Chrysanthemum in Zone 6B — Southeast

Chrysanthemums bring a burst of color to the garden when many other flowers are fading, which is a welcome sight after our long, hot summers. Their versatility as cut flowers also makes them a favorite. Plus, there’s a real sense of accomplishment in coaxing these beauties to thrive in our Southeast gardens.

We definitely have our share of gardening challenges here – humidity, fungal diseases, and those ever-present Japanese beetles. But with the right timing and a few smart strategies, you can absolutely grow gorgeous chrysanthemums during our 208-day growing season.

Starting chrysanthemums indoors isn't always necessary, especially since you can find healthy starts at local nurseries in the spring. But if you're after a specific variety or just enjoy starting from seed, it's certainly doable. Start your seeds indoors from early to late February, about 8 weeks before you plan to transplant.

Use seed trays with a good seed-starting mix and provide warmth and light – a sunny windowsill or grow lights work well. Bottom watering is a great way to keep the soil consistently moist without overwatering or encouraging fungal issues. Given our moderate spring weather in the Southeast, you'll want to keep a close eye on soil moisture.

Once the danger of frost has passed, usually from early April through early May, it's time to transplant your chrysanthemum seedlings outdoors. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sunlight, wind, and temperature fluctuations.

Plant them 12-18 inches apart in a sunny spot with well-draining soil. Keep an eye on the weather forecast around transplant time – those late-season cold snaps can still happen. You can also buy established mums in the fall for an instant burst of color, or purchase starts in the spring from local nurseries.

Watering is key for healthy chrysanthemums, especially in our hot, humid Southeast climate. While they need consistent moisture, they definitely don't like sitting in soggy soil, which can lead to root rot. A good rule of thumb is to water deeply when the top 2 inches of soil feel dry to the touch – the "finger test".

During the hotter months, you'll likely need to water a couple of times a week, providing about an inch of water each time, either from rainfall or irrigation. In the spring and fall, you can usually scale back to once a week, unless we're experiencing a dry spell. Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid climate.

Watch for signs of underwatering, like wilting leaves, or overwatering, like yellowing leaves and mushy stems. A layer of mulch around your plants helps retain moisture and suppress weeds, but keep it away from the stems to prevent rot.

Pruning chrysanthemums is essential for encouraging a bushy growth habit and abundant blooms. The main technique is pinching – simply remove the growing tips of the stems every 2-3 weeks from spring until around July 4th. This encourages the plant to branch out and produce more flowering stems.

After July 4th, stop pinching to allow the flower buds to develop. As the season winds down and we approach our first frost around late October, you can cut back the plants to a few inches above the ground after they've finished blooming. This helps them conserve energy for the winter.

You can expect your first chrysanthemum blooms from mid-June through early August, depending on the variety and when you transplanted. Chrysanthemum flowers last for weeks in the garden, providing a long-lasting display of color. To harvest them for bouquets, cut the stems when the flowers are fully open and the petals are firm.

Cut the stems at an angle, just above a leaf node, to encourage new growth. Regular harvesting encourages continued production throughout the season. As the first frost approaches in late October, harvest any remaining blooms before they get damaged.

Here are some common problems to watch out for with chrysanthemums in the Southeast:

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides, often with sticky honeydew. You might also notice curled or distorted new growth.
• What causes it: These sap-sucking insects reproduce rapidly, especially in warm weather. Ants often protect them for their honeydew.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage natural predators like ladybugs. For heavy infestations, use insecticidal soap or neem oil. Avoid over-fertilizing with nitrogen.

Spider Mites

• What it looks like: Fine stippling on leaves (tiny white dots), fine webbing on leaf undersides, and leaves turning bronze or yellow.
• What causes it: These tiny arachnids thrive in hot, dry conditions. Drought stress makes plants more susceptible.
• How to fix/prevent it: A strong spray of water, daily for a week, is often enough. Increase humidity around the plants. Neem oil or insecticidal soap can also help.

Leaf Miners

• What it looks like: Tan or white squiggly lines or blotches on leaves.
• What causes it: The larvae of certain flies or moths tunnel between the upper and lower leaf surfaces, feeding on the leaf tissue.
• How to fix/prevent it: Remove and destroy affected leaves. For severe infestations, apply neem oil. Prevent leafminers by covering your plants with row covers early in the season.

Rust

• What it looks like: Rusty orange, yellow, or brown pustules on leaves and stems, mostly on undersides. Leaves may yellow and drop prematurely.
• What causes it: Various rust fungi spread via wind-borne spores, favored by warm, humid conditions and 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.

Southeast Specific Challenges: Our hot, humid summers create the perfect environment for fungal diseases like rust, so good air circulation and avoiding overhead watering are crucial. Japanese beetles can also be a nuisance, so consider using traps or hand-picking them off plants. Deer are always a concern, so fencing or deer-resistant sprays are helpful.

Chrysanthemums make good companions for several vegetables in the Southeast garden. Planting them near tomatoes and peppers can help repel some pests, as chrysanthemums contain pyrethrum, a natural insecticide. They also do well planted near lettuce, providing some shade during the hottest part of the day and helping to keep the soil cool.

Avoid planting them near fennel, as fennel can inhibit the growth of many plants, including chrysanthemums.