Strawberry in Zone 6A — Mountain West

There's nothing quite like the taste of a sun-ripened strawberry, and even with our cool nights at altitude, you can absolutely grow them here in the Mountain West. The bright, intense sunlight concentrates the sugars, and that fresh-picked flavor is unmatched. Plus, strawberries are so versatile: jams, desserts, or just eaten straight from the plant – the possibilities are endless.

Our short growing season and alkaline soil present some challenges, but with careful planning, you can enjoy a bountiful strawberry harvest. The 153-day growing season means starting with transplants is the way to go. The timing, mid-April through early May, works well to get them established before the summer heat hits.

Transplant your strawberry starts outdoors from mid-April through early May. You'll find bare-root plants or potted starts at local nurseries this time of year. Growing from seed is just too slow for our short season.

Before planting, harden off your transplants by gradually exposing them to the outdoors for about a week. This helps them adjust to the intense sun and cooler temperatures of our Mountain climate. Space the plants 12-18 inches apart in well-draining soil.

Keep an eye on the weather forecast. Unexpected late frosts are always a possibility in the Mountains, even in late spring. Be prepared to cover your new transplants if temperatures dip near freezing.

Strawberries need consistent moisture, especially when they're fruiting. Because of our dry climate, aim for about 1 inch of water per week, more if the weather is particularly hot and dry. The finger test is a good way to check: stick your finger about 2 inches into the soil. If it feels dry, it's time to water.

Water at the base of the plants rather than overhead. Our low humidity minimizes the risk, but wet foliage can still lead to fungal problems. Drip irrigation is ideal for delivering water directly to the roots.

Signs of underwatering include wilting leaves and dry, crumbly soil. Overwatering can cause root rot, indicated by yellowing leaves and a soggy soil. Mulch heavily around your strawberry plants. This helps retain moisture in our dry air, suppress weeds, and keep the berries clean. Use straw, wood chips, or pine needles, all readily available in the Mountain West.

Strawberry pruning is pretty simple. The main thing is to manage the runners. These are the little stems that pop out.

Throughout the growing season, remove the runners to encourage the plants to put their energy into fruit production. If you want more strawberry plants, you can let a few runners root in the soil to create new plants. After you've harvested all the berries from June-bearing varieties, you can renovate the bed by mowing off the foliage close to the ground. This encourages new growth for the following year. As the first frost approaches in early October, remove any dead or diseased leaves to prevent overwintering pests and diseases.

You can expect your first strawberry harvest from mid-July through late August, depending on the variety and the weather. Strawberries are ready to pick when they are fully red, plump, and fragrant, with no white or green shoulders. The flavor won't improve after picking, so make sure they're ripe before you harvest.

Gently pluck the berries from the plant, leaving the green cap attached. Picking in the morning, after the dew has dried, often results in the best flavor. Keep harvesting regularly to encourage continued production.

As the first frost approaches in early October, harvest any remaining ripe or nearly ripe berries. You can use these in jams or smoothies. Remove any remaining foliage to prepare the plants for winter dormancy.

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

Gray Mold

• What it looks like: Fuzzy gray mold on the berries, especially during wet periods.
• What causes it: A fungal disease that thrives in humid conditions. While our humidity is low, spring and early summer can have periods of moisture.
• How to fix/prevent it: Improve air circulation by spacing plants properly. Remove infected berries promptly. Apply a fungicide if the problem is severe.

Slugs

• What it looks like: Irregular holes in leaves, especially low-growing plants. Silvery slime trails on leaves and soil. Damage worse at night and in wet weather.
• What causes it: Gastropods that feed at night in moist conditions. Hide under mulch, boards, and debris during the day.
• How to fix/prevent it: Beer traps (shallow dish of beer sunk into soil). Iron phosphate bait (pet-safe). Remove hiding spots. Water in morning so soil surface dries by evening. Copper tape around beds. Diatomaceous earth around plants.

Birds

• What it looks like: Missing berries or berries with peck marks.
• What causes it: Birds love strawberries!
• How to fix/prevent it: Cover your strawberry plants with netting to protect the berries.

Strawberry Crown Borer

• What it looks like: Wilting plants, stunted growth, and small holes in the crown of the plant.
• What causes it: A beetle larva that bores into the crown of the plant, weakening or killing it.
• How to fix/prevent it: Remove and destroy infested plants. Rotate crops. Apply beneficial nematodes to the soil.

Verticillium Wilt

• What it looks like: Lower leaves yellow, wilt, and die, progressing upward. One side of plant may be affected first. Brown streaks in stem cross-section.
• What causes it: Soil-borne fungus that persists for years. Cooler soil temperatures favor it (unlike fusarium). Wide host range.
• How to fix/prevent it: No cure — remove infected plants. Rotate with non-susceptible crops (corn, grains). Solarize soil. Plant resistant varieties (look for 'V' on labels).

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity generally reduce disease pressure on strawberries. However, the intense UV light can sometimes scorch the berries, so providing some afternoon shade during the hottest part of the summer can be helpful. And even though our rainfall is dry, spring hail can damage plants and berries.

Companion planting can be beneficial for strawberries. Lettuce and spinach make good companions because they provide ground cover, helping to retain moisture and suppress weeds. Onion and garlic are also good choices, as their strong scent deters pests. Thyme, planted nearby, attracts beneficial insects that prey on strawberry pests. Borage is another excellent companion, attracting pollinators and deterring pests with its scent.

Avoid planting strawberries near broccoli, cauliflower, pepper, and tomato. These plants compete for nutrients and can attract pests and diseases that also affect strawberries. The alkaline soil can cause nutrient deficiencies in these plants, further stressing them and making them less productive.