How To Grow Asparagus

Asparagus is a perennial vegetable that, once established, can provide a bountiful harvest for many years, often up to 20 years or more.

Unlike most vegetables, asparagus plants are long-lived, which makes them a fantastic investment for a dedicated spot in your garden.

Published: April 25, 2024.

Intro To Asparagus

Asparagus, known scientifically as Asparagus officinalis, is a hardy perennial that is one of the first crops to sprout in spring. Originating from maritime regions of Europe and Asia, this vegetable has been a gourmet delight since ancient times.

It's known for its succulent, spear-like shoots which, when harvested young, offer a sweet and slightly nutty flavor that's highly sought after in culinary circles.

The cultivation of asparagus can be a rewarding endeavor for the patient gardener, as the plant requires several years to become fully established.

However, the wait is worthwhile, as a well-maintained asparagus bed can produce an abundant crop that reappears reliably every spring. This enduring nature makes it an excellent addition to any garden, especially for those looking to cultivate a sustainable, long-term vegetable plot.

Asparagus Ideal Growing Conditions

Asparagus thrives under specific conditions that mimic its native coastal habitat. It prefers a temperate climate but is adaptable enough to grow in a range of environments if cared for properly.

The key to success begins with the soil: asparagus needs well-drained, sandy loam soil rich in organic matter. It prefers a slightly alkaline pH between 6.5 and 7.5.

Sunlight is another critical factor for asparagus; the plants need full sun for a minimum of six to eight hours per day to develop properly.

Adequate spacing is also crucial to prevent overcrowding and to promote air circulation, which helps minimize the risk of disease. A site that has not previously hosted asparagus or related crops for several years is ideal, as this reduces the likelihood of encountering soil-borne diseases.

How Long Does Asparagus Take to Grow?

Growing asparagus requires patience, as it is a long-term crop that takes several years to establish fully before you can begin harvesting substantial yields. The duration from planting to full production depends on whether you start from seeds or crowns.

Growing Asparagus from Crowns

• Planting the Crowns: Crowns are one-year-old asparagus plants that are typically planted in the spring. These are the dormant roots of asparagus plants and are widely used because they provide a quicker path to harvest compared to starting from seed.
• First Year: After planting the crowns, spears begin to emerge in the spring. These spears should not be harvested in their first year after planting as the plant needs to invest energy into establishing a robust root system. During this period, the spears will grow and fern out, the ferns aiding photosynthesis and strengthening the underlying root system.
• Second Year: In the second year, you may harvest a few spears sparingly over a very short period (about two weeks). This limited harvest allows the plants to continue to strengthen their root systems.
• Third Year and Beyond: By the third year, the root system should be well-established, and the plants can support a longer harvesting period—typically about 4 to 6 weeks. Each year, as the plants mature, the yield should increase, with full production reached by about the fourth or fifth year.

Growing Asparagus from Seeds

• Sowing the Seeds: Starting asparagus from seeds is less common for home gardeners due to the additional time required. Seeds can be sown indoors in the early spring or directly in the garden. They usually take about three weeks to germinate.
• First Year: Seedlings grown from seeds spend their first growing season developing a basic root system and foliage. These plants are much smaller than those started from crowns and are typically not ready to transplant until they are one year old.
• Second Year: After transplanting one-year-old seedlings (which are now effectively crowns), the plants will follow a similar timeline as those started directly from crowns. No spears are harvested during this year as the plants are still establishing.
• Third Year and Beyond: Like the crown method, harvesting begins sparingly in the third year and becomes more regular by the fourth and fifth years, once the plants have a well-developed root system.

Overall Timeline

• From Crowns: Approximately 3 years until the first meaningful harvest, with full production by years 4-5.
• From Seeds: Approximately 4-5 years until the first meaningful harvest, considering the extra year needed to grow the seedlings to crown size before transplanting.

Asparagus is a rewarding crop for those willing to invest the time. Once established, asparagus beds can be productive for up to 20 years, making them a valuable addition to any garden.

Proper care and management during the establishment phase are critical to ensuring a healthy, productive asparagus bed.

How to Plant Asparagus Crowns

Planting asparagus crowns correctly is crucial for establishing a productive asparagus bed that can yield harvests for many years.

