Geranium in Zone 5A — Great Plains

Geraniums are a classic choice for Plains gardens, offering vibrant color and fragrance all summer long. Their heat tolerance is a real asset here, and the bright blooms are a welcome sight against our sometimes-stark prairie landscapes. Plus, they attract pollinators, boosting the health of your entire garden.

Our growing season can be a bit of a rollercoaster with extreme weather, but don't let that scare you off. With a 168-day growing season, and by getting a head start indoors or buying established plants, you can absolutely enjoy beautiful geraniums.

Starting geraniums from seed indoors is possible, but be warned: they're slow growers. If you're up for the challenge, begin in early to late February, about 12 weeks before you plan to transplant outdoors. Use seed trays with a good seed-starting mix, and keep them warm – around 70-75°F is ideal.

Bottom watering is a great way to keep the soil consistently moist without damping off the seedlings. Place the tray in a shallow container of water and let the soil absorb what it needs. Given our variable spring weather, having these indoors gives you a buffer against any late frosts or temperature swings.

Transplant your geraniums outdoors from early May through early June, once the risk of frost has passed. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space them 10-12 inches apart to allow for good air circulation. Honestly, given our short season and the slow growth from seed, buying established geranium starts from a local nursery is often the easiest route. You'll get blooms sooner, and they'll be better equipped to handle the Plains' weather.

Geraniums like moderate watering, but they definitely don’t like soggy soil. Let the soil dry out slightly between waterings. Stick your finger about two inches deep into the soil – if it feels dry, it’s time to water.

During our hot summer months, you might need to water deeply a couple of times a week, giving them about an inch of water each time. Water at the base of the plant to avoid wetting the foliage, especially with our low-to-moderate humidity. Overhead watering can lead to fungal issues.

Signs of underwatering include wilting leaves and dry, crispy edges. Overwatering can cause yellowing leaves and stem rot. A good layer of mulch, like shredded bark, helps retain moisture and keeps the soil temperature consistent, which is especially helpful during our extreme temperature swings.

Deadheading is key to keeping your geraniums blooming all season long. Simply pinch off the spent flower clusters just below the flower head. This encourages the plant to produce more blooms instead of putting energy into seed production.

If your geraniums start to look leggy – meaning they have long, bare stems – you can pinch back the stems to encourage bushier growth. Do this anytime during the growing season. As the first frost approaches in early October, you can bring your geraniums indoors to overwinter, or simply let them go.

Geraniums aren't really "harvested" in the traditional sense, but you do harvest their beauty all season long. You can expect your first blooms starting in mid-July and continuing through early September. The key is to remove faded blooms regularly.

This not only keeps the plants looking tidy but also encourages continuous flowering. Simply pinch off the spent flower heads where they meet the stem. As the first frost approaches in early October, you can take cuttings to propagate new plants indoors over winter, ensuring you have geraniums to enjoy next year.

Geraniums can face a few problems in our region, but being vigilant can help.

Botrytis Blight

• What it looks like: Gray mold on leaves, stems, and flowers, especially in damp conditions.
• What causes it: Fungal disease favored by cool, wet weather and poor air circulation. In the Plains, this is often a problem during periods of high humidity after a storm.
• How to fix/prevent it: Remove infected plant parts immediately. Improve air circulation by spacing plants properly. Avoid overhead watering.

Geranium Budworm

• What it looks like: Holes in buds and flowers, often with dark droppings nearby.
• What causes it: Caterpillars that feed on geranium buds and flowers.
• How to fix/prevent it: Handpick caterpillars off plants. Use insecticidal soap or Bacillus thuringiensis (Bt) as a last resort.

Edema

• What it looks like: Small, blister-like bumps on the undersides of leaves, which can turn brown and corky.
• What causes it: Overwatering combined with cool temperatures and high humidity. The plant takes up water faster than it can transpire.
• How to fix/prevent it: Improve drainage, water less frequently, and ensure good air circulation.

Great Plains Specific Challenges: Our combination of hot heat, low-to-moderate humidity, and variable rainfall can stress geraniums. Be especially mindful of watering practices, ensuring good drainage to prevent stem rot. Wind protection is also essential to prevent damage to the plants and flowers.

Geraniums make great companions for several plants in the Plains garden. Planting them near tomatoes and peppers can help deter certain pