How To Grow White Asparagus

Dreaming of growing your own white asparagus? By simply hilling up soil over the spears, you block photosynthesis and create that prized, delicate flavor.

How to Grow White Asparagus: The Blanching Technique

Selecting Male-Only Hybrid Varieties for Higher Yields

To grow white asparagus successfully, start by choosing male-only hybrid varieties like ‘Jersey Giant’ or ‘Guelph Millennium’. Male plants are preferred because they don’t waste energy producing seeds, which means you’ll get higher yields and thicker spears.

Female plants, on the other hand, drop seeds that can overcrowd your bed and reduce overall productivity. Look for certified disease-free crowns from a reputable nursery to ensure healthy growth. These hybrids are bred for vigor and resistance to common issues like fusarium wilt, making your job easier.

When you plant male-only varieties, you’re setting yourself up for a long-term harvest that can last 15 years or more. Invest in quality crowns upfront—it’s a small effort that pays off with bountiful, tender white spears season after season.

Avoid open-pollinated varieties if you want maximum production; stick to these high-performing hybrids for the best results.

Preparing a Deep Trench for Planting

White asparagus needs deep trenches to grow properly, so dig a trench about 12-18 inches deep and wide enough to accommodate the crowns. This depth allows you to mound soil over the spears as they grow, blocking sunlight.

Place the crowns at the bottom, spacing them 12-18 inches apart with their roots spread out. Cover them with 2-3 inches of soil initially, then gradually fill the trench as the spears emerge. This mounding process is crucial for blanching, ensuring the spears stay pale and tender.

Ensure your soil is well-draining and rich in organic matter, like compost, to support healthy growth. A deep trench also makes it easier to harvest the spears without damaging the crowns.

Take your time preparing the bed—proper setup now means less work later and a more productive asparagus patch for years to come.

Excluding Light to Prevent Photosynthesis

The secret to white asparagus is excluding light to prevent photosynthesis, which keeps the spears white and sweet. As spears emerge, cover them with soil or a blanching collar to block sunlight completely. If using soil, mound it 6-8 inches above the crown, ensuring no light penetrates.

Alternatively, use black plastic or specialized collars for easier harvesting. Check regularly to ensure no cracks let light in, as even brief exposure turns spears green. This process is labor-intensive but worth it for the delicate, mild flavor unique to white asparagus.

Harvest when spears reach 6-10 inches tall by gently cutting them below the soil surface. After harvest, remove covers to let the ferns grow and recharge the plant for next season. Consistency is key—keep spears covered throughout the growing season for the best results.

With patience and care, you’ll enjoy a gourmet harvest from your own backyard.

Preparing the Ideal Soil and Location

Testing Soil pH and Nutrient Levels

To get those delicious white spears, you need to start underground with a solid foundation. Before you even think about planting crowns, grab a soil test kit from your local garden center.

White asparagus is a heavy feeder and thrives in soil that is slightly acidic to neutral, specifically aiming for a pH level between 6.0 and 7.0.

If your soil is too sour or too sweet, the plants won’t be able to absorb the nutrients they need to produce those thick, tasty spears. The test results will also tell you if you are lacking in essential minerals like phosphorus and potassium, which are crucial for root development.

Based on what you find, mix in plenty of well-rotted manure or a balanced fertilizer to amend the soil. Taking this extra step now saves you a lot of headaches later and ensures your bed remains productive for over a decade.

Ensuring Loose, Sandy Soil for Straight Spears

Texture is everything when you are trying to grow perfect white asparagus because the spears develop entirely underground. You want to aim for a soil structure that is incredibly loose and friable, ideally a sandy loam. Why does this matter so much?

If your soil is heavy with clay or full of compacted clumps, the emerging spears will hit resistance and grow crooked or bent. Since white asparagus relies on being deprived of light, you will be mounding soil over the plants as they grow, known as hilling up.

You need that mound to stay fluffy and airy so the spears can shoot straight up without fighting for space. If your native ground is heavy, don’t panic. Just mix in generous amounts of coarse sand, compost, and organic matter to break up the density.

