant to grow naturally. During this time the plant’s ferny leaves are helping the roots establish themselves, store energy, and grow strong. In the plant’s third year, it will be strong enough to be harvested and to grow back each season. You don’t need to stake the stalks.

    • If your asparagus bed is still producing the number of spears you need and the spears are of sufficient size then there is no need to dig up and replant the bed. If you have noticed that the yield is declining and the spears are growing thinner, then it may be time to replant. If you have room, start a new asparagus bed in another location; it will be ready for production in 2 or 3 years and by then your current bed may be ready to retire. An asparagus bed can produce for more than 20 years as long as you feed the soil on a regular basis–adding plenty of aged compost or a good commercial planting mix.

  3. I was physically unable to prepare my bed for winter this last winter. I am in a realitivly mild area with just a few freezes. So, with no mulch put down, I have a bed of thick weeds and crabgrass! Hand weeding will kill me! It’s a big bed and these roots go deep! Can I spray the bed before the asparagus starts coming up? Will the asparagus, still underground, be ok??

    • Spraying asparagus beds for weeds with an herbicide is not the best course. Trimming the weeds down to an inch or so above the bed with a line trimmer would be an alternative to hand weeding. Annual weeds will naturally die and disappear if not allowed to flower and drop seed. Always cut weed tops before they flower and drop seed. Perennial weeds are a much more difficult problem since they store food and energy in their roots. You will want to pull perennial weeds by hand or treat them individually with an organic herbicide.

  4. Our patch is over 71 years old and some of the dirt has washed away and I feel it needs more dirt on top. When is the best time to add dirt? We have put salt on it for years is this bad or good?

    • Wow! 71 years. That must be a record! Add aged compost or an organic planting mix across the top of the planting bed any time during the year. Spring after harvest is a good time to spread compost or planting mix around asparagus before they grow tall. Another good time is at the end of the season if you cut plants back before winter. Aged compost and organic planting mix are excellent adds to asparagus beds.

    • my grandparents had a bed that had to be 50+ years old. I just started mine this year at my home. Looking forward to getting asparagus in a couple of years.

  5. I put in raised beds two years ago. The spears are just coming up for this season but the dirt has settled dramatically. I have 6″ of space that used to be soil. Can I still add soil, as I did when they were first planted? Thank you.

    • Yes. The soil in raised beds will settle over the course of the season and as plants draw nutrients from the soil. Add 2 to 4 inches of commercial organic planting mix or loamy aged compost to your raised beds twice a year. Lightly mix the new soil in with the old soil. The only time you will need to completely replace all of the soil in a raised bed is if or when you find a soil-borne disease that affects your plants.

  6. I planted 2-year crowns into a raised bed last year, let them flower, then I trimmed them down for the winter. They have shooted this spring and begun to flower. Should I repeat and NOT harvest or harvest this year?

    • Asparagus crowns should grow to full strength in 3 to 4 years. Since your plants are in their third-year harvest a few spears this year but let the other grow on; their ferny stops will help roots store more energy for a full harvest next year. Asparagus plants can produce for 15 years or more so you have many full harvests ahead.

    • Asparagus crowns may take several weeks to establish themselves below ground. If the crowns (roots) were healthy and plump (not dry) when you planted them then it will be a matter of time before the roots become established and then can push new growth to the surface. Keep your soil evenly moist, not wet and never dry. If the weather is hot where you are, you may want to place a floating row over the planting bed to protect the soil and crown from solar heat.

  7. I wish to divide my mature crowns to enlarge my bed by another row or two. I note that you suggest doing this in early Spring, It will be difficult to do this before new sprouts emerge as they do this very soon after the frost leaves the ground, Can the crowns be dug up and divided while the new shoots are emerging or must I try to get this done in the short period before the sprouts emerge?

    • Asparagus crown division can be done as soon as the soil can be worked in spring. If the soil does not freeze where you live, you can divide crowns in winter. The division will stress the crown so it’s best to do it when the plant is dormant before it sprouts and starts growing. You can also divide crowns in autumn after the top growth dies back. If you divide in autumn, be sure to add several inches of aged compost or mulch over the planting bed to protect the crowns from freezing temperatures in winter.

