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How to Plant, Grow, & Harvest Asparagus

Asparagus, the herald of spring, is a beloved delicacy in the culinary world. Its sweet, tender shoots emerge when most gardens are still dormant, providing an early bounty for the kitchen. 

But did you know that this perennial vegetable is surprisingly easy to cultivate? Follow our handy guide to learn the secrets of planting, growing, and harvesting asparagus.

Planting

There are a few things you should figure out before planting your asparagus for the first time:

Asparagus Varieties to Grow

Asparagus, a plant of the lily family, is an intriguing character in the vegetable kingdom. Its below-the-surface life is a rich tapestry of diversity that belies its simple, slender appearance above ground.

This perennial veggie comes in an array of varieties, each with its unique strengths and flavors. 

Recent cultivars have been primarily bred to be all male, focusing their energy on plant growth instead of seed production. This strategic breeding has resulted in varieties that are not only highly productive but also possess enhanced disease resistance:

Asparagus in hand
  • Mary Washington, the most widely grown variety, is celebrated for its hardiness and resistance to rust.
person cutting Asparagus seed plant
  • Jersey Giant is another champion variety that makes its presence felt early in the season and stands up well against rust and fusarium wilt.
Asparagus seed plant
  • If you’re after a high yield, consider Brock Imperial.
Asparagus in purple shade
  • And for something a little different, Purple Passion offers sweet, thick spears that add a splash of color to your garden and your plate.

Green Asparagus vs. White Asparagus

Green Asparagus vs. White Asparagus

The green asparagus we commonly see is just one side of the asparagus coin.

Through a process known as blanching — depriving the plant of light to prevent photosynthesis — white asparagus is created from the same plant. The harvested spears are covered with soil or plastic tunnels while they grow, yielding a smooth, white product that’s virtually fiber-free. 

Remember: Once harvested, these delicate white spears should be chilled immediately to stop fiber formation. 

Green or white, purple or classic, each asparagus variety brings its unique taste and texture to culinary creations around the world.

When & Where to Plant

Timing and location are crucial for asparagus planting.

Asparagus can be started from seeds about four weeks before the last expected frost, but this method lengthens your waiting period.

Most gardeners prefer to plant asparagus from crowns, which are widely available in spring. Unlike many other plants, the roots of asparagus crowns can endure some air exposure, so you’ll usually find them sold as bare roots. Look for firm and fresh crowns, avoiding those that appear withered or mushy.

The best time to plant is in early spring when soil temperatures reach 50°F.

Selecting a planting site for your asparagus calls for strategic thinking. Your asparagus spears may take up to three years to mature enough for harvest, so it’s vital to prepare a bed that will offer the best growth conditions over this long gestation period.

Because asparagus is a perennial, you’ll need to dedicate a spot in your vegetable garden exclusively for it, or better still, create a separate bed.

Related: What to Plant in a Raised Garden Bed

Remember: When you plant asparagus, you’re making a commitment that could last up to 25 years! This longevity makes proper soil preparation and the right location vital from the get-go.

Spacing, Depth, and Support

Asparagus plants need room to breathe and grow.

When it comes to spacing your asparagus crowns, the rule of thumb is to allow 12 to 18 inches between each. They may seem isolated in their early years, but once settled, they flourish rapidly.

It’s important to note that heirloom varieties require additional space due to their dual male and female nature; they produce seeds and can self-sow. On the other hand, newer hybrid varieties, which are entirely male and seedless, can be planted a bit closer as they will spread only through the growth of the existing crown.

Learn More: How Many Asparagus Plants Per Square Foot?

Planting Instructions

The most popular method of planting asparagus crowns involves digging a trench. Here are the instructions:

  1. Come springtime, dig a trench about 12 inches deep and wide.
  2. Mix in your compost, fertilizer, or other organic matter into the dug-out soil and form mounds approximately 18 inches apart.
  3. Place the crown at the top of each mound, draping the roots down the sides. The crown’s peak should sit about 6 inches below the soil surface.
  4. Cover it partially with soil and water generously.
  5. As new shoots emerge, continue adding soil until the trench aligns evenly with the surrounding soil line.