This creates a drainage-friendly environment that prevents rot and makes harvesting those pale, tender shoots much easier when the time comes.

Choosing a Site with Full Sun Exposure

While the actual white spears are kept in the dark, the plants themselves are sun worshipers. You need to pick a spot in your yard that receives full sun exposure for at least six to eight hours a day.

Asparagus plants need this intense solar energy to fuel the ferny foliage that emerges after the harvest season. Those ferns are the workhorses of the plant, soaking up sunlight and sending carbohydrates down into the root system.

This energy storage is what powers next year’s harvest, so skimping on light now will result in spindly spears later. Avoid planting near large trees or shrubs that will cast shade or compete for water and nutrients.

Remember, an asparagus bed is a long-term commitment that can last fifteen years or more, so choose a permanent location where the plants can bask in the light undisturbed. A sunny, open field or raised bed corner is the perfect real estate for a thriving crop.

Step-by-Step Guide to Planting Asparagus Crowns

Determining the Best Time to Plant

To grow white asparagus, timing is everything. The best time to plant asparagus crowns is in early spring, as soon as the soil can be worked, but before new shoots emerge. This gives the roots a head start to establish before the growing season kicks in.

If you live in a colder region, wait until the frost danger has passed. For warmer climates, late winter planting works well too. Avoid planting in summer or fall, as the roots may not have enough time to settle before winter.

White asparagus thrives in cooler temperatures, so early planting ensures the crowns develop strong roots without heat stress. Remember, the goal is to give the crowns a dormant period before active growth begins, setting the stage for a bountiful harvest in years to come.

Correct Spacing and Depth for Root Systems

Proper spacing and depth are critical for healthy white asparagus. Dig trenches 12-18 inches deep and 6-8 inches wide, spacing them 3-4 feet apart to allow room for the ferns to grow.

Place the crowns in the trenches with the buds facing upward, ensuring they’re spaced 12-18 inches apart within the row. Cover the crowns with 2-3 inches of soil initially, then gradually fill the trench as the shoots grow.

This method encourages the spears to grow vertically, essential for blanching to achieve white asparagus. Avoid planting too deep, as this can delay emergence, or too shallow, risking exposure to light, which turns spears green.

The trench method also makes it easier to mound soil around the spears later for blanching. Consistency is key—ensure uniform spacing and depth for even growth and easier maintenance.

Initial Watering Setup for Root Establishment

Watering immediately after planting is vital for root establishment. Give the crowns a deep, thorough watering to settle the soil and remove air pockets around the roots. For the first few weeks, keep the soil consistently moist but not waterlogged.

A good rule of thumb is to provide 1 inch of water per week, either through rainfall or manual watering. Mulching around the plants helps retain moisture and suppress weeds, reducing competition for nutrients. As the spears grow, reduce watering slightly, but don’t let the soil dry out completely.

White asparagus requires steady moisture to develop tender, flavorful spears. Avoid overhead watering, as it can promote fungal diseases; instead, water at the base of the plants. Proper hydration now ensures the roots develop strong, setting the foundation for a long-lasting, productive asparagus bed.

Mastering the Mounding Process for White Spears

Building Soil Ridges Over the Crowns

To get those prized white spears, you need to block sunlight effectively, which starts with creating tall soil ridges.

Once your spring spears begin poking through the surface, use a hoe to pull loose soil up against the row, forming a mound that should stand at least 10 to 12 inches high. This height is crucial because any exposure to sunlight will turn the spears green and bitter.

Ensure the ridge is wide enough at the base to provide stability but steep enough to cover the growing tips completely. As the spears elongate underground, you may need to add more soil to maintain the cover, preventing them from breaking through too early.

This process, known as blanching, forces the asparagus to grow without chlorophyll, resulting in that delicate, sweet flavor unique to white varieties. Keep the mound smooth and tight to discourage weeds and retain moisture.

Using Plastic Covers or Cloches vs. Soil Mounding

While traditional mounding uses loose soil, many modern gardeners prefer black plastic sheeting to save labor and improve weed control.

