Geranium in Zone 4B — Midwest

Geraniums bring a classic touch to Midwest gardens, adding vibrant color and fragrance all summer long. They're perfect for containers, borders, and even window boxes, offering a cheerful display that thrives in our fertile soil and warm summer days. Plus, deadheading them is a relaxing way to spend an afternoon in the garden.

While Midwest weather can be unpredictable, especially with our variable springs and occasional summer heat spells, starting geraniums indoors or buying transplants ensures you get a head start. Our 138-day growing season is just right for these beauties to flourish, offering a satisfying reward for your efforts.

Starting geraniums from seed indoors is possible, but honestly, it's a slow process. If you're up for a challenge, start seeds indoors from late February through mid-March. This gives them about 12 weeks to get a good start before our typical transplanting window.

Use seed trays with a good seed-starting mix. Keep them warm (around 70-75°F) and provide plenty of light with grow lights. Bottom watering is a great trick to keep the soil consistently moist without overwatering the delicate seedlings. Given our moderate-to-late springs here in the Midwest, this head start can be crucial.

For most of us in the Midwest, buying geranium starts from a local nursery is the way to go. But if you've started your own, or you just want to give them a good home, transplant them outdoors from late May through late June, once the risk of frost has passed.

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Plant them 10-12 inches apart in well-drained soil. Keep an eye on the weather forecast around transplant time; a late cold snap can still happen, so be ready to cover them if needed.

Geraniums need moderate watering, and while they can tolerate some heat, they're not drought-tolerant. Here in the Midwest, with our wet summers and moderate-to-humid conditions, it's essential to avoid overwatering.

During the hotter parts of summer, you might need to water every few days, especially if they're in containers. Use 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 your hose. 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 soil. Overwatering can lead to yellowing leaves and potentially stem rot. A good layer of mulch, like shredded bark, can help retain moisture and regulate soil temperature, which is helpful during our summer heat spells.

Deadheading is key to keeping your geraniums blooming all season long. Simply pinch or snip off the spent flower clusters just below the flower head. This encourages the plant to put its energy into producing new blooms.

Throughout the growing season, pinch back any leggy stems to encourage a bushier, more compact growth habit. As we approach the first frost in late September, stop deadheading to allow the plant to prepare for dormancy.

While you don't "harvest" geraniums in the traditional sense, the time to enjoy their blooms is from early August through mid-September. The 70 days to maturity is really just a guide for when you can expect the first flush of flowers.

The real harvest is the continuous display of colorful flowers throughout the summer. Keep deadheading those faded blooms to encourage more to come. As the end of the season approaches and the first frost threatens in late September, you can bring your potted geraniums indoors to overwinter, or take cuttings to propagate new plants for the following year.

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, often starting with water-soaked spots.
• What causes it: High humidity and poor air circulation, common during our wet summers.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning out affected areas. Avoid overhead watering and apply a fungicide if necessary.

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 plants, with the larvae feeding on the buds and flowers.
• How to fix/prevent it: Handpick caterpillars, use insecticidal soap or Bacillus thuringiensis (Bt), and monitor plants regularly.

Edema

• What it looks like: Small, blister-like bumps on the undersides of leaves, which can turn brown or yellow.
• What causes it: Excessive moisture in the soil and cool temperatures, especially during our variable spring weather.
• How to fix/prevent it: Improve drainage, avoid overwatering, and provide good air circulation.

Midwest Specific Challenges: Our moderate-to-hot summers with moderate-to-humid humidity and wet-summer rainfall can create ideal conditions for fungal diseases like botrytis blight. It's crucial to provide good air circulation and avoid overwatering to keep your geraniums healthy.

Geraniums make great companions for several plants in the Midwest garden:

• Tomatoes, peppers, and corn: Geraniums are said to repel certain pests, like tomato hornworms, that can damage these crops. The strong scent may confuse the pests, making it harder for them to find their preferred hosts.
• Roses: Geraniums can help deter Japanese beetles from roses, protecting their delicate blooms.

Avoid planting geraniums near:

• (None specified)