• Choose the Right Time: Asparagus should be planted in the early spring as soon as the soil can be worked. It's important to plant the crowns before they begin to dry out or sprout significantly.
• Select a Suitable Location: Choose a location in your garden that receives at least 6-8 hours of direct sunlight daily. Asparagus also requires well-drained soil to prevent root rot, so avoid areas where water tends to collect. Since asparagus is a perennial, ensure the chosen spot won’t require disturbance for many years.
• Prepare the Soil: Asparagus thrives in nutrient-rich soil. Prepare your planting bed by removing all weeds and debris. Loosen the soil to a depth of about 12 to 15 inches and mix in 2 to 4 inches of compost or well-rotted manure to improve fertility and drainage. This also helps to create a loose bed that allows for easy root growth.
• Dig a Trench: Create a trench that is about 6-8 inches deep and 12-18 inches wide. If planting multiple rows, space the trenches about 4 to 5 feet apart to give the asparagus ample room to grow.
• Prepare the Crowns: Before planting, soak the asparagus crowns in water for 15-20 minutes to hydrate them. This can help give them a little boost and improve their viability.
• Plant the Crowns: Place the crowns in the trench about 12 to 18 inches apart. Spread the roots out uniformly around the crown, resembling a spider sitting in the trench. Ensure the buds are pointing upwards.
• Cover the Crowns: Initially, cover the crowns with only 2 to 3 inches of soil, leaving some of the roots exposed. As the asparagus begins to grow and the stems start to emerge, continue filling in the trench gradually with soil until it is level with the ground surface. This method helps protect the young spears from damage.
• Water Thoroughly: After planting, water the bed thoroughly to settle the soil around the crowns. Keep the area moist but not waterlogged, as asparagus does not like to sit in wet soil.
• Mulch the Bed: Apply a layer of organic mulch, such as straw or shredded leaves, around the plants. This will help retain moisture, suppress weeds, and keep the soil temperature stable.
• Fertilize: Although not necessary immediately after planting, consider applying a balanced fertilizer early in the subsequent growing season to promote strong growth. Use a fertilizer low in nitrogen but high in phosphorus and potassium to encourage good root development.

Care Tips

In the first year, allow the asparagus to grow without harvesting to ensure that the plants can establish a strong root system. It's very important to keep the bed free of weeds and to watch for signs of pests or disease.

How To Grow Asparagus From Seeds

Growing asparagus from seeds is a rewarding but lengthy process. It’s generally more economical than planting crowns and offers a broader variety of choices in terms of asparagus types.

If you have the patience for a slower start, growing asparagus from seeds can be a valuable gardening venture.

• Selecting Seeds: Choose high-quality seeds from reputable suppliers. Look for disease-resistant varieties to ensure the healthiest plants. Popular varieties include 'Mary Washington', 'Jersey Knight', and 'Purple Passion'.
• Start Seeds Indoors: Asparagus seeds have a long germination period, typically 2-8 weeks, so starting them indoors can help you get a head start. Begin by planting seeds in individual pots or a seed tray filled with a good quality seed starting mix. Plant the seeds 1/2 inch deep, and keep the soil consistently moist but not waterlogged.
• Provide Optimal Conditions: Keep the seed trays in a warm spot to encourage germination. Asparagus seeds germinate best at temperatures between 70-85°F (21-29°C). Once sprouts appear, provide plenty of light either by placing seedlings near a sunny window or under grow lights.
• Care for Seedlings: As the seedlings grow, keep the soil lightly moist and provide at least 12-16 hours of light daily. Fertilize the seedlings with a half-strength balanced liquid fertilizer every few weeks to support healthy growth.
• Harden Off Seedlings: Before transplanting outdoors, it’s important to harden off the seedlings. This process involves gradually acclimating the young plants to outdoor conditions. Begin about two weeks before planting by setting the seedlings outside in a sheltered location for a few hours each day, gradually increasing their time outdoors.
• Prepare the Garden Bed: While the seedlings are hardening off, prepare the garden bed. Asparagus prefers well-drained, fertile soil in a sunny location. Work in plenty of aged manure or compost to enrich the soil and ensure it’s loose and well-tilled. Consider raising the bed to improve drainage if needed.
• Transplant Seedlings: When seedlings are about 10-12 weeks old and frost danger has passed, they can be transplanted to the garden. Plant them in a trench about 6 inches deep and 12 inches wide, spacing seedlings about 12-18 inches apart within the row. Cover the roots with soil and water well.
• Care After Planting: Keep the bed weed-free and water regularly, especially during dry spells. Asparagus is a deep-rooted plant, so deep, infrequent watering is preferable to shallow, frequent watering. Apply mulch around the plants to help retain soil moisture and suppress weeds.
• Wait to Harvest: Patience is key when growing asparagus from seeds. Avoid harvesting any spears in the first two years after planting. Allow the plants to grow into ferns, which will help strengthen the root system. In the third year, you can begin to harvest lightly over a three-week period, gradually increasing the harvest period as the plants mature.
• Ongoing Care: Each fall, after the foliage has died back, cut the asparagus back to the ground. Apply a layer of compost or manure to nourish the plants and prepare them for the next growing season. Monitor for pests and diseases and manage them promptly to keep the plants healthy.

Growing asparagus from seeds requires more initial effort and patience compared to planting crowns, but it offers the satisfaction of nurturing the plants from the very start.

With the right care, your asparagus garden can thrive and produce bountiful spears each spring for many years.