  8. I live in Arizona and my asparagus never seem to turn brown or die back. My plants are about 4 to 5 feet tall. How do I know when to cut them back so I can add more soil in my raised bed?

    • The ferny asparagus stems are storing energy and nutrients for next season’s spears. You can cut them back to the ground in mid-fall or early winter (just as though they were experiencing the change of season from warm season to cold season). Once cut back you can more soil or mulch over the top of the bed.

  9. My asparagus bed is around 20 years old. I am in Oklahoma. Every summer small annoying trees invade my asparagus plants. Once the ferns are getting tall, the trees get out of control. They are larger than the asparagus ferns. Would it hurt the asparagus if I would try burning the ferns and trees in late winter when they were dormant?

    • The crowns of your asparagus plants are not far below the surface. Burning the asparagus ferns and trees would likely damage the asparagus crowns and could destroy in full or part your future harvests. The trees you spot in your asparagus bed are probably suckers growing from the roots of a nearby tree. Can you identify a nearby tree with similar leaves? If so, dig down 18 to 24 inches on the side of the raised bed where the tree is growing; you will likely find roots growing from the tree to the moisture in your raised bed. Slice these roots and insert a root guard of sheet plastic or sheet metal down into the soil as a barrier. Then carefully remove the tree suckers in the asparagus bed. If there are no trees nearby then the trees may be growing from seeds dropped by birds. Dig down and remove as much of the tree roots as you can.

      • Thank you so much for responding and for the information. Unfortunately, it us a large asparagus patch and numerous trees that digging up the roots would be almost impossible. I appreciate you taking the time for your advise.

        • Next time you are at the garden center ask for a sucker stopper; this is a spray that contains a systemic herbicide. Spray each sucker with this herbicide; to keep the herbicide from reaching the asparagus patch use newspaper, cardboard or a bottomless paper bag to surround the sucker then you spray it; this will keep the herbicide mist from drifting onto other plants.

  10. How much cold will the roots take in the winter. I am in the Yukon. I can cover with lots of straw but the bed will still experience freezing temperatures.

    • Asparagus roots can withstand temperatures as low as -40F. Protect the planting bed with a very thick layer of straw or aged compost and then straw on top.

  11. This March 21,2020 I will have have had my first year of asparagus in my raised bed of 8 x15ft. Here in Georgia, the weather is crazy and can go from 28 degrees to 80 degrees in 24 hours. I grew from seeds and they grew thick and bushy. So when I saw the first freeze coming, I cut them all to ground level, backfilled with manure, leaves and straw to keep warm. A couple of weeks later, they were , some of them were over two feet tall again. I have not been sure how to deal with this, except to cover with more straw and blankets on freezing nights and then take off during the day. Should I cut back down to the ground again or just leave them growing?ALot of what I cut back is still cut and looks dried up and dead. I sure hope they are not dead. I am a bit confused with this whole process as this is only the end of the first year, and some om my stalks are thick as my pinky already. Any suggestions would be appreciated, thank you, Greg

    • During the first two or three years of asparagus growing, the important growth is below ground as the roots grow large and strong. Even though your stalks are harvestable size, resist harvesting all but a few. The top growth is fueling the growth below the ground. Rather than cutting back top growth when unseasonable weather threatens, cover the top growth with row covers or straw and let nature take its course. As for the growth that was cut back and now looks dead, it may be. Simply wait to see if new green growth springs from the roots. If there is new growth, replace those plants with new crowns in the fall.

    • Yes, three-year-old asparagus plants can be harvested; the roots are established now and strong. Let the spears grow to the diameter of your little finger before you harvest.

  12. I live in a 5b zone and I bought seeds Id like to plant. It’s May 5th and I’m wondering if it’s too late to plant them this year, or should I go ahead anyway and have this year help to start building my roots.
    Thanks in advance for the advice.

    • It’s not too late to sow the seeds and get the plants started. Start the seed indoors and set out the transplants when they are 4 or 5 weeks old.

    • Sprinkle an organic commercial planting mix or aged compost around each plant and across the bed. Do this two or three times a year. These amendments contain all of the nutrients your asparagus needs.

