How to Grow Asparagus: The Ultimate Guide for Thriving Perennial Harvests

Asparagus (Asparagus officinalis) is one of the earliest harvested vegetables each spring. Asparagus spears are crisp, juicy, and flavorful. Known for its longevity, this perennial plant can yield fresh, tender spears for over 20 years if cared for properly, although you won’t get a crop for the first couple of years. Let’s explore all the ways to grow asparagus—from planting through harvesting!

About the Asparagus Plant

Asparagus is not only delicious and hardy, but it’s also a unique perennial vegetable, returning year after year. However, you should avoid harvesting it during the first couple of seasons to allow it to become well-established. And after that, asparagus will send up new spears every few days for a few weeks in the spring, as they are relative fast producers. Patience is required, and the wait is well worth it for the delicious spears.

Asparagus officinalis

Key Features

• Scientific Name: Asparagus officinalis

• Mature Size: 4-5 feet tall, 1-3 feet wide

• USDA Growing Zones: 3-10

• Expected Planting Period: Spring or fall, depending on climate

• Days to Maturity: 2-3 years after planting crowns

• Growth Rate: Moderate once established, slow during early years

• Blooming Time: Early summer (small, inconspicuous flowers)

• Attributes: Perennial vegetable, drought-tolerant once established, cold-hardy, and requires patience during the first few years.

Varieties

Asparagus remains productive for so long, so selecting the right variety for your growing zone is essential. Here are some popular varieties:

• Mary Washington: A classic heirloom variety known for its disease resistance and productivity. It’s well-suited for zones 3–8.

• Jersey Series (Jersey Giant, Jersey Knight, Jersey Supreme): These hybrid varieties are high-yielding, disease-resistant, and produce mostly male plants (which are more productive). They thrive in zones 4-7.

• Purple Passion: Known for its beautiful purple spears, it is sweeter and more tender than green varieties. Suitable for zones 3–8, it also adds color to your garden!

• White asparagus: This is not a separate variety but the result of a special growing technique. Popular in Europe, it requires more labor but rewards gardeners with tender texture and a unique flavor.

Asparagus plants are either male or female! Male plants tend to be more productive because they don’t put energy into producing seeds, while female plants do. Female asparagus plants produce berries (that contain seeds), and this energy use can reduce the size and number of spears. For this reason, growing male asparagus plants is often preferred.

• Modern hybrid varieties, like ‘Jersey Giant,’ ‘Jersey Knight,’ and ‘Jersey Supreme’ are primarily male. These varieties have been bred to produce mostly male plants, making them more productive since they don’t use energy on seed production.

• Some older, traditional varieties like ‘Martha Washington’ and ‘Purple Passion’ include both male and female plants.

Should I plant seeds or crowns?

While you can start asparagus from seeds, most gardeners prefer using crowns (one-year-old plants) for faster establishment and earlier harvest. Starting with crowns eliminates the years of tedious weeding that come with starting from seed and speeds up production overall. Growing from seeds takes longer and may delay your harvest by an additional year or two.

Planting Asparagus

When to Plant

• Spring: For gardeners in cooler climates, spring is the ideal time to plant asparagus crowns once the soil can be worked and warms to 50°F (10°C).

• Fall: In warmer climates (zones 8–10), you can start planting as early as late winter to allow crowns to establish during the cooler months.

Where to Plant

• Choose a site with well-drained, sandy, loamy soil that receives full sun (6–8 hours of direct sunlight) since asparagus will remain in the same spot for decades. Avoid areas prone to waterlogging, as the roots can rot. Raised beds or mounded rows improve drainage in wetter regions. Learn how to make a raised garden bed here.

• Ensure the planting bed is free from perennial weeds, as asparagus does not tolerate competition. The soil should be neutral to slightly acidic, with a pH of about 6.5.

How to Plant

A few varieties, such as Purple Passion and Sweet Purple, can be grown from seed. You should start your seeds indoors in spring and set out the seedlings when they are 12–14 weeks old, just after your last spring frost.

• Soak the seeds in water for up to 24 hours before sowing.

• Sow them in moist peat or seed-starting soil in trays or peat pots. Once the seedlings grow to about 12 inches tall, gradually acclimate them to outdoor conditions over the course of a week.

• After the final spring frost, transplant the young plants into a temporary garden bed. In the fall, identify the male asparagus plants (which won’t produce berries) and move them to their permanent spot, while removing the less productive female plants.

Asparagus seedlings growing in small fabric pots inside a greenhouse

How to plant Asparagus

• Prepare the Bed: Dig trenches about 6–12 inches deep and 12–18 inches apart. Amend with organic compost and aged manure for a nutrient-rich environment. If digging more than one trench, space the trenches at least 3 feet apart.

