Raspberry in Zone 7A — Mountain West

Raspberries are a rewarding addition to any Mountain West garden. Their sweet, tangy flavor shines in jams, desserts, or simply eaten fresh off the cane. The satisfaction of harvesting your own berries, bursting with flavor intensified by our cool nights, is hard to beat.

Our high altitude, intense sun, and alkaline soil present unique challenges. But with careful timing, you can absolutely grow raspberries successfully here. Our 173-day growing season gives you a window to produce a satisfying crop.

Transplant your raspberry plants outdoors from mid-April through mid-May. This timing allows them to establish before the heat of summer sets in. Remember to harden off your bare-root canes or potted plants for about a week before transplanting. Gradually expose them to the sun and wind to prevent shock.

Space your raspberry plants 2-3 feet apart to allow for adequate air circulation. Keep an eye on the weather forecast; a late-season frost or hailstorm can damage young plants, so be prepared to cover them if necessary.

Raspberries need consistent moisture, but avoid waterlogged soil. Aim for about 1-2 inches of water per week, especially during fruit development. Drip irrigation is ideal because it delivers water directly to the roots, minimizing water loss from evaporation in our dry climate.

In the Mountain West, our watering schedule shifts with the seasons. Increase watering frequency as temperatures rise in late spring and summer, especially during those weeks when we get those moderate-at-altitude high temps. Use the "finger test" – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. In the fall, gradually reduce watering as the plants prepare for dormancy.

Water at the base of the plants rather than overhead to avoid fungal diseases, which are less common due to our low humidity but can still occur. Signs of underwatering include wilting leaves and dry, crumbly soil. Overwatering can lead to yellowing leaves and root rot. Mulching around the base of your raspberry plants with organic matter like wood chips or straw helps retain moisture and regulate soil temperature.

Raspberry canes benefit greatly from support. A simple two-wire trellis system works wonders. Install the trellis at planting time, setting posts at the ends of your row and running wires at about 2 and 4 feet above the ground.

As the canes grow, gently train them to the wires, tying them loosely with twine or plant tape. This prevents the canes from flopping over, which can make harvesting difficult and increase the risk of disease. Supporting your plants also maximizes sun exposure, leading to better fruit production.

Pruning is essential for maintaining healthy and productive raspberry plants. For summer-bearing varieties, remove the spent canes after you've harvested all the berries. Cut them all the way down to the ground. These canes won't produce fruit again.

For everbearing raspberries, you have a choice. You can cut all the canes down to the ground in late winter for one large fall crop. Or, you can selectively prune the tips of the canes after the first harvest to encourage a second, smaller crop. As the first frost approaches in early October, remove any remaining unripe fruit to encourage the plant to focus its energy on winter dormancy.

Expect your first raspberry harvest from mid-June through early August, depending on the variety and the weather. The berries are ready to pick when they are deeply colored and pull easily from the core. A ripe berry will release with just a gentle tug.

Pick your raspberries every 2-3 days during peak season to prevent them from becoming overripe and attracting pests. Handle the berries gently to avoid bruising them. To encourage continued production, keep the plants well-watered and fertilized. As the first frost approaches in early October, harvest any remaining ripe berries and consider covering the plants if a hard freeze is predicted to extend the harvest a little longer.

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

• Spotted Wing Drosophila
• What it looks like: Tiny flies lay eggs in ripening fruit, causing soft spots and rot. You might see small larvae inside the berries.
• What causes it: These pests thrive in humid conditions, though even our low humidity doesn't eliminate them entirely.
• How to fix/prevent it: Use traps to monitor and reduce populations. Netting can exclude the flies. Harvest frequently and remove overripe fruit.
• Cane Borer
• What it looks like: Wilting or dying canes with small holes in them. You may see swelling or galls on the canes.
• What causes it: Cane borers are beetles that lay eggs in the canes, and the larvae tunnel through the wood.
• How to fix/prevent it: Prune out and destroy infested canes below the point of damage. Keep the area around your plants free of weeds and debris.
• Gray Mold (Botrytis)
• What it looks like: Gray, fuzzy mold on the fruit and sometimes the canes. Berries become soft and mushy.
• What causes it: This fungal disease is favored by cool, wet conditions.
• How to fix/prevent it: Ensure good air circulation by spacing plants properly and pruning. Remove infected fruit and canes promptly. Avoid overhead watering.
• Raspberry Crown Borer
• What it looks like: Weakened plants with reduced growth and yield. You may find large, yellowish-white grubs in the crown and roots.
• What causes it: These pests bore into the crown of the plant, damaging the tissue and disrupting nutrient flow.
• How to fix/prevent it: Difficult to control once established. Remove and destroy infested plants. Consider using nematodes to control larvae in the soil.

Mountain West Specific Challenges: While our low humidity helps reduce fungal diseases, the intense sun can stress plants, making them more susceptible to pests. Our alkaline soil can also affect nutrient uptake, so amend your soil with compost and consider using fertilizers formulated for acidic-loving plants. Hail is a risk, so consider netting if you are in a high-risk area.

Good companions for raspberries include garlic, tansy, and marigolds. Garlic and tansy are believed to deter pests with their strong scents. Marigolds attract beneficial insects that prey on harmful pests.

Avoid planting raspberries near potatoes, tomatoes, peppers, and blackberries. Potatoes, tomatoes, and peppers can harbor diseases that can spread to raspberries. Blackberries compete for resources and can also spread diseases.