Weeds are unwelcome guests when preparing your asparagus bed and during the plants’ infancy. Asparagus roots weave a dense mat that makes it difficult to extract weeds later on. Therefore, regular weeding is crucial in the early stages of growth.

To help control weeds, consider adding mulch to your bed. Avoid interplanting asparagus with other crops; these perennials are not fans of competing for nutrients.

While support isn’t necessary initially, incorporating stakes as your asparagus plants mature could safeguard them against wind damage. With these guidelines in mind, you’re well on your way to nurturing a thriving asparagus bed!

Growing

seed plant Growing

Once your asparagus is planted, you need to make sure you’re meeting all the plant’s essential requirements for productive growth:

Soil pH & Composition

Asparagus thrives in loose, fertile, and well-draining loamy soil.

Before planting, ensure that your ground is free from rocks and heavy, clay-like clumps which could hinder the roots’ expansion. Boost your soil’s fertility by generously adding organic matter and well-decomposed compost while also removing any debris which could obstruct the spread of plant roots.

When it comes to pH balance, asparagus has a slight preference for acidity over neutrality. The ideal pH range for asparagus cultivation is between 6.5 and 7.0. Straying too far on either side of this scale may affect the availability of essential nutrients for the plant, thereby stifling its growth.

Learn More: What Are the Asparagus Soil Requirements to Grow Well?

Light 

To ensure robust and healthy asparagus, choose a location in your garden that revels in full sun — your plants will need at least six to eight hours of direct sunlight each day to reach their fullest potential.

Without sufficient daily sunlight, your asparagus could end up frail and feeble, producing only thin spears and becoming susceptible to a myriad of problems.

Temperature & Humidity

Though hardy enough to withstand temperatures as low as -20°F once fully established, asparagus shines brightest in moderate climates with a winter chill period.

During the growing season, asparagus gravitates toward daytime temperatures ranging from 70°F to 85°F and appreciates cooler evenings between 60°F to 70°F. Come spring, as the soil temperature nudges its way up to 40°F, your asparagus plants will start sprouting shoots. 

However, be warned: any unexpected frost after this growth spurt can inflict damage on these delicate shoots.

Growers may also notice a sluggish growth rate if temperatures soar above 85°F or plummet below 55°F — so keep a keen eye on those thermometers.

Water

Especially in its early years, asparagus plants have quite a thirst.

Aim to quench their need for hydration with 1 to 2 inches of water per week during the first two growing seasons. A steady supply of water during these formative years not only encourages robust development but also lays the foundation for stronger, more resilient plants in the future.

Once matured, asparagus plants tap into their inherent drought tolerance, requiring about an inch of water per week.

To ensure your asparagus bed receives consistent watering, consider installing a drip irrigation system or a soaker hose. These watering methods can provide a steady supply of moisture directly to the roots where it’s most needed, reducing waste and promoting deeper root growth.

Fertilizer 

When preparing your asparagus bed, don’t hold back on enriching the trench with compost and an all-purpose organic fertilizer. Adding rock phosphate, a natural mineral powder, can also boost root growth and help your asparagus plants establish a robust root system.

Related: How Long After Fertilizer Can I Seed?

To maintain nutrient-rich soil that continuously feeds your asparagus plants, consider an annual top dressing of compost. This can be done in early spring before the shoots make their debut or in fall after the fronds have died back and been cut down to ground level.

Remember, asparagus is a heavy feeder. It craves nutrients when it’s actively growing in mid-spring. Following this growth spurt, replenish the soil with another round of fertilizer, adhering to product label instructions for best results.

Pests & Diseases

Despite its delicate appearance, asparagus is a resilient warrior in the garden, standing strong against most pests and diseases. However, there are a few foes to keep an eye out for:

  • Fusarium wilt can pose a problem, particularly with older asparagus varieties. This soil-borne disease can cause yellowing and wilting of ferns, ultimately leading to plant decline. The good news is you can sidestep this issue by opting for resistant hybrid varieties which are bred to stand up against this disease.
  • The biggest adversary of asparagus is the asparagus beetle. With a keen eye, you’ll spot these troublesome pests as the spears emerge in spring. They’re most active in the afternoon, making it an ideal time to hunt them down. If the infestation is small, handpick these beetles and drop them into a bucket of soapy water. For more extensive invasions, diluted neem oil should help keep these pests in check.
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Related: 8 Natural Pest Control Methods for Your Garden

Harvesting

Harvesting asparagus is a masterclass in patience. The reward for this patience? An annual bounty of fresh, succulent spears that can continue for up to 20 to 30 years.