  13. I have an asparagus bed that is 14 years old. When it ferns out, it has seeds that I have let drop. Now I have a lot of very skinny fernny plants intermixed with harvestable stalks. It is very crowded and I believe I have voles. I would like to start a new raised bed with screen for the voles. Can I dig up the areas that look overcrowded with early spring ferns and transplant. If so when would be a good time. My ferns stay green almost all year. Are the crowns less that a year or two old and can be transplanted or are they too old. Also, if I have more than I need and want to give some away, is that a good idea? If I was to transplant the crowns that have harvestable stalks, should I leave the whole crown intact. I haven’t dug them up yet and do not know what to expect. Any insight would be greatly appreciated. I live in the rain shadow in the northwest. It is now early spring.

    • Crowns that are 12 to 18 months old can be dug up and transplanted. The best time to transplant crowns or plants is late winter or early spring or in early fall. If your summer temperatures are moderate, not hot, you can transplant the crowns in summer. Leave the older established plants in place, and remove others that are crowding the bed. The younger plants can be used to establish a new bed–or can be given away. Plants older than two or three years should be left in place if possible.

  14. I have an area is my garden that is part sun and for some reason seems to have more rocks than the rest of the garden. Will asparagus grow in a rocky area like this

    • A shady, rocky location is not a desirable spot for asparagus. Choose a sunny location, remove the rocks, or plant asparagus in a raised bed.

  15. Thank you. You comments are wonderful. My father helped me plant the asparagus bed in 1973. I don’t think any of those have survived and the present ones have all seeded themselves. I have neglected the bed and plan to try your suggestions. They are overrun with weeds and they need compost The spring can be too wet However with your suggestions I know I can keep them gong and may try adding some where they won’t drown in a wet spring

    • Plant 6 to 8 weeks before the first expected frost; this will give the roots a chance to become established before the winter cold arrives. After the first frost, place a mulch of chopped leaves or straw over the planted crow to protect it from winter cole.

  16. I started asparagus for the first time from seed this year. I live in zone 3. I have about 18 plants in 4” pots and am building a raised bed for them. Is it too late to plant them? If it is how can I over winter them. And when I plant them should I separate the plants.

    • Chicken manure should be composted for several months before it is used around plants. Chicken manure is high in nitrogen which can burn plant roots and tender stalks. Let the manure compost in the hot sun for a few months before adding it to the garden. Add chicken manure in the fall and allow it to mellow through the winter. Wood chips are best used as a mulch around ornamental garden plants. Wood chips will shelter the soil from the hot sun and pounding rain, but they will draw moisture from the soil, which could be problematic for shallow-rooted vegetables. Wood chips are a good choice for pathways and around trees and large shrubs which are deeper rooted.

  17. I let my first asparagus spears grow too much and they ferned? Now they’ve stopped putting up new sprouts. Do I need to cut them back to spur more growth?

    • If the weather remains cool, trim back the tops and the crowns may push new spears. If the weather is not warming, you may want to let the tops grow on to store energy in the crowns for next year’s spears.

  18. I’m very much a beginner when it comes to gardening (this year is my first attempt at growing anything since the standard grow-a-bean-in-a-plastic-cup project in third grade.) I got a little over-zealous and bought asparagus crowns in mid-May, and I live in zone 8B. Is there anything I can do to give these a fighting chance, or did I pretty much spend 30 dollars on a lesson learned?

    • Asparagus is a long-term investment. Get the crowns planted right away; if they are still in the package, soak them in water for half a day before planting. Be sure to read this post: https://harvesttotable.com/how_to_grow_asparagus/ Keep the bed moist once planted; you should see green sprouts in 4 weeks or so. Let the asparagus grow on for a couple of years before you start harvesting. Let us know if you have specific questions.

  19. Oh, and I don’t have a way to get sufficient sunlight indoors, but I do have lots of shady areas outdoors and some large portable grow bags.

    • You will not be able to grow asparagus indoors; the ferny tops grow to four feet by the end of summer. You can try growing asparagus in grow bags, but asparagus begins producing edible spears in 3 years and will remain productive for 15 years.

    • You can set out asparagus crown in late summer. Be sure to heavily mulch them before the first freeze to protect them through the winter. If you plant now, the plants should establish some roots before winter.

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