Chrysanthemum in Zone 6B — Mid-Atlantic

Chrysanthemums bring a burst of color to your garden just as other blooms are fading, extending the beauty of our four seasons. They're perfect for cut flower arrangements, adding a touch of late-season cheer to your home. Growing your own mums is incredibly rewarding, and they thrive in our Mid-Atlantic climate with a little attention.

We certainly have our gardening challenges here, from humid summers to deer pressure, but chrysanthemums are well-suited to our 198-day growing season if you plan accordingly. With proper timing and care, you can enjoy a stunning display of fall color.

Starting chrysanthemum seeds indoors isn't essential, as you can easily purchase established plants. However, if you're after a specific variety or want to get a head start, it's certainly doable. Begin in early to late February, about eight weeks before you plan to transplant outdoors.

Use seed trays with a good seed-starting mix, and keep them consistently moist. Bottom watering is ideal to prevent damping-off. Place the trays under grow lights or in a very sunny window. Given our moderate spring, having that extra light will really help those seedlings along.

Transplant your chrysanthemum seedlings outdoors from early April through early May. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the temperature and sunlight.

Space the plants 12-18 inches apart in a sunny spot with well-draining soil. Keep an eye on the weather forecast; we sometimes get unexpected late frosts in early April, so be ready to cover your young plants if needed. Many folks around here just buy starts in spring or potted mums in fall.

Chrysanthemums need consistent moisture, but they don't like to be waterlogged, especially with our humid summers. Aim to water them regularly at the base of the plant, avoiding overhead watering to prevent fungal diseases. Throughout the summer, that's especially important.

Check the soil moisture by sticking your finger about two inches deep. If it feels dry, it's time to water. Usually, about an inch of water per week is sufficient, but you might need to water more frequently during periods of intense heat and humidity. In the Mid-Atlantic, our even rainfall usually helps, but don't rely on it entirely.

Signs of underwatering include wilting leaves and dry soil. Overwatering can lead to yellowing leaves and root rot. A good layer of mulch around the base of the plants will help retain moisture and suppress weeds, which is helpful with our clay soil.

Pruning chrysanthemums is key to getting those beautiful, bushy plants loaded with flowers. Start pinching off the growing tips every two to three weeks from when the plants are young until around July 4th. This encourages the plant to branch out and produce more flower buds.

When you pinch, remove just the top set of leaves. After July 4th, stop pinching to allow the flower buds to develop fully. At the end of the season, after the first frost in late October, you can cut the plants back to a few inches above the ground.

You can expect your first chrysanthemum blooms from mid June through early August, depending on the variety and when you transplanted. Chrysanthemums are fall-blooming, so that's when you'll really see them shine. The flowers last for weeks in the garden, providing a long-lasting display.

Cut the flowers for bouquets when they are fully open and the petals are firm. Use clean, sharp scissors or pruners to avoid damaging the plant. Cutting the flowers encourages the plant to produce more blooms, so keep harvesting throughout the season.

As the first frost approaches in late October, you can cut any remaining flowers to enjoy indoors. While chrysanthemums are hardy, the blooms themselves won't survive a hard frost.

Here are some common problems you might encounter with chrysanthemums in the Mid-Atlantic:

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).

Spider Mites *What it looks like:* Fine stippling on leaves (tiny white dots). Fine webbing on leaf undersides and between stems. Leaves turn bronze or yellow. *What causes it:* Tiny arachnids that thrive in hot, dry conditions. Populations explode in drought stress. *How to fix/prevent it:* Strong water spray (daily for a week) is the best treatment. Increase humidity around plants. Neem oil or insecticidal soap. Release predatory mites (Phytoseiulus persimilis). Avoid broad-spectrum pesticides that kill predators.

Leaf Miners *What it looks like:* White or yellow winding trails on leaves. Blistered or distorted foliage. *What causes it:* Larvae of small flies that tunnel between leaf surfaces to feed. *How to fix/prevent it:* Remove and destroy infested leaves. Cover plants with floating row covers to prevent adult flies from laying eggs. Neem oil can deter egg-laying.

Rust *What it looks like:* Rusty orange, yellow, or brown pustules on leaves and stems, mostly on undersides. Leaves yellow and drop prematurely. *What causes it:* Various rust fungi that spread via wind-borne spores. Favored by warm, humid conditions with moisture on leaves. *How to fix/prevent it:* Remove affected leaves. Avoid overhead watering. Improve air circulation. Apply sulfur or copper fungicide. Don't work among wet plants. Rotate crops.

Mid-Atlantic Specific Challenges: Our moderate-to-hot heat and humid summers create ideal conditions for fungal diseases like rust and pest infestations like aphids and spider mites on chrysanthemums. Be vigilant about monitoring your plants and take action early to prevent problems from getting out of control.

Chrysanthemums benefit from companion planting. Tomatoes and peppers make good companions because they deter some pests that might bother your mums. Lettuce also works well, as it provides ground cover that helps retain moisture in our sometimes dry spells.

Avoid planting chrysanthemums near anything that attracts aphids, as this can increase the risk of infestation.