How to Plant, Grow, and Care for White Asparagus

If you’ve ever tasted white asparagus spears, you probably know why they’ve become a culinary craze. They have a delicate, nutty flavor and refreshing texture. Like green asparagus, they’re also packed with nutrients. 

What you may not know is that these unique looking vegetables are from the same plant as their green lookalikes. In fact, you can grow white asparagus in your garden by changing one simple process. 

All asparagus are dioecious plants. This means that each plant has either male and female flowers. The white varieties you find at the grocery store and market are most likely the male spears due to their productivity. 

Characteristics

In the garden, white asparagus will eventually turn green once exposed to sunlight. Male spears will grow to be larger than the female spears. When they mature, they produce beautiful bell-shaped flowers ranging from yellow to white. 

There are tons of varieties and hybrids to choose from. You can produce delicious and tender white spears from any type of asparagus. Some are more disease resistant and flavorful than others. Below are some common varieties to choose from. 

‘Mary Washington’

This heirloom variety produces large female spears with tons of flavor. If left exposed to the sunlight, the spears will be dark green. Cover them with soil as they grow and they will stay white. 

‘Millennium’

This is a cold-hardy variety that grows great in many gardens throughout the U.S. It has a rich flavor and is very disease-resistant. 

‘Jersey Giant’

This is a large and flavorful variety with very high yields. It usually produces male plants. This is one of the most disease-resistant varieties you can grow. 

Native Area

These perennial vegetables evolved in Europe, North Africa, Western Asia, and the Middle East. Asparagus developed a deep taproot system to survive various climates. It was first cultivated around 2,000 years ago in ancient Greece, Egypt, and the Mediterranean basin. The ancient Greeks thought it was an aphrodisiac while the Romans used it as a main course for their legions. 

In its native habitat, it flourished in sandy soils and mountainous terrain. In places such as the Middle East, it evolved in arid soils and developed a tolerance to drought conditions. 

White asparagus was first cultivated in Europe in the 17th century. It was a popular dish in French aristocratic households. Today, it usually costs more than green asparagus. Chefs and foodies tend to agree that its sweeter and richer taste and delicate texture are worth the hype. 

Planting

Asparagus is a perennial that grows best in well-drained soil and full sun. It should go in the ground in early spring. Once it establishes itself in the soil, it will give you a bountiful harvest for 20 years or more. 

The location you plant your seedlings or crowns is very important. You want well-drained soil with plenty of nutrients and direct sunlight. It should be deep and porous, with no barriers for the taproots. 

Personally, I’ve always grown my plants in tall raised beds like this one. They bring the plants closer to eye level. When you’re producing white spears, it makes it easier to keep an eye on the spear as they grow. 

Growing From Crowns

Crowns are a better starting point for first-time white asparagus growers. You can plant them immediately, and they can be easier to find at your local nursery. 

Before planting your crowns, soak them in water or compost tea for 30 minutes to an hour to hydrate them. Then, lay them down on 6 inch trenches of soil. Space them out at least 12 inches to 18 inches apart. Spread out their roots to cover the maximum surface area per plant. 

After laying the crowns in the trenches, make sure all the tiny buds are pointed upward. Cover them with 3 inches of soil and water them until the soil is moist. 

How to Grow

White asparagus is relatively easy to grow, as long as you have the right location, lots of light, and enough soil to keep the spears covered. As the spears get larger, the trick is to keep covering them with soil so they never see the sun. Harvest them just before the heads of the spears appear to open up. 

Alternatively, you can cover your plants with black plastic or cloth while their spears grow. This will also block the sunlight and keep the spears white and tender. 

Light

This perennial vegetable needs plenty of sunlight. Plant them in an area with at least 6 to 8 hours of direct sunlight. 

For white spears, you’ll still need the sunlight for the plants to grow. Leave a few spears to grow above the soil after harvesting. 

Water

These perennials need plenty of water as they establish themselves in your garden bed. Once they grow their taproots, they can handle long periods of drought. 

Keep their soil moist, especially when they’re young. Aim for an inch or two a week. Give your plants a long soak every two weeks. 

To conserve water, use mulch around your plants. This will help conserve the water in the soil and give your young plants enough moisture to grow. Use one that allows water to penetrate the mulch layer, like straw.

Soil

Use well-drained soil that’s full of rich organic material. Before planting, amend your soil with plenty of organic compost and worm castings. This will ensure enough NPK (nitrogen, phosphorus, and potassium) nutrients get into your soil. 

Temperature and Humidity

These popular perennial vegetables will grow in zones 2 through 9. It’s incredibly resilient to many climates. Before planting, make sure the soil is above 50°F (10°C). Ideal planting temperatures will be closer to 60°F (16°C).

