Chrysanthemum in Zone 7A — Midwest

Chrysanthemums add late-season color to our Midwest gardens when many other flowers are fading. Their cheerful blooms brighten up the landscape and make beautiful cut flower arrangements for your home. Plus, there's something immensely satisfying about extending the growing season with hardy plants.

The Midwest weather can be unpredictable, with our variable springs and occasional summer heat spells. But don't let that deter you! With a little planning and attention to timing, you can successfully grow chrysanthemums and enjoy their vibrant blooms throughout our 193-day growing season.

Starting chrysanthemums from seed indoors isn't the most common approach around here, but it's definitely doable if you want to get a head start or have a particular variety in mind. Start your seeds indoors in early to late February, about eight weeks before you plan to transplant them outside.

Use seed trays with a good seed-starting mix, and make sure they have adequate warmth and light. I like to bottom water my seed trays to encourage strong root growth and prevent damping off. Keep in mind that our springs in the Midwest can be moderate-to-late, so be prepared to protect your seedlings if we get a late frost.

Transplanting chrysanthemums outdoors is best done in early April through early May, after the danger of hard frost has passed. Before planting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the temperature and sunlight.

When transplanting, space your chrysanthemums about 12-18 inches apart. Keep an eye on the weather forecast, as we can sometimes get unexpected cold snaps in early spring. It's often easier to buy potted mums in the fall or starts in the spring from a local garden center.

Chrysanthemums need moderate watering, but it's important to get it right, especially with our Midwest humidity. Aim for consistent moisture, particularly when the plants are forming buds. I usually check the soil moisture with the finger test – stick your finger about two inches deep into the soil; if it feels dry, it's time to water.

During the summer heat spells, your chrysanthemums might need about an inch of water per week, either from rainfall or supplemental watering. Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid climate. Yellowing leaves can indicate overwatering, while wilting leaves signal underwatering. A layer of mulch around the base can help retain moisture and regulate soil temperature.

Pruning chrysanthemums is key to getting those full, bushy plants loaded with flowers. Pinch the growing tips of your chrysanthemums every 2-3 weeks until around July 4th. This encourages the plant to branch out and produce more flowering stems.

Make sure you're only pinching off the very tips of the stems, leaving the rest of the plant intact. After July 4th, stop pinching so the plants can set their flower buds for fall blooming. As the first frost approaches in mid- October, you can cut back the foliage to tidy up the garden.

Chrysanthemums bloom in the fall, so you can expect your first harvest of flowers from mid June through early August, about 70 days after transplanting. The flowers last for weeks in the garden, providing a beautiful display of color. Cut the flowers for bouquets when they are fully open.

When harvesting, use sharp scissors or pruners to cut the stems at an angle. This helps the plant heal quickly and encourages continued production. Deadhead spent flowers regularly to keep the plant looking tidy and promote more blooms. As the first frost approaches in mid- October, you can cut the remaining flowers to enjoy indoors before the cold weather sets in.

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 winding trails or blotches inside the leaves.
• What causes it: Larvae of small flies that burrow between the leaf surfaces.
• How to fix/prevent it: Remove and destroy infested leaves. Cover plants with row covers to prevent 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.

Midwest Specific Challenges: Our moderate-to-hot summers and moderate-to-humid conditions can create the perfect environment for fungal diseases like rust. Regularly monitor your plants and take preventative measures to ensure healthy growth.

Chrysanthemums make great companions for several plants in your Midwest garden. They can be planted near tomatoes and peppers, as the scent of chrysanthemums can help deter some common pests that affect these crops. Additionally, they work well alongside lettuce, providing some shade during the hotter parts of the day and helping to keep the soil cool.

Avoid planting chrysanthemums near plants that are heavy feeders, as they can compete for nutrients in our fertile soil. Also, keep them away from plants that are susceptible to the same diseases, to prevent the spread of any potential problems.