Blackberry in Zone 6B — Mountain West

Blackberries are a rewarding addition to any Mountain West garden. Their intense flavor, perfect for jams, pies, or just eating fresh, is even better thanks to our cool nights. Plus, growing your own means you get to enjoy sun-ripened berries picked at their peak, something you just can't replicate with store-bought fruit.

Our high altitude, intense sun, and short growing season present unique challenges, but blackberries are surprisingly adaptable. By understanding the timing and needs of these plants, you can enjoy a bountiful harvest within our 163-day growing season.

Transplant your blackberry plants outdoors from late April through late May, after the last expected frost. Be sure to harden off your bare-root canes or potted plants for about a week before transplanting. Gradually expose them to the outdoor elements so they don't get shocked by our intense UV and temperature swings.

Space your plants 3-5 feet apart to allow for good air circulation and plenty of room to spread. Remember we can get late-season snow or hail, so consider temporary row covers if a late cold snap is forecast.

Blackberries need consistent moisture, especially while they're fruiting, but they don't like soggy roots. Aim for moderate watering, keeping in mind our dry Mountain West climate. Once established, blackberries are more drought-tolerant than raspberries, but that doesn't mean you can neglect them.

During the heat of summer, check the soil moisture using the "finger test." Stick your finger about 2 inches deep into the soil near the base of the plant. If it feels dry, it's time to water. Usually, an inch of water per week is sufficient, but you might need to increase that during especially hot or windy periods. Water deeply at the base of the plant, avoiding overhead watering, which can encourage fungal diseases in our cool evenings.

If the leaves are wilting or turning yellow, you might be underwatering. If the leaves are yellowing and the plant seems stunted, you might be overwatering. A good layer of mulch, like wood chips or straw, will help retain moisture and suppress weeds.

Blackberries are vining plants that need a strong support system to thrive. A trellis is the best option, providing the necessary structure for the canes to climb and spread. Install the trellis before you plant your blackberries to avoid disturbing the roots later.

A simple two-wire trellis works well. Run wires horizontally at about 3 and 5 feet above the ground, securing them to sturdy posts. As the canes grow, train them along the wires, tying them loosely with twine or plant tape. Thornless varieties are much easier to manage on a trellis, making pruning and harvesting less painful.

Blackberries require minimal pruning but it's essential for maintaining productivity and plant health. After harvest, remove the spent floricanes (the canes that produced fruit) at ground level. These canes won't produce again, and removing them improves air circulation.

In late spring or early summer, tip-prune the new primocanes (the current year's growth) at about 4-5 feet tall. This encourages branching, which leads to more fruit the following year. As the first frost approaches in early October, cut back any excessively long canes to prevent winter damage.

Your first blackberry harvest should arrive sometime between late June and mid-August, depending on the variety and the weather. The berries are ready to pick when they are fully black, not dark red, and pull off the stem easily without squeezing. A dull surface, rather than a shiny one, is also a good indicator of ripeness.

Pick berries every few days as they ripen to encourage continued production. Gently grasp the ripe berries and pull them away from the plant, being careful not to damage the canes. As the first frost approaches in early October, harvest any remaining ripe or nearly ripe berries.

Blackberries, like any plant, can be susceptible to certain problems. Here are a few common issues you might encounter in the Mountain West:

• Spotted Wing Drosophila
• What it looks like: Tiny, soft-bodied flies that lay eggs in ripening fruit, causing soft spots and rot.
• What causes it: These flies thrive in humid conditions, but can still be a problem in our region, especially after rain.
• How to fix/prevent it: Monitor traps, prune for air circulation, and consider netting to exclude the flies. Remove and destroy any infested fruit.
• Cane Blight
• What it looks like: Dark, sunken lesions on the canes, often near pruning cuts.
• What causes it: A fungal disease that enters through wounds in the canes.
• How to fix/prevent it: Prune carefully, avoid wounding the canes, and disinfect pruning tools. Remove and destroy any infected canes.
• Orange Rust
• What it looks like: Bright orange pustules on the undersides of the leaves.
• What causes it: A systemic fungal disease that infects the entire plant.
• How to fix/prevent it: Remove and destroy any infected plants. There is no cure for orange rust.
• Japanese Beetles
• What it looks like: Metallic green beetles that skeletonize the leaves.
• What causes it: These beetles are attracted to stressed plants.
• How to fix/prevent it: Handpick beetles, use insecticidal soap, or apply neem oil.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity generally reduce disease pressure on blackberries. However, the intense sun can scorch the leaves if the plants are not properly watered. Hail can also damage the canes and fruit, so consider using netting or row covers during hail-prone periods.

Companion planting can help your blackberries thrive.

• Good companions: Tansy repels Japanese beetles, garlic deters pests, green beans fix nitrogen in the soil, and mint attracts beneficial insects.
• Bad companions: Avoid planting tomatoes, peppers, and potatoes near blackberries, as they can attract similar pests and diseases. These nightshades compete for nutrients and can harbor blight.