The plant evolved in regions with low humidity. Because of this, your plants prefer lower humidity. You may have trouble growing it in tropical regions like southern Florida. 

Fertilizing

Your plants need plenty of organic fertilizer, compost, and manure to produce bountiful harvests and crispy asparagus. Every fall and spring, add a little slow-release fertilizer. An organic plant food lower in nitrogen and higher in phosphorus and potassium is ideal. 

When you fertilize, carefully remove the mulch and add the fertilizer around the roots and water. Keep the fertilizer away from the plant tissue to avoid fertilizer burn. 

Maintenance

Use disinfected pruners to harvest the spears in late spring or early summer, two years after planting your crowns. Let a few grow into mature flowering stalks. When your plants turn brown, they’re storing energy in their roots for their winter dormancy period. 

During this time, use your clean clippers to remove the brown stalks and compost them. Add another layer of mulch and fertilizer. After winter, just make sure your garden bed is weed free and you should have another bountiful harvest the following year. 

Propagation

You can propagate your plants from division or by growing seeds. Each method is easy. Remember that you’ll only get harvests from plants that are over two years old. 

Seeds

Start your seeds indoors during the winter, usually around January or February. Soak them in water for a day to let them hydrate before planting. 

They need at least three weeks to germinate. Once they germinate, be patient and let them develop for another 12 to 14 weeks before transplanting. 

Once they’re over three inches tall, they should be ready for planting outside. You want to time them to be around this height just before the last frost of the year. Once the soil is close to 60°F (16°C), it’s time to get them outside. 

Prepare your soil with plenty of nutrients. Make sure it’s well draining and porous to allow the long taproot plenty of room to develop. 

Division

Divide mature plants once they outgrow their beds. This is an easy way to propagate your asparagus to plant in other parts of your garden or give away as crowns. 

In the fall, dig up the roots carefully with a clean shovel or spade. Simply cut the root ball with clean scissors. Spread the root ball out with your hands and separate it from the parent plant. You can transplant the divided plant immediately or store it away in a cool, dark place until planting the following spring. 

Harvesting 

During the first year after planting your seeds, your plants are developing their root systems. You won’t get any spears during this phase. After the second year, you’ll start to see some spears forming above the soil. Leave them be and let them grow to maturity. During the third year, start harvesting about half your spears. 

If you’re growing your plants from crowns, it’s best to wait until the second year to harvest them. You want to give the plants enough time to establish their roots and adjust to the soil. 

To produce white asparagus, wait until the spears are just about to break the surface. Each day, cover them with a little soil. Return each day and keep covering them a little more. Once they’re over 6 inches tall, they should be ready for harvesting. At this point, they should be creamy white colored and tender. 

Storage

Treat white asparagus like green asparagus. They’re incredibly delicious, eaten fresh right after harvesting. You can cut the ends off and place them in a jar of water to prolong their shelf life. 

You can also dip them in hot water and freeze them to preserve them for longer. Boil them for a minute and immediately drop them into ice water to shock them. After about a minute, dry them out, cover them in plastic wrap, and freeze them. They’ll last for months until you’re ready to heat them and serve. 

Common Problems

White asparagus doesn’t have too many problems. The biggest problems involve common garden pests and a few pests that target asparagus plants. The best defense is keeping a thriving ecosystem of beneficial insects in your garden. 

Pests

Pests can pose a risk to your white asparagus, especially as the spears grow under the soil. In my garden, cutworms and aphids were the worst. Cutworms attack the young spears, especially towards the heads. 

For other gardeners, nothing’s worse than the asparagus beetle. This critter can wipe out entire harvests before you even see them. Asparagus miners and thrips can also be problematic. 

Control these pests by creating a healthy ecosystem of beneficial insects in your garden. Encourage lady beetles, wasps, and microscopic nematodes to live in your garden. They will pray on the pests and keep your plants healthy. 

You can remove debris in your garden to control worms and beetles. Proper tilling before planting your spears can reduce their numbers. Try leaving a bare area of soil around your asparagus bed to deter cutworms. Remove ferns once they brown to prevent asparagus beetles from overwintering.

Diseases

The most harmful disease for your plants is fusarium root rot. This disease develops over time in the soil. There’s no cure, and the best prevention method is planting disease-resistant varieties that can withstand infections. 

Most gardeners will encounter asparagus rust at least once. This common disease is caused by the fungi Puccinia asparagi. When your plants become infected, their foliage develops orange-yellow spots that turn into black infections. After removing infected leaves, treat them with sulfur dust. 

Frequently Asked Questions