• Planting Crowns: Space crowns 12-18 inches apart in the trench, spreading the roots outward. Cover crowns with 2-3 inches of soil initially, then gradually fill the trench as the plants grow.

  Tip: Soak crowns briefly in lukewarm water before planting to hydrate them, ensuring the roots are moist and ready for establishment.

• Once the trench is filled, add a 4-6 inch layer of organic mulch to retain moisture and suppress weeds.

Gardener hands planting Bare Root Asparagus (Asparagus Officinalis) in home garden field soil.

Growing Asparagus

Fertilizing

• Asparagus is a heavy feeder. To encourage strong root growth, apply a balanced fertilizer (such as 10-10-10) in early spring before spears emerge and again after the final harvest. Consider an organic fertilizer during the growing season.

• Avoid harvesting asparagus spears during the first two years to allow the plant ample time to develop a strong root system. In late fall, after the foliage has died back, cut it down to the ground. At this time, side-dress the plants with a layer of compost to enrich the soil, boost nutrient levels, and improve soil structure, preparing the plants for healthy growth in the following season.

Water and Soil Care

• During the first two years, while the plants establish their roots, aim to water them deeply about once a week, providing around 1-2 inches of water. Make sure the soil drains well to prevent root rot.

• Once the plants mature, they are quite drought-tolerant, so only water during prolonged dry periods. Mulching around the base can also help retain moisture and suppress weeds.

• Keep the soil consistently moist but not waterlogged during the growing season. Established plants can tolerate dry spells, but new plantings should never dry out completely.

• Asparagus benefits from annual top-dressing with compost or well-rotted manure, which also helps maintain soil fertility.

Pests and Diseases

• Common Pests: Asparagus beetles can defoliate the plant and reduce yield. Hand-pick the beetles or use organic insecticidal soap.

• Diseases: Fusarium crown rot and rust are common fungal diseases. Proper spacing for good air circulation, crop rotation, and avoiding waterlogged conditions can help prevent these issues.

While asparagus is typically grown in the ground, it’s possible to grow it in large containers. Choose pots that are at least 18 inches deep to accommodate the extensive root system. Ensure excellent drainage, and use a high-quality potting mix amended with compost.

Harvesting and Storing Asparagus

Harvesting

• You’ll need to be patient with asparagus. The first harvest usually occurs in the third year after planting crowns. During this time, allow the plant to focus on root development by not cutting spears.

• In the third year, begin harvesting when spears are about 6–8 inches tall and about the thickness of a pencil. Use a sharp knife or garden shears to cut the spears just below the soil line, or gently snap them off at ground level. Harvest every 1-3 days during the growing season.

• If spears grow too tall (more than 10 inches), let them turn into ferns. This helps the plant store energy for next year’s growth.

• The harvest season lasts about 4-6 weeks, then allow the spears to grow into ferns, which will feed the plant for next year’s harvest.

• Once the spears become thinner, it’s time to stop harvesting for the season and allow the plants to fern out and recharge.

Harvesting the asparagus 

Storing Asparagus

• Fresh asparagus can be stored in the refrigerator for up to a week. To keep it fresh, stand spears upright in a glass of water or wrap the cut ends in a damp paper towel.

• For long-term storage, blanch asparagus spears for 2-3 minutes, then freeze them in airtight containers.

Tips and Tricks

• Don’t rush the harvest in the first two years. Healthy root development is crucial for long-term productivity.

• Mulching not only retains soil moisture but also keeps weeds at bay.

• In late fall, after the ferns have died back, cut them to the ground to reduce disease risk.

• If you notice a decline in production after many years, consider rotating your asparagus bed or refreshing the soil.

Frequently Asked Questions

1. How long does it take to grow asparagus?
   Asparagus takes 2-3 years to mature fully from crowns. From seeds, it may take 3-4 years before the first harvest.

2. Can asparagus grow in containers?
   Yes, asparagus can be grown in large containers, though it requires deep pots and consistent care.

3. How do I know when to stop harvesting asparagus?
   Stop harvesting after 4-6 weeks or when spears become thinner than a pencil. Let the remaining spears grow into ferns.

4. What is the best variety of asparagus for beginners?
   Jersey Knight and Mary Washington are excellent choices for beginners due to their disease resistance and reliable yields.

5. How can I prevent asparagus beetles from damaging my plants?
   Hand-picking beetles and using organic insecticides can help control asparagus beetle infestations.

Ready to grow your asparagus and enjoy homegrown harvests for years to come? Visit our website to explore our wide range of gardening supplies, from organic compost to high-quality asparagus crowns. Get started today and transform your garden into a thriving oasis.