Asparagus in Zone 7B — Mid-Atlantic

Asparagus is a true treat in the Mid-Atlantic garden. The taste of freshly harvested spears, lightly grilled with a bit of olive oil, is far superior to anything you'll find at the grocery store. Plus, asparagus is a perennial, so you’ll get to enjoy it for years to come.

Our four seasons here in the Mid-Atlantic mean that asparagus enjoys both a dormant period and a long growing season. While we deal with humid summers and variable spring weather, the 214-day growing season gives asparagus plenty of time to thrive once it's established. With a little attention to timing, you'll be harvesting your own delicious spears.

Early April is the ideal time to transplant asparagus crowns here in the Mid-Atlantic. Before planting, be sure to harden off your 1-year-old crowns by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the temperature swings that are common this time of year.

When transplanting, space your asparagus crowns 18-24 inches apart in a well-prepared bed. Keep an eye on the forecast; we sometimes get a late frost in early April, so be ready to cover your new plants if needed.

Asparagus needs moderate watering, especially during its first two years. Once established, its deep roots make it fairly drought-tolerant, which is helpful during our occasionally dry spells in late summer. However, consistent moisture is key for optimal spear production.

During the spring and fall, when rainfall is usually consistent, aim for about 1 inch of water per week. Use the finger test: stick your finger about 2 inches into the soil near the base of the plants. If it feels dry, it's time to water. In the heat of our humid summers, you might need to increase watering to 1.5 inches per week. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid climate.

Signs of underwatering include yellowing or wilting ferns, while overwatering can lead to root rot. A good layer of mulch, like shredded leaves or straw, will help retain moisture and suppress weeds.

Asparagus pruning is minimal, but important. Throughout the summer, let the ferns grow tall and bushy. They're busy photosynthesizing and storing energy in the crown for next year's spears.

In late fall or early spring, after the ferns have died back and turned brown, cut them down to the ground. This helps prevent disease and keeps the bed tidy. Remember not to harvest for more than 8 weeks each season, to allow the plants to rebuild their energy reserves.

You can expect your first harvest of asparagus spears in late March through mid November, about two years after transplanting the crowns. Look for spears that are 6-8 inches tall with tight, closed tips.

To harvest, snap the spears off at ground level. Be careful not to damage the surrounding spears or the crown. Continue harvesting regularly, every few days, until the spears start to become thin, about the width of a pencil.

Once the spears thin out, stop harvesting and let the remaining spears fern out. This allows the plant to store energy for next year's crop. As the first frost approaches in early November, any remaining spears should be left to develop into ferns.

Asparagus can have a few problems in the Mid-Atlantic garden.

Asparagus Beetle

• What it looks like: Small, elongated beetles (often striped or spotted) and their larvae feeding on spears and ferns, causing damage and discoloration.
• What causes it: These beetles are attracted to asparagus plants and thrive in our moderate-to-hot summers.
• How to fix/prevent it: Handpick beetles and larvae when you see them. Encourage beneficial insects like ladybugs, which prey on asparagus beetles. Insecticidal soap can also be effective.

Crown Rot

• What it looks like: Yellowing or wilting ferns, stunted growth, and mushy, decaying roots.
• What causes it: Poorly drained soil and excessive moisture, especially during our periods of heavy rainfall. Clay soil, common in the Mid-Atlantic, exacerbates this problem.
• How to fix/prevent it: Plant asparagus in well-draining soil or raised beds. Avoid overwatering. Improve drainage by amending the soil with compost and other organic matter.

Thin Spears

• What it looks like: Spears that are significantly thinner than usual, often pencil-thin or smaller.
• What causes it: Over-harvesting asparagus, which depletes the plant's energy reserves.
• How to fix/prevent it: Limit your harvest to 8 weeks per season. Allow the plants to fern out and replenish their energy stores. Ensure the plants receive adequate water and nutrients.

Mid-Atlantic Specific Challenges: Our humid summers can create favorable conditions for fungal diseases, so good air circulation and well-drained soil are crucial. Deer pressure can also be a concern, so consider fencing or using deer repellent.

Companion planting can benefit your asparagus in the Mid-Atlantic garden. Tomatoes make good companions because they deter asparagus beetles. Parsley attracts beneficial insects that prey on asparagus pests. Basil can also help repel asparagus beetles and other unwanted bugs.

Avoid planting asparagus near onions or garlic. These plants are allelopathic to asparagus, meaning they release chemicals that can inhibit its growth.