You can lay this material directly over the row before spears emerge or drape it over low hoops; the dark color blocks light effectively, simulating the mounding effect without the heavy digging. However, soil mounding often provides better insulation against sudden temperature drops and retains moisture more naturally than plastic.

If you choose cloches, ensure they are opaque, as clear ones will let light in and ruin the blanching process. Soil remains the gold standard for maximum flavor, but plastic is an excellent shortcut if you have heavy clay soil that is difficult to hoe into high ridges.

Ultimately, choose the method that fits your physical capabilities and garden setup, but remember that keeping light completely out is the number one priority.

Monitoring Spear Growth Under the Mound

Since you cannot see the spears growing, you must rely on touch and timing to harvest at the perfect stage. Gently press your hand against the soil ridge to feel for the hard tips pushing upwards; they are ready when the ridge cracks or swells slightly.

To harvest, use a specialized asparagus knife to carefully cut the spear about an inch below the soil surface, taking care not to damage neighboring spears or the crown. After removing the spear, immediately close the opening with soil to maintain darkness around the remaining stalks.

This step is vital because any light entering the mound will compromise the quality of the next harvest. Check your ridges every couple of days during the peak season, as white asparagus grows incredibly fast when warmth builds up in the soil mound.

Essential Maintenance and Fertilization

Applying Fertilizer in Early Spring

In early spring, before the asparagus spears emerge, it’s crucial to feed your plants with a balanced fertilizer to support healthy growth. Use a 10-10-10 or 5-10-10 fertilizer, applying it about 2-3 inches away from the crowns to avoid burning the roots.

Work the fertilizer gently into the soil with a hand rake, then water thoroughly to help nutrients absorb. This early boost ensures strong, tender white spears later in the season. If your soil is sandy, consider adding compost or well-rotted manure to improve nutrient retention.

Avoid over-fertilizing, as too much nitrogen can lead to fibrous spears. A single application in spring is usually sufficient, but you can top up with a light layer of organic mulch to slowly release additional nutrients as the season progresses.

Managing Weeds Without Damaging Roots

Weeds compete with asparagus for nutrients and water, so keeping them in check is vital. Since asparagus roots are shallow, avoid deep hoeing, which can disturb the crowns. Instead, use hand weeding or carefully apply a pre-emergent herbicide in early spring to prevent weed seeds from germinating.

A thick layer of mulch, like straw or shredded leaves, can also suppress weeds while retaining soil moisture. If weeds do appear, pull them gently by hand, ensuring you don’t disrupt the developing spears.

For persistent weeds, spot-treat with a vinegar-based weed killer, but avoid spraying directly on the asparagus plants. Regular maintenance is key—check the bed weekly and remove weeds before they establish deep roots. This minimal disturbance approach keeps your white asparagus thriving without unnecessary stress.

Watering Requirements for Maximum Yield

White asparagus needs consistent moisture to produce tender, flavorful spears. Water deeply once a week, providing 1-1.5 inches of water, especially during dry spells. A soaker hose or drip irrigation system works best, as it delivers water directly to the roots without wetting the foliage, reducing disease risk.

Avoid shallow, frequent watering, which encourages weak root growth. Instead, focus on longer, less frequent sessions to encourage deep roots. Mulching around the plants helps retain moisture and reduces water evaporation.

During peak growing season, monitor soil moisture by sticking your finger 2 inches into the soil—if it feels dry, it’s time to water. Overwatering can lead to root rot, so ensure the soil drains well. Consistent, even moisture is the secret to a bountiful harvest of high-quality white asparagus.

Harvesting White Asparagus at the Right Time

Recognizing Signs of Maturity

Knowing when your white asparagus is ready to pick is all about timing and observation. White asparagus grows underground, so you won’t see the spears turning green like the purple or green varieties. Instead, you’ll notice small cracks appearing on the soil surface above the growing spear.

This is your cue that the asparagus is pushing upward and is likely ready for harvest. Gently brush away the dirt to check the spear’s tip—it should be tightly closed and firm.

If the tip starts to open or feather out, it’s past its prime and will be tough to eat. For the best flavor and texture, aim to harvest spears when they are about 6 to 8 inches long and as thick as your thumb.

