Chrysanthemum in Zone 5A — Midwest

Chrysanthemums bring a burst of color to the garden just as other flowers are fading, making them a welcome sight in the Midwest. Their blooms last for weeks, and they make great cut flowers to brighten up your home. Plus, they're relatively easy to grow, adding a touch of beauty to your late summer and fall garden.

The Midwest weather can be a bit unpredictable, with occasional summer heat spells and the chance of early frosts. However, with a bit of planning and the right timing, you can absolutely enjoy beautiful Chrysanthemums in our 157-day growing season.

Starting Chrysanthemums indoors is possible, but honestly, it's more common to buy established plants. If you're set on starting from seed, aim for late February through mid March, about eight weeks before you plan to transplant.

Use seed trays with a good seed-starting mix, and keep them in a warm spot, ideally with a heat mat. Bottom watering is great for seedlings; just set the tray in a shallow dish of water and let the soil soak it up. Since our springs can be moderate-to-late here in the Midwest, starting indoors gives you a head start.

Transplanting Chrysanthemums outdoors is best done in early to late May, after the risk of frost has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Space them 12-18 inches apart in a sunny spot with fertile soil. Keep an eye on the weather forecast; even in May, we can still get a late frost, so be prepared to cover your young plants if needed. Alternatively, you can purchase potted mums in the fall or starts in the spring from local nurseries.

Chrysanthemums need consistent moisture, but they don't like to be soggy. In the Midwest, with our moderate-to-humid summers and typical highs around 86°F, watering needs to be balanced.

During the hotter parts of the summer, check the soil moisture every few days using the "finger test"—stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or supplemental watering. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid climate.

Signs of underwatering include wilting leaves and dry, brittle stems. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your plants helps retain moisture and regulate soil temperature, which is especially helpful during our summer heat spells.

Pruning Chrysanthemums is simple and helps create bushier plants with more flowers. The key is to "pinch" the growing tips every 2-3 weeks, starting when the plants are about 6 inches tall and continuing through July 4th.

Pinch off the top set of leaves on each stem, leaving the rest of the plant intact. This encourages side shoots to develop, resulting in more blooms. After July 4th, stop pinching to allow flower buds to form. As the first frost approaches in early October, you can cut back the plants to a few inches above the ground.

You can expect your first Chrysanthemum blooms in early July through late August, about 70 days after transplanting. Chrysanthemums are fall-blooming, so get ready for a colorful display!

The flowers last for weeks in the garden, and they're ready to cut for bouquets when they're fully open. To harvest, simply cut the stems at an angle, leaving several leaves on the plant to encourage continued production. As the first frost approaches in early October, cut any remaining blooms to enjoy indoors.

Here are some common problems you might encounter with Chrysanthemums in the Midwest:

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: Tan or white winding trails on leaves. Blotch-like mines within the leaf tissue.
• What causes it: Larvae of small flies that tunnel between leaf surfaces, feeding on the inner tissue.
• How to fix/prevent it: Remove and destroy affected leaves. Insecticidal soap or neem oil early in the infestation. Floating row covers can prevent adult flies from laying eggs on plants.

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.

Midwest Specific Challenges: The moderate-to-hot heat and moderate-to-humid humidity of the Midwest can create ideal conditions for fungal diseases like rust. Regular monitoring and good air circulation are key. Our wet summers can also exacerbate these problems, so be mindful of watering practices.

Chrysanthemums benefit from companion planting. Tomatoes and peppers make good companions because they deter some common pests that affect Chrysanthemums. Plus, they all enjoy similar growing conditions, like full sun and fertile soil. Lettuce can also be a good companion, as it provides ground cover that helps retain moisture and suppress weeds.

Avoid planting Chrysanthemums near plants that are prone to fungal diseases, as this can increase the risk of spreading those diseases to your Chrysanthemums, especially in our humid Midwest summers.