Asparagus in Zone 7A — Mountain West

Asparagus is a true delicacy worth the effort in our Mountain gardens. The flavor of freshly harvested asparagus, kissed by our intense sun and cooled by our cool nights, is simply unmatched. Plus, it's incredibly versatile in the kitchen and offers the unique satisfaction of harvesting your own food for years to come.

High altitude gardening in Zone 7A comes with its challenges: intense UV, alkaline soil, and a short 173-day growing season. But with careful timing and a little extra attention, you can absolutely enjoy homegrown asparagus. The cool nights we experience even in summer are actually beneficial for flavor development.

Transplant your asparagus crowns outdoors from mid to late April, after the last threat of frost has passed. Before planting, be sure to harden off your 1-year-old crowns by gradually exposing them to the outdoor conditions for about a week. This helps them adjust to our intense sun and fluctuating temperatures.

Space the crowns 18-24 inches apart in well-draining soil. Keep an eye on the weather forecast – a late-season cold snap or even hail can damage young transplants, so be prepared to cover them if necessary. Remember, buying crowns is the way to go; growing from seed in our short season means waiting 3+ years for your first harvest.

Established asparagus is surprisingly drought-tolerant, thanks to its deep roots, but getting it established requires consistent watering. During the first two years, aim to keep the soil consistently moist, but not waterlogged. Once established, moderate watering is key.

In our dry Mountain climate, a good rule of thumb is to water deeply about once a week, providing about 1 inch of water. Use the finger test – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Focus on watering at the base of the plant to avoid water loss from evaporation in our low humidity.

Signs of underwatering include wilting or yellowing ferns. Overwatering, on the other hand, can lead to crown rot. A layer of mulch, like straw or wood chips, can help retain moisture in our dry climate and regulate soil temperature, but avoid piling it directly against the crown to prevent rot.

Asparagus pruning is fairly minimal. During the growing season, let the ferns grow freely. These ferns are essential for photosynthesis, feeding the crown and ensuring a bountiful harvest next year.

In late fall or early spring, after the ferns have died back and turned brown, you can cut them down to ground level. This helps remove any potential overwintering pests or diseases. Just remember to not harvest for more than 8 weeks to ensure the plant stays healthy.

Your first asparagus harvest will be about two years after transplanting. In our Zone 7A Mountain climate, you can expect to start harvesting from mid-April through late October. Look for spears that are 6-8 inches tall with tight, closed tips.

To harvest, snap the spear off at ground level, being careful not to damage the surrounding crown. Continue harvesting regularly to encourage more spear production. Stop harvesting when the spears start to become thin, about the diameter of a pencil. At that point, let the remaining spears fern out to replenish the plant's energy reserves before our first frosts arrive in early October.

Asparagus can encounter a few problems in our Mountain gardens. Here are three common issues and how to address them:

Asparagus Beetle

• What it looks like: Small, metallic blue or orange beetles and their larvae feeding on spears and ferns.
• What causes it: These beetles are attracted to asparagus plants and can quickly defoliate them.
• How to fix/prevent it: Handpick beetles and larvae. Encourage beneficial insects like ladybugs. In severe cases, use insecticidal soap, being mindful of pollinators.

Crown Rot from Poor Drainage

• What it looks like: Yellowing or wilting ferns, stunted growth, and a mushy, rotting crown.
• What causes it: Poorly draining soil leads to fungal diseases that attack the crown.
• How to fix/prevent it: Ensure well-draining soil. Amend heavy clay soils with compost. Avoid overwatering. Remove and destroy infected plants to prevent spread.

Thin Spears from Over-Harvesting

• What it looks like: Spears that are significantly thinner than usual, often pencil-thin.
• What causes it: Harvesting too many spears or harvesting for too long depletes the plant's energy reserves.
• How to fix/prevent it: Limit your harvest to 8 weeks per season. Allow plenty of ferns to grow and replenish the crown's energy.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity generally reduce disease pressure on asparagus. However, our dry rainfall means consistent watering is crucial, especially during establishment. Alkaline soil can also be an issue, so amend with compost to improve pH.

Companion planting can benefit your asparagus patch. Tomatoes, parsley, and basil are excellent companions. Tomatoes provide shade during our intense sun, protecting the asparagus from excessive UV. Parsley attracts beneficial insects that prey on asparagus pests. Basil also repels asparagus beetles.

Avoid planting asparagus near onions or garlic. These alliums can inhibit asparagus growth, potentially stunting their development in our already short growing season.