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The Definitive Guide to Growing Asparagus In a Raised Bed

The definitive guide to growing asparagus in a raised bed

Plant asparagus once, and it’s the gift that keeps on giving… for 20 to 30 years!

That’s practically reaching heirloom status… Imagine passing down your asparagus bed to your kids one day?!

So when I finally had the space to grow asparagus in our garden, I wasted no time getting started. Why? Because even with the best fertilizer and care, asparagus takes a few years to fully hit its stride.

Being perennial, asparagus also need a dedicated, permanent plot in your yard where no other plants will go. Unlike many other crops, they don’t want companions and especially hate competition from grasses and weeds.

If you grow asparagus in a tall raised bed—by far the easiest approach—you’ll eliminate all of the digging, mounding, crouching, kneeling, and weeding that traditionally grown asparagus requires. A raised bed also helps the soil warm up faster in spring, so your asparagus will come up faster too.

Related: Lazy Gardening: 11 Time-Saving Tips for Getting More Out of Your Garden By Doing Less

Here’s how I recommend planting asparagus if you want an easy, low-maintenance method.

Asparagus crowns bundled inside purple mesh bags

When to buy asparagus plants

Asparagus crowns are only available once a year in early spring, so you have a short window to order or bring them home. Many reputable online suppliers even sell out in early spring, so start looking at their inventory in winter (when you’re also browsing seed catalogs) and place your order ahead of time.

Mail-order asparagus gets shipped according to your last frost date, so make sure you pick the correct delivery timeframe (which typically spans from March to May).

Read more: Know When to Grow: A Planting Calendar For Your Garden

Brick-and-mortar nurseries, garden centers, and farm stores start carrying asparagus crowns when they’re ready to be transplanted, so if you find them locally, you can plant them right away.

Asparagus crowns piled in a black tub at a garden center

When you buy asparagus plants, you’ll typically receive one-year-old crowns like you see here.

Close-up of hand holding an asparagus crown

This cuts down on the time you have to wait before you can harvest asparagus, and modern hybrid varieties are much easier to grow than heirlooms.

They look a little weird and gangly—kind of like spiders—and might not even look like they’re alive, but get them in the ground and they’ll spring up quickly.

One-year-old asparagus crown in the soil
Disclosure: All products on this page are independently selected. If you buy from one of my links, I may earn a commission.

Should you start asparagus from seed?

You could, but it’s just as easy to find asparagus crowns as it to find seeds, and you have a higher rate of success with crowns.

Not to mention, old-world cultivars like Martha Washington and Mary Washington (which are also available as seed) are fussier to grow than improved F1 hybrids like Jersey Knight and Millennium.

These modern hybrid varieties are less work to plant and they produce nearly twice as many spears per plant, since they’re bred to be predominantly male (which means the plants don’t waste energy on producing seeds and baby plants). They also tend to maintain tight tips, even if you’re a little slow to harvest.

Woman's hands holding bundle of green asparagus spears in a garden

With vigorous hybrids like the Jersey series (Jersey Knight, Jersey Supreme, and Jersey Giant), you only need 25 to 30 plants to feed a family of 4… unless you really love asparagus or plan to freeze or pickle them later, then the more the merrier.

Otherwise, the typical recommendation for growing an open-pollinated asparagus variety (like Martha Washington) is up to 10 plants per person—so you’d need a lot of real estate to devote to a single crop.

Read next: How Much to Plant in a Vegetable Garden to Feed a Family

How to plant asparagus in a raised bed

Once asparagus gets established, it doesn’t really like to be moved again. So find a good permanent spot in your garden (keeping in mind that asparagus ferns can grow up to 5 feet tall in a single season) to avoid transplanting the whole crop later.

Asparagus can be planted as soon as the soil is workable and your average last frost date has passed.

