Chrysanthemum in Zone 3B — Midwest

Chrysanthemums bring a burst of vibrant color to your Midwest garden just as other flowers are fading. Their late-season blooms provide a welcome splash of beauty, and they're perfect for fall bouquets to brighten up your home as the days get shorter. Plus, they're relatively easy to grow and offer a long-lasting display of color.

Our Midwest weather can be unpredictable, with late frosts in spring and the occasional summer heat spell. However, with a little planning and attention to timing, you can absolutely enjoy a stunning display of chrysanthemums in your garden. Our 118-day growing season is plenty to get them going.

Starting chrysanthemums from seed indoors is possible, but most Midwest gardeners find it easier to purchase starts from a local nursery in the spring. If you're up for the challenge, starting seeds indoors from mid-March through early April gives them about eight weeks to get a head start before transplanting.

Use seed trays with a good seed-starting mix and keep them consistently moist, bottom watering works best. You'll need a warm location and a grow light to ensure strong, healthy seedlings. Keep in mind that our springs are moderate-to-late, so be patient and don't rush them outside too early.

Transplant your chrysanthemum seedlings outdoors from mid-May through mid-June, after the risk of 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 in fertile soil that drains well. Keep an eye on the weather forecast; we can sometimes get a late frost, even in late May. A frost blanket can protect your young plants if needed. Many Midwest gardeners opt to buy potted mums in the fall or starts in the spring to skip the seed-starting process altogether.

Chrysanthemums need consistent moisture, but overwatering can be just as harmful as underwatering, especially with our moderate-to-humid summers here in the Midwest. Water deeply at the base of the plant, aiming to keep the soil consistently moist but not soggy. Avoid overhead watering, as wet foliage can encourage fungal diseases.

During the hotter parts of the summer, you might need to water every few days. Stick your finger about two inches into the soil; if it feels dry, it's time to water. Aim for about an inch of water per week, either from rainfall or irrigation. Yellowing leaves can indicate overwatering, while wilting leaves signal underwatering. A layer of mulch around the base of the plants helps retain moisture and regulate soil temperature, which is helpful during our summer heat spells.

Pinching your chrysanthemums is key to getting a full, bushy plant covered in blooms. Pinch off the growing tips every 2-3 weeks until around July 4th. This encourages the plant to branch out and produce more flowering stems.

After July 4th, stop pinching to allow flower buds to form. As the season winds down and the first frost approaches around mid-September, you can cut back the plant to tidy it up.

You can expect your first chrysanthemum blooms in late July through mid-September, depending on the variety and when you transplanted. The flowers last for weeks in the garden, providing a long-lasting display of color.

Cut the stems for bouquets when the flowers are fully open. To encourage continued production, deadhead (remove) spent flowers regularly. As the first frost approaches in mid-September, harvest any remaining blooms to enjoy indoors.

Chrysanthemums are generally easy to grow, but they can be susceptible to a few common pests and diseases in the Midwest.

Aphids *What it looks like:* Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth. *What causes it:* Rapidly 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:* Visible tunnels or trails inside the leaves. Leaves may appear distorted or blotchy. *What causes it:* The larvae of small flies that burrow into the leaves to feed. *How to fix/prevent it:* Remove and destroy infested leaves. Use floating row covers to prevent adult flies from laying eggs on the plants. Insecticidal soap or neem oil can help control infestations.

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 heat and moderate-to-humid humidity during the summer can create ideal conditions for spider mites and rust. Be vigilant about monitoring your plants, especially during periods of drought stress or high humidity, and take action quickly to prevent infestations and diseases from spreading.

Chrysanthemums make great companions for several plants in your Midwest garden. Tomatoes and peppers benefit from chrysanthemums because the mums help repel aphids and other pests that can damage these crops. Lettuce also enjoys the shade provided by the bushy growth habit of chrysanthemums, especially during the summer heat spells we sometimes get. Avoid planting chrysanthemums near anything in the cabbage family (broccoli, kale, etc.) as they can attract similar pests.