Asparagus in Zone 3A — Mountain West

Asparagus is a true taste of spring, and even with our short growing season here in the Mountain West, it's worth the effort. The spears taste incredible fresh, far better than anything you'll find at the grocery store, and the perennial nature of asparagus means you'll have a reliable harvest year after year. Plus, the cool nights even in summer really concentrate the sugars, giving them an exceptional flavor.

Our high altitude and short season can be challenging, but with careful timing, asparagus thrives here. Remember, we only have around 96 days between frosts, so getting your plants off to a strong start is key. Once established, asparagus is surprisingly resilient in our Mountain climate.

Transplant your asparagus crowns outdoors around early June, after the last expected frost. Before planting, be sure to harden off your crowns by gradually exposing them to the outdoors for about a week. This helps them adjust to our intense sun and fluctuating temperatures.

Space your crowns 18-24 inches apart in rows. In the Mountain West, we sometimes get a late-season hail storm even in June, so consider using row covers for the first few weeks to protect your young plants. Remember to purchase 1-year-old crowns for best results.

Established asparagus is fairly drought-tolerant, but consistent watering is crucial, especially in our dry Mountain climate. During the peak of summer, give your asparagus about 1 inch of water per week. Use the "finger test" – if the soil is dry to a depth of 2 inches, it's time to water.

Water deeply at the base of the plants to encourage strong root growth. Overhead watering isn't ideal in our region, as it can encourage fungal diseases, though our low humidity usually keeps that at bay. Aim to water in the mornings so the foliage has time to dry out before our cool nights set in.

Signs of underwatering include yellowing or wilting spears. Overwatering, on the other hand, can lead to root rot. A good layer of organic mulch, like compost or wood chips, will help retain moisture and regulate soil temperature, both of which are important in our variable Mountain climate.

Asparagus requires minimal pruning. Throughout the summer, let the ferns grow freely. These ferns are vital for photosynthesis, providing the energy the plant needs to produce spears next year.

In late fall or early spring, after the ferns have died back and turned brown, cut them down to the ground. Be careful not to damage the crowns while doing so. Also, remember to limit your harvest to no more than 8 weeks per season to prevent weakening the plant.

You can expect your first harvest of asparagus starting in late May through mid-September, usually two years after transplanting the crowns. Look for spears that are 6-8 inches tall with tight, closed tips. These are the most tender and flavorful.

To harvest, snap the spears off at ground level. Avoid cutting them, as this can damage the crown. Continue harvesting spears as they emerge, but stop when the spears become thin, about the width of a pencil. This indicates the plant needs to rebuild its energy reserves.

As the first frost approaches in early September, stop harvesting and allow all remaining spears to fern out. This will help the plant store energy for the following spring, ensuring a healthy and productive harvest next year.

Here are some common problems you might encounter with asparagus in the Mountain West:

Asparagus Beetle

• What it looks like: Small, elongated beetles (often orange or black) and their larvae feeding on spears and ferns. You might also see small, dark eggs attached to the spears.
• What causes it: These beetles are attracted to asparagus plants. Our intense sun can stress the plants, making them more vulnerable.
• How to fix/prevent it: Handpick beetles and larvae. Encourage beneficial insects like ladybugs. Use insecticidal soap as a last resort. Row covers can also help protect young plants.

Crown Rot from Poor Drainage

• What it looks like: Yellowing ferns, stunted growth, and mushy, rotting crowns.
• What causes it: Soggy soil, often due to poor drainage. Our alkaline soil can sometimes compact, exacerbating drainage issues.
• How to fix/prevent it: Ensure good drainage by planting in raised beds or amending the soil with organic matter. Avoid overwatering.

Thin Spears from Over-Harvesting

• What it looks like: Spears that are thin and weak, even after the initial harvest.
• What causes it: Harvesting too many spears for too long, depleting the plant's energy reserves.
• How to fix/prevent it: Limit your harvest to 8 weeks per season. Let plenty of spears fern out to replenish the plant's energy.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall usually mean fewer fungal diseases compared to more humid regions. However, the intense sun can stress plants, making them more susceptible to pests. Consistent watering and good soil preparation are crucial for success.

Companion planting can really help your asparagus thrive. Tomatoes, parsley, and basil are all good companions. Tomatoes deter asparagus beetles, while parsley attracts beneficial insects. Basil can help improve asparagus flavor and growth.

Avoid planting asparagus near onions or garlic. These plants can inhibit asparagus growth, possibly due to allelopathic compounds they release into the soil. Good companions can give you an edge in our short, intense growing season.