Patience is key, as harvesting too early can weaken the plant, while waiting too long results in woody, fibrous stalks.

Techniques for Cutting Spears Underground

Harvesting white asparagus requires a gentle touch to avoid damaging the crown. Start by carefully using a specialized asparagus knife or a long, slender knife to loosen the soil around the spear. Dig down about 6 to 8 inches deep until you reach the base of the spear.

Make a clean, diagonal cut just below the soil surface, ensuring you don’t slice into the crown or neighboring buds. This method encourages new growth and keeps the plant healthy. After cutting, immediately cover the hole with soil to protect the remaining crown from light and maintain the white color.

Avoid twisting or pulling the spears, as this can harm the root system. Remember, white asparagus is more delicate than its green counterpart, so handle it carefully to prevent bruising. Proper harvesting techniques ensure a bountiful crop for years to come.

Stopping the Harvest to Allow Fern Growth

It’s tempting to keep harvesting, but stopping at the right time is crucial for long-term plant health. Generally, you should stop harvesting after 6 to 8 weeks or when the spear diameter becomes smaller than a pencil. This signals the plant needs to redirect energy into root and fern development.

Allowing the ferns to grow tall and feathery helps the plant store nutrients for the next season. Don’t cut back the ferns until they turn yellow or brown in the fall, as this is when they’re most productive. Neglecting this step can weaken the plant and reduce future yields.

By letting the ferns thrive, you’re investing in a healthier, more robust asparagus bed for years to come. Remember, white asparagus is a perennial crop, so giving it time to recover ensures delicious harvests season after season.

Winter Care and Long-Term Bed Management

Why Your Watercress Leaves Are Turning Yellow

If you notice your watercress leaves starting to yellow, it usually signals a nutrient deficiency, specifically a lack of nitrogen. Since watercress is a heavy feeder, growing it in plain water without fertilizer will quickly deplete the resources it needs to produce vibrant green foliage.

To fix this, switch to a balanced liquid fertilizer diluted to half strength every two weeks. Additionally, check the water quality; if you are using tap water with high chlorine, it might be shocking the roots. Let the water sit out overnight before using it or switch to filtered water.

Finally, ensure the plant isn’t sitting in stagnant water, as this can lead to root rot which manifests as yellowing leaves. Refresh the water regularly to keep oxygen levels high and prevent algae buildup.

With these adjustments, your plant should return to its healthy, deep green color within a week or two.

Dealing with Leggy or Weak Growth

Leggy or weak growth is a telltale sign that your indoor watercress is desperate for more light intensity. When plants stretch out, they are literally reaching for the nearest light source, which results in spindly stems that break easily.

To solve this, move your container to a brighter spot, preferably a south-facing window where it can get at least six hours of sunlight daily. If natural light is scarce in your home, consider supplementing with a simple LED grow light placed a few inches above the plant.

You should also rotate the pot every few days to ensure the plant grows evenly rather than leaning heavily in one direction. Trimming the top tips occasionally can also encourage the plant to become bushier and stronger rather than just growing tall and thin.

Consistent lighting is the secret to sturdy, compact growth that tastes crisp and fresh.

Reviving Wilted or Dying Plants

Finding your watercress wilted can be alarming, but the solution is often quite simple. This aquatic plant hates drying out, so inconsistent watering is likely the culprit. If the soil or growing medium feels dry, give the plant a thorough soak immediately.

It is best to grow watercress in a tray or saucer filled with water so the roots can stay constantly moist. Another common issue is heat stress; watercress prefers cooler temperatures between 50 and 70 degrees Fahrenheit.

Keep it away from hot radiators or drafts which can dry out the foliage rapidly. If the roots look slimy or smell bad, rinse them off gently and replace the water entirely to prevent bacterial issues. By maintaining constant moisture and cooler temperatures, your plant should perk back up.

Remember, this plant thrives on wet conditions, so never let the water level drop too low.

Frequently Asked Questions

Conclusion

Successfully growing white asparagus demands patience and specific techniques, particularly blanching to exclude light. Although it takes time for the crowns to establish, the wait is rewarded with a delicious, gourmet harvest.