Harvesting

Here’s what you can expect during the initial years of your asparagus journey:

  • In the first year, your asparagus plants need time to establish themselves and develop strong root systems. The shoots may not be large at this stage, but resist the temptation to harvest any spears. This grace period is crucial for their future productivity.
  • During the second year, some gardeners might be tempted to harvest spears that are the thickness of a pencil or more. However, for robust, well-established asparagus plants, exercising patience pays off in the long run.
  • By the third year, you should be able to start reaping the fruits of your labor — or in this case, the vegetables. You can begin harvesting for about two weeks when spears are roughly 8 inches tall and still firm. After this brief harvest window, let new spears grow undisturbed. Fronds will unfurl from these spears, creating pretty, airy foliage that nourishes the plant.
  • By the fourth year, you’re fully in harvest mode. Start by snapping off spears that are 5 to 7 inches long before the tips become loose. Diameter isn’t important here; focus instead on length and firmness. You can use your hands or a knife to do this — just be careful not to harm any underground shoots that haven’t surfaced yet.
  • From the fifth year onwards, it’s time to reap your well-earned rewards! You can harvest for around four to six weeks each year. As the weather warms up and the shoots start thinning out after a month of harvesting, allow your asparagus plants to grow into their mature ferny foliage. This lush growth feeds the roots and prepares them for next year’s crop.

In subsequent years, remember that overcrowded or struggling plants can benefit from division or transplantation.

Overwintering

Each year, asparagus plants need to be cut down to the ground before the emergence of new growth. You can choose to do this in either fall or winter once the leaves have yellowed and naturally died back. 

Cutting back asparagus early in the fall has its advantages. It helps prevent pests like asparagus beetles from hibernating within the stalks, thereby reducing the likelihood of an infestation in the following spring.

However, there’s also merit in leaving the stalks standing through winter. The plant debris can act as a snow-holder, providing a protective layer over the asparagus crowns during freezing temperatures.

Regardless of when you choose to cut back your asparagus, one thing is non-negotiable: all dead stalks must be removed by spring before new growth begins. This practice paves the way for a fresh start each growing season, ensuring your asparagus bed continues to flourish year after year.

Conclusion

Planting, growing, and harvesting asparagus may appear daunting at first. After all, it’s not every day that you commit to a garden plant that sticks around for a quarter of a century!

However, with the right knowledge and a little patience, nurturing a flourishing asparagus bed is within every gardener’s grasp. From selecting the perfect variety and planting site to mastering the art of watering and fertilization, every step brings you closer to enjoying home-grown asparagus spears.

The journey may be long, but each spring’s bounty will remind you why it’s worth every moment — whether lightly steamed or grilled on the barbecue, nothing compares to the taste of fresh asparagus harvested from your own garden. Happy gardening!

FAQ

Why does it take three years to grow asparagus?

Asparagus is a plant that requires patience. It takes about three years from the time of planting for asparagus to fully mature and produce harvestable spears. This is because asparagus needs time to establish a strong root system that will support the production of succulent spears year after year.

For the first two years, instead of harvesting the spears, you’ll let them fern out and feed the growing root system below. From the third year onwards, you can enjoy annual harvests for up to 25 years if well-maintained.

How much asparagus do you get from one plant?

The yield from an asparagus plant can vary depending on its age and growing conditions. However, once fully established (around the third year), you can expect each crown to produce approximately half a pound of spears per season.

So, if you plant 10 crowns, you should get about 5 pounds of asparagus each year.

Can I grow asparagus in pots?

Yes, you can grow asparagus in pots, especially if you are dealing with space constraints or poor soil conditions.

However, remember that asparagus has a deep and extensive root system and therefore requires large containers — at least 18 inches deep and wide.

Also, note that container-grown asparagus may not be as prolific or long-lived as those grown directly in the ground due to restricted root growth.

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