How to Care For Asparagus

Once planted, asparagus requires a few years to establish itself fully. During this period, it's crucial to keep the beds weed-free and well-watered.

Asparagus plants are deep-rooted and can tolerate moderate drought, but they perform best with consistent moisture, especially during the spear-growing season.

Apply a balanced fertilizer in early spring just as the new spears begin to emerge to promote vigorous growth. Additionally, each fall, after the foliage has died back, cut the asparagus back to the ground to discourage pests and diseases.

Mulching the bed with organic material can help retain moisture, suppress weeds, and provide nutrients as it decomposes. Regular monitoring for common pests like the asparagus beetle is vital to protect your crop.

Asparagus Pest and Diseases

Asparagus, while a generally hardy plant, can be susceptible to a variety of pests and diseases that can affect its growth and productivity.

Knowing how to identify and manage these challenges is crucial for maintaining a healthy asparagus crop.

Common Pests of Asparagus

• Asparagus Beetle: The most common and damaging pest of asparagus is the asparagus beetle, which comes in two varieties: the common asparagus beetle and the spotted asparagus beetle. Both types feed on the foliage and lay eggs on the spears, which can scar the shoots and reduce market quality. The larvae can defoliate plants if left unchecked.

Control: Regular monitoring and hand-picking of beetles and larvae early in the season can significantly reduce populations. Organic options include neem oil and insecticidal soap. For severe infestations, approved pesticides might be necessary. Encouraging natural predators, such as ladybugs and lacewings, can also help manage beetle numbers.

• Asparagus Miner: This pest is a small fly whose larvae tunnel within the stems, weakening the plants. The damage can also provide entry points for fungal pathogens.

Control: Good sanitation practices, such as removing and destroying affected plant parts, are essential. Soil cultivation around the plants can help disrupt the life cycle of the miner.

• Cutworms: These caterpillars are active at night and can cut down young asparagus spears just above the soil surface.

Control: Keeping the field free of weeds and debris can reduce cutworm problems. Applying diatomaceous earth or beneficial nematodes around the base of plants can also be effective.

Common Diseases of Asparagus

• Fusarium Wilt: Caused by Fusarium oxysporum, this fungal disease leads to yellowing and wilting of ferns and can severely weaken the plant over several seasons. The fungus affects the vascular system, restricting water flow within the plant.

Control: There is no effective treatment for plants once infected; therefore, prevention is crucial. Plant resistant varieties, ensure good drainage, and avoid over-crowding. Crop rotation is also recommended where past infections have occurred.

• Asparagus Rust: This fungal disease, caused by Puccinia asparagi, appears as orange or reddish spots on the ferns, which can reduce the vigor of the plant. Over time, heavily infected ferns may die back prematurely, weakening the roots.

Control: Plant rust-resistant varieties if possible. Proper sanitation, such as removing old plant debris at the end of the season, is crucial. Fungicidal sprays can be applied when initial rust symptoms are observed.

• Crown and Root Rot: Various pathogens, including Phytophthora and Pythium species, can cause root and crown rot, leading to stunted growth and eventual plant death.

Control: Ensure well-drained soil and avoid over-watering to prevent these pathogens. Raised beds can also help improve drainage. Using fungicides may be necessary for severe cases or high-value commercial plantings.

• Purple Spot: Caused by the fungus Stemphylium vesicarium, the purple spot produces small, purple lesions on the spears and ferns. This can lead to reduced photosynthesis and weakened plants.

Control: Minimizing leaf wetness by improving air circulation and avoiding overhead irrigation can help manage this disease. Applying fungicides during wet seasons may also be necessary to protect the crop.

Regular crop monitoring, using disease-resistant varieties, implementing cultural practices to reduce habitat for pests and diseases, and using chemical controls only as a last resort, helps in maintaining the health of the asparagus crop but also promotes environmental sustainability by minimizing the use of harmful chemicals.

Asparagus Harvest and Storage

The anticipation builds over a few years, but once your asparagus is established, you can begin harvesting the spears in the third year after planting.

Harvest asparagus by snapping off the spears at ground level when they are about 6 to 8 inches tall and before the tips begin to open. Early morning is the best time for harvesting when the spears are firm and crisp.

Harvest season typically lasts for several weeks in the spring. After the initial few weeks, allow the plants to grow into their fern-like foliage, which will help them gather energy for the next year's crop.

Store harvested asparagus spears in the refrigerator, where they can keep for a few days. For longer storage, blanching and freezing the spears is an effective method to preserve their quality.

Few Final Words

Growing asparagus requires patience and commitment, but the rewards of harvesting your own fresh spears each spring are well worth the effort.

Whether blanched, grilled, or steamed, asparagus remains a versatile and nutritious addition to any meal, marking the arrival of spring with its tender shoots.

For more about this topic, feel free to check the following:

• Asparagus Companion Plants