Geranium in Zone 4A — Midwest

Geraniums offer a vibrant splash of color to your Midwest garden, and their versatility extends beyond just aesthetics. They thrive in containers, borders, and even hanging baskets, bringing beauty to your outdoor spaces all summer long. Plus, their fragrance is a welcome addition, especially on those mild summer nights we cherish here.

The Midwest weather can be unpredictable, with its variable spring and summer heat spells, but don't let that deter you. Starting geraniums at the right time and providing proper care will reward you with beautiful blooms throughout our 128-day growing season.

Starting geraniums from seed indoors is doable, but honestly, they are very slow to get going. If you're up for a challenge and want to save a bit of money, go for it. Otherwise, buying starts from a local nursery is the easiest route.

If you decide to start seeds, aim for late February through mid March, about 12 weeks before you plan to transplant them outdoors. Use seed trays with a good seed-starting mix, provide warmth (a heat mat is helpful), and ensure they get plenty of light, either from a sunny window or a grow light. Bottom watering is your friend here; it helps prevent damping-off. Given our moderate-to-late spring, getting a head start indoors is essential for early blooms.

Wait until late May through late June to transplant your geraniums outdoors. This is after the risk of frost has passed, which is a must in our Zone 4A Midwest gardens. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week.

Space them 10-12 inches apart to allow for good air circulation. Keep an eye on the weather forecast around transplant time; unexpected cold snaps can still happen, so be ready to cover them if needed. Geraniums are very slow from seed, so remember that buying starts is the easiest way to enjoy them.

Geraniums need moderate watering, but they definitely don't like soggy feet. In the Midwest, with our wet-summer rainfall and moderate-to-humid conditions, it's crucial to let the soil dry slightly between waterings. Overwatering can quickly lead to stem rot, a common issue in our region.

During the active growing season, especially during those summer heat spells, aim to water about 1 inch per week, either from rainfall or supplemental watering. Use the finger test: stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Try to water at the base of the plant to avoid getting the foliage wet, which can encourage fungal diseases in our humid climate.

Signs of underwatering include wilting leaves and dry, cracked soil. Overwatering, on the other hand, can manifest as yellowing leaves and mushy stems. A layer of mulch can help retain moisture and regulate soil temperature, which is particularly beneficial during our fluctuating Midwest weather.

Pruning geraniums is simple but essential for keeping them blooming all season long. The key is to deadhead spent flower clusters regularly. This encourages the plant to produce more blooms rather than putting energy into seed production.

Simply snip off the faded flowers just below the flower head. If you notice any leggy stems, pinch them back to encourage bushier growth. As the first frost approaches around mid- September in the Midwest, you can stop deadheading to allow the plant to prepare for dormancy, or bring indoors to overwinter.

Since geraniums are primarily grown for their ornamental value, "harvesting" is a bit different. You'll be enjoying their blooms from early August through mid September, depending on when you transplanted them. The best sign of "readiness" is simply when the flowers are fully open and vibrant.

To encourage continued production, keep deadheading those spent flowers. This keeps the plant looking neat and directs its energy toward producing new blooms. As the first frost looms in mid- September in the Midwest, it's time to consider bringing your geraniums indoors if you want to overwinter them. Otherwise, enjoy their last flush of color before the season ends.

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

Botrytis Blight

• What it looks like: Grayish-brown mold on leaves, stems, and flowers.
• What causes it: High humidity and poor air circulation, common during our wet-summer rainfall periods.
• How to fix/prevent it: Provide good air circulation by spacing plants properly. Remove affected leaves and flowers promptly. Avoid overhead watering, especially in the evening. Fungicides can be used as a last resort.

Geranium Budworm

• What it looks like: Holes in buds and flowers, chewed leaves, and small green caterpillars.
• What causes it: Moths laying eggs on the plant.
• How to fix/prevent it: Handpick caterpillars when you see them. Bacillus thuringiensis (Bt) is an effective organic control. Regularly inspect your plants for signs of infestation.

Edema

• What it looks like: Small, water-soaked blisters on the undersides of leaves.
• What causes it: Overwatering and poor air circulation, leading to cells bursting.
• How to fix/prevent it: Improve drainage and air circulation. Avoid overwatering and allow the soil to dry slightly between waterings. Ensure plants have adequate sunlight.

Midwest Specific Challenges: Our moderate-to-hot heat, moderate-to-humid humidity, and wet-summer rainfall create conditions that can favor fungal diseases like botrytis blight and edema. Careful watering practices and good air circulation are essential for keeping your geraniums healthy in the Midwest.

Geraniums make great companions for several plants in the Midwest garden. Tomatoes, peppers, and corn benefit from geraniums because they repel certain pests, like Japanese beetles, that can damage these crops. Roses also appreciate having geraniums nearby, as they can help deter aphids. Avoid planting geraniums near fennel, as fennel can inhibit their growth.