If the crowns look and feel a bit brittle (which is usually the case with store-bought asparagus that’s displayed in a big basket or tub), soak them in a bucket of water to rehydrate them before planting. You can do this while you prep the soil—just don’t leave the crowns in water for longer than an hour, as that can encourage rot.

View of asparagus crowns soaking in a green tub filled with water

Soil preparation

Choose a planting site on the northern or western side of a garden so mature asparagus plants won’t shade other vegetables in summer.

Start with well-draining soil that’s about 8 inches below the rim of your bed.

Raised bed filled with soil to 8 inches from the top

That means your raised bed needs to be at least 12 inches high to give the roots room to grow, though I recommend building a bed up to 24 inches high for easy harvesting. (My own asparagus bed is 36 inches high! And my back thanks me for it every season.)

Side view of a 3-foot-tall cedar raised bed

Clear the area of any weeds, and amend the soil with 2 inches of well-aged compost.

Mix in an organic all-purpose fertilizer, following the package directions. The best option, if you can find it, is an organic fertilizer that has higher levels of phosphorus and potassium. (These are the P and K values in NPK.)

Phosphorus promotes strong root growth so it’s especially important for asparagus in early spring. Potassium is needed for healthy crop production as it helps the plants develop sturdy stems (the part we eat, otherwise known as asparagus spears).

Close-up of soil amended with fertilizer with a trowel in the background

I also like to add kelp meal before planting. This organic amendment contains growth hormones that aid in root and shoot development, as well as trace minerals not found in NPK fertilizers.

I recommend this specific fertilizer from Dr. Earth or this one from Jobe’s Organics (don’t mind what they’re called, just look at the ingredients), plus a dose of kelp meal to get your plants off to a great start.

Planting

Most asparagus planting guides call for digging trenches and making mounds, but in a raised bed, you can skip all that work!

Place the crowns 12 inches apart and spread the roots out around them.

Asparagus crown with roots spread out around it
Raised bed with asparagus crowns planted in soil
Long rows of asparagus crowns planted in a raised bed

Make sure the crown is facing up. It’s the little nub that sits above the roots, and it’s where the asparagus will grow from. Sometimes, there will even be tiny spears sprouting already.

Close-up of asparagus plant with tiny spears emerging from the crown

Cover the asparagus with about 3 inches of soil.

Once the asparagus starts growing and the spears are a few inches tall, add another 3 inches of soil (taking you to the top of your bed—the crown should be 6 inches below the surface now). Then for the rest of the season, keep the weeds down with a 2-inch layer of mulch.

Asparagus crowns covered with soil inside a raised bed

Watering

During the first two years, asparagus needs regular watering (about 1 to 2 inches of water per square foot per week). Once established, the plants need only 1 inch of water per week.

As the plants get older, they become fairly drought-tolerant and usually grow well with rainfall as the sole water source (unless you live in a dry, hot climate).

Fertilizing

Asparagus is unique in that it’s fertilized in the beginning of the season, before the first shoots appear, and then fertilized mid-season (in June or July) after you’ve finished harvesting. This helps the fronds grow lush and healthy, which encourages massive yields the following year.

A bed of lush asparagus fronds

To keep nutrient levels high, you can apply the same organic fertilizer you mixed in during the initial soil prep (like these ones from Dr. Earth or Jobe’s Organics). I also like to add bone meal or rock phosphate in summer to replenish phosphorus levels.

How do I store asparagus crowns if I can’t plant them right away?

If you got a shipment of asparagus crowns in the mail but you aren’t ready to plant them right away, open up the box so the crowns can breathe and keep them in a cool, dark place for up to a week.

If you need to store the crowns longer than a week, you have a few options depending on space and timeline.

For short-term storage (another week or so), wrap the bundles in slightly damp kitchen towels or newspapers, and stash the crowns in a cool, dark place (like a pantry, closet, or basement).

For longer-term storage, you can wrap the bundles in damp towels or newspapers (or place them in a loosely sealed plastic bag) and keep in your refrigerator for several weeks. They might start sprouting during this period but as long they don’t dry out, the asparagus will survive. Ideal conditions are 40°F at 85 percent to 90 percent humidity.

Don’t let excess moisture accumulate on them (otherwise they’ll get moldy or rot). Periodically spray them with water if the roots look and feel dry, and plant them as soon as possible.

If your dedicated asparagus bed won’t be ready for a while, then it’s best to get the crowns in the ground temporarily. You can plant them closer together than normal (6 to 8 inches apart) and transplant the asparagus next spring when they’re still dormant. Just be gentle when you lift the roots to move them into their permanent bed.

When can you harvest the first asparagus from this planting?

The first year, don’t harvest any asparagus. (I know, it’s tempting.)

The next year after you plant them, you can take a very light harvest (just one or two spears per plant, over a three- to four-week period).

The year after that (which would make your plants three years old), you can start picking asparagus regularly through the harvest season, which runs about six weeks (and sometimes up to eight weeks).

Purple asparagus spears growing in soil

By not harvesting heavily during the first two years, you allow the crowns to be more productive over the life of the planting. It might sound counterintuitive compared to what you’re often told about other vegetables—that the more (and more frequently) you harvest, the longer your crop produces.

But when you allow asparagus fronds to unfurl and continue growing in the first two years, this helps the plants capture a greater amount of sunlight. All that energy goes into feeding the roots so the plants can develop a strong root system that supports an abundant crop of spears the following year.

I promise it’s worth the wait!

Green asparagus spears and asparagus ferns in a garden bed

How do you harvest asparagus?

Harvest your asparagus when the spears are 5 to 7 inches tall and before the tips begin to loosen. (Once the tips loosen, the spears become tough and fibrous.) To harvest the spears, just cut or snap them off right above the soil level.

Once your asparagus bed is established in its third year, harvesting can continue until the bed produces only skinny spears that are less than half an inch in diameter.

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At that point (usually late spring to early summer), allow the spears to develop naturally. They’ll grow 3 to 5 feet tall with lacy, fern-like, feathery soft foliage. The healthier they are, the better your crop will be the following spring.

Close-up of flowering asparagus frond

How do I prepare the asparagus bed for winter?

After the fronds turn brown in fall, you can either:

  • Let the dead foliage stand over winter (and cut it down in early spring before new growth appears).
  • Or you can cut the dead foliage down at the base of the plants before winter, and remove it to keep pests (like asparagus beetles) from overwintering.

If you had a problem with pests or diseases during the growing season, bag and trash the old foliage; it’s not worth adding to your compost pile, as many home compost piles don’t get hot enough to destroy eggs and pathogens.

You then have the choice of leaving the asparagus bed bare like that, if you get enough snow to cover and insulate the crowns all winter, or mulching the bed.

Mulching is a better option as it’ll protect the crowns from frost heaving if you get an early spring thaw followed by more freezing temperatures. You can use any type of organic mulch, such as straw, dried shredded leaves, wood chips, or pine straw (pine needle mulch).

Cover the bed with 4 to 6 inches of mulch. Once all danger of frost has passed in your area, push the mulch aside to help the asparagus spears emerge sooner. (Don’t worry if you forget to do this; they’ll still grow right through the mulch, but they’ll take a little longer to emerge.)

How long do asparagus typically live?

In the right environment with proper care, asparagus will live for a minimum of 10 years, but often last 20 to 30 years.

Lone asparagus spear growing in a mature asparagus bed

Common questions about growing asparagus

Close-up of Jersey Knight asparagus crown
About Author

I'm a plant lover, passionate road-tripper, and cookbook author whose expert advice and bestselling books have been featured in TIME, Outside, HGTV, and Food & Wine. The No-Waste Vegetable Cookbook is my latest book. Garden Betty is where I write about modern homesteading, farm-to-table cooking, and outdoor adventuring — all that encompass a life well-lived outdoors. After all, the secret to a good life is... Read more »

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