Asparagus in Zone 3B — Mountain West

Asparagus is a true taste of spring, and well worth the wait for us high-altitude gardeners. The flavor is unbeatable fresh from the garden, and it's a perennial that will keep producing for years. Plus, those cool nights even in summer seem to make asparagus taste even sweeter.

Our short growing season here in the Mountain West (about 108 days) means you need to be smart about timing, but asparagus is surprisingly hardy. With a little planning, you can enjoy fresh spears for years to come, despite our alkaline soil and intense UV.

Transplant your asparagus crowns outdoors from late May through early June, once the danger of hard frost has passed. Before planting, be sure to harden off your asparagus crowns by gradually exposing them to the outdoor elements for about a week. This helps them adjust to the intense sun and cooler nights.

Space the crowns about 18-24 inches apart in a well-prepared bed. Keep an eye out for late-season frosts, which can still happen even in early June. Be ready to cover your young plants if temperatures dip unexpectedly. Remember to start with 1-year-old crowns for the best chance of success; growing from seed takes patience!

Asparagus needs moderate watering, especially when it's getting established. Once your asparagus is established (after about two years), it becomes fairly drought-tolerant thanks to its deep roots.

During our dry Mountain West summers, check the soil moisture regularly. Stick your finger about two inches deep; if it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the ferns, which helps prevent fungal issues in our low-humidity environment.

Pay attention to your plants. If the ferns start to yellow and droop, that's a sign of underwatering. If the ferns are yellowing and the soil is constantly soggy, you might be overwatering. Mulching around your asparagus with straw or wood chips can help retain moisture and regulate soil temperature during our intense summer days.

Asparagus pruning is minimal. The most important thing is to let the ferns grow and flourish all summer long. These ferns are feeding the crown, ensuring a good harvest next year.

In late fall, after the first frost around early September has killed back the ferns, or in early spring before new growth emerges, cut the dead ferns back to the ground. Do not harvest for more than 8 weeks each season to keep your plants healthy and productive long-term.

Your first harvest will likely be late May through late September, but remember that it takes about two years from transplanting crowns to get your first harvest. Be patient!

Harvest spears when they are 6-8 inches tall and have tight, closed tips. Snap or cut the spears off at ground level. Once the spears start thinning to about the width of a pencil, stop harvesting for the season and let the remaining spears fern out to replenish the plant's energy.

Continuous harvesting encourages more spears to emerge, so check your plants every day or two during peak season. As the season winds down and the first frost approaches, it's time to let the plants focus on storing energy for next year.

Here are a few common asparagus problems we face in the Mountain West:

Asparagus Beetle

• What it looks like: Small, metallic blue-black beetles and their larvae feeding on spears and ferns.
• What causes it: These beetles thrive in our sunny conditions.
• How to fix/prevent it: Handpick beetles and larvae. Encourage beneficial insects like ladybugs. Insecticidal soap can be used as a last resort.

Crown Rot

• What it looks like: Yellowing ferns, stunted growth, and mushy, rotting crowns.
• What causes it: Poor drainage and overly wet soil. Our alkaline soil can sometimes contribute to drainage issues.
• How to fix/prevent it: Ensure good drainage when planting. Avoid overwatering. Amend heavy clay soils with compost.

Thin Spears

• What it looks like: Spears that are much thinner than usual, often pencil-thin or smaller.
• What causes it: Over-harvesting and not allowing the plants to replenish their energy reserves.
• How to fix/prevent it: Limit your harvest to 6-8 weeks per season. Ensure plants receive adequate water and nutrients. Let plenty of spears fern out to support the crown.

Mountain West Specific Challenges: Our intense UV can stress plants, making them more susceptible to pests and diseases. Our dry climate means consistent watering is crucial, but we also need to be careful to avoid overwatering, especially in heavy soils.

Companion planting can really help your asparagus thrive. Tomatoes make great companions because they deter asparagus beetles. Parsley is another good choice, attracting beneficial insects that prey on asparagus pests. Basil also repels asparagus beetles and improves the overall health of your asparagus patch.

Avoid planting asparagus near onions or garlic. These plants can inhibit asparagus growth. By choosing the right companions, you can create a healthier and more productive asparagus bed, even in our challenging Mountain West climate.