Black-Eyed Susan in Zone 5B — Mountain West

Black-Eyed Susans are a burst of sunshine in our Mountain West gardens. Their vibrant yellow petals bring cheer to our short growing season, and they're surprisingly low-maintenance once established. Plus, they make fantastic cut flowers to brighten up your home, offering a taste of summer even as the cool nights start creeping in.

Our high altitude and intense sun can be tough on plants, and our short growing season requires careful planning. But Black-Eyed Susans, with their 75-day maturity, fit nicely into our 149-day season. With a little attention to timing, you'll enjoy a profusion of blooms from midsummer through fall.

Starting Black-Eyed Susans indoors in our climate is definitely an option, especially if you're eager for earlier blooms. You'll want to start your seeds indoors from late February through mid March, roughly 8 weeks before you plan to transplant them outside.

Use seed trays with a good seed-starting mix. Keep them consistently moist (bottom watering is great for this) and provide warmth and plenty of light – a grow light is ideal. Remember that spring can be slow to arrive here, so starting early gives your plants a head start before our last frost.

Transplant your Black-Eyed Susans outdoors from late April through late May, after the danger of hard frost has passed. Remember to harden them off for about a week before planting by gradually exposing them to outdoor conditions.

Space them 12-18 inches apart to allow for good air circulation. Keep an eye on the weather forecast; even in late spring, we can get a surprise hailstorm or a late freeze that could damage tender transplants. Black-Eyed Susans are perennials, so buying starts allows you to enjoy flowers the first year.

Direct sowing Black-Eyed Susan is a straightforward way to get these beauties growing. Sow seeds directly into the garden from early May through early July, once the soil has warmed up a bit.

Prepare the soil by loosening it and removing any weeds. Sow seeds about 1/4 inch deep and keep the soil consistently moist until germination. Thin seedlings to 12-18 inches apart. Direct sowing is less work upfront, but you'll have to wait longer for blooms compared to starting indoors or transplanting starts.

Black-Eyed Susans are quite drought-tolerant, which is a huge plus in our dry Mountain West climate. However, they do need consistent watering while getting established.

During their first season, water deeply about once a week, providing about an inch of water. Use the "finger test" – if the top two inches of soil feel dry, it's time to water. After they're established, you'll only need to water during extended dry spells. In our climate, that usually means a deep watering every two to three weeks during the hottest part of the summer.

Water at the base of the plants to avoid wetting the foliage, which can help prevent fungal diseases in our low-humidity environment. Signs of underwatering include wilting leaves; overwatering can lead to yellowing leaves and potentially root rot. A layer of mulch around the base of the plants will help retain moisture and suppress weeds.

Deadheading Black-Eyed Susans will encourage them to produce more flowers throughout the growing season. Simply snip off the spent blooms just below the flower head.

If you want to leave some seed heads for the birds or allow the plants to self-seed, you can skip deadheading some of the later blooms. In late winter or early spring, before new growth begins, cut back the entire plant to a few inches above the ground to promote vigorous growth.

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

Cut the stems at an angle, leaving several inches of stem on the plant. Removing spent blooms encourages the plant to produce more flowers, extending the blooming season. As the first frost approaches in early October, you can harvest any remaining blooms to enjoy indoors. The seed heads can be left on the plants to provide food for birds during the winter.

Here are a few common problems you might encounter with Black-Eyed Susans in our region:

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves curl, yellow, and die.
• What causes it: Fungi 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: Small, circular spots on leaves that start yellow and turn brown or black. Spots may have a light center. Severe infections cause leaves to drop.
• What causes it: A fungal disease that spreads through splashing water and infected plant debris. Our cool nights and occasional summer rains can create favorable conditions.
• How to fix/prevent it: Remove and destroy infected leaves. Improve air circulation. Water at the base of the plants to avoid wetting foliage. Apply a copper-based fungicide if necessary.

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 generally help reduce the severity of fungal diseases compared to more humid climates. However, our intense UV radiation can stress plants, making them more susceptible to pests. Consistent watering and well-draining soil are key to keeping your Black-Eyed Susans healthy and resilient.

Black-Eyed Susans are great companions for several plants in our Mountain gardens. Planting them near tomatoes and squash can help attract pollinators, increasing fruit production. Herbs like rosemary and thyme can also be beneficial, as they deter some pests. Avoid planting Black-Eyed Susans near plants that are susceptible to powdery mildew, as this can increase the risk of spreading the disease.