Black-Eyed Susan in Zone 3A — Mountain West

Black-Eyed Susans bring a burst of sunny color to our short Mountain growing season. Their cheerful blooms attract pollinators and add a wildflower charm to any garden. Plus, they're incredibly low-maintenance once established, perfect for our busy summers when we'd rather be hiking than constantly watering.

High altitude gardening in the Mountain West definitely comes with its challenges. Intense UV, alkaline soil, and a short 96-day growing season mean we have to be smart about timing. But with a little planning, you can enjoy these hardy perennials year after year.

Starting Black-Eyed Susans indoors gives you a jump start on our short season, but it's not always necessary. If you're aiming for blooms in the first year, or if you want to get a head start, indoor sowing is a good option. Start seeds indoors late March through mid April, about 8 weeks before you plan to transplant.

Use seed trays with a good seed-starting mix. Keep them warm (around 70°F) and provide plenty of light. Bottom watering will help prevent damping off, which can be a problem in our cool spring conditions. Remember, our springs can be slow to warm up, so be patient!

Transplant your Black-Eyed Susan seedlings outdoors late May through early June, after the risk of frost has passed. Before planting, harden them off for about a week by gradually exposing them to outdoor conditions. This helps them adjust to our intense sun and fluctuating temperatures.

Space your plants 12-18 inches apart in a sunny location. Our late frosts are always a concern, so keep an eye on the forecast. If a cold snap is predicted, cover your transplants with row covers or blankets. Black-Eyed Susans are perennial, so if you buy starts, you'll likely see flowers in the first year.

Direct sowing Black-Eyed Susan is a simple method, especially if you're not in a rush for first-year blooms. Wait until early June, when the soil has warmed up. Prepare the soil by loosening it and removing any weeds.

Sow seeds about ¼ inch deep and keep the soil consistently moist until they germinate. Thin seedlings to 12-18 inches apart once they have a few sets of true leaves. Direct sowing is easy, but keep in mind that seedlings might take longer to establish compared to transplants.

Black-Eyed Susans are known for their drought tolerance, a definite plus in our dry Mountain climate. Once established, they need very little supplemental watering. However, getting them established requires some attention.

During the first few weeks after transplanting or germination, water regularly to help them develop strong roots. After that, water only when the top 2 inches of soil feel dry to the touch – the "finger test." In our dry climate, this might mean watering once a week, or even less frequently during cooler periods. Aim for about 1 inch of water per week when you do water.

Water at the base of the plants to avoid wetting the foliage. Overhead watering in our low-humidity environment isn't as risky as in more humid climates, but watering at the base still minimizes the risk of fungal diseases. Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, so be sure the soil is well-draining. A layer of mulch around the base of the plants will help retain moisture and suppress weeds.

Deadheading Black-Eyed Susans is key to encouraging a longer bloom period. Simply snip off the spent flowers just below the flower head. This prevents the plant from putting energy into seed production and encourages it to produce more blooms.

You can deadhead throughout the growing season, from midsummer until the first frost. Alternatively, leave some seed heads in the fall to provide food for birds and to allow the plants to self-seed. In late winter or early spring, cut back the entire plant to a few inches above the ground to encourage new growth.

You can expect your first Black-Eyed Susan blooms mid August through mid September, about 75 days after sowing. The flowers are ready to harvest when they are fully open and the petals are vibrant.

To harvest, cut the stems at an angle, leaving a few inches of stem on the plant. This encourages the plant to produce more blooms. Black-Eyed Susans make excellent cut flowers and will last for several days in a vase.

Continue harvesting throughout the blooming season to encourage continuous production. As the first frost approaches around early September, you can either cut back the plants or leave the seed heads for the birds.

Even though Black-Eyed Susans are fairly easy to grow, here are a few problems you might encounter in our Mountain climate:

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves curl, yellow, and die.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is surprisingly effective. Plant resistant varieties.

Septoria Leaf Spot

• What it looks like: Dark brown or black spots on leaves, often with a yellow halo. Spots can merge, causing leaves to yellow and drop.
• What causes it: A fungal disease that spreads through splashing water. Our intense sun can stress plants, making them more susceptible.
• How to fix/prevent it: Remove and destroy infected leaves. Water at the base of the plant to avoid wetting the foliage. Improve air circulation. Copper fungicide can help prevent spread.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer (it attracts them).

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity can actually be beneficial for Black-Eyed Susans, reducing the risk of many fungal diseases. However, the intense UV can stress the plants, making them more susceptible to pests. Make sure to provide adequate water and consider using shade cloth during the hottest part of the day.

Black-Eyed Susans make great companions for many garden plants. They attract pollinators, which can benefit fruiting vegetables like tomatoes and squash. Plus, their bright colors add visual appeal to the garden.

Good companions include:

• Tomatoes: The pollinators attracted by Black-Eyed Susans will also pollinate your tomatoes, leading to a better harvest.
• Squash: Similar to tomatoes, squash benefits from increased pollination.
• Herbs: Many herbs, such as rosemary and thyme, have strong scents that can help deter pests from Black-Eyed Susans.

Avoid planting Black-Eyed Susans near plants that require very rich soil or frequent watering, as they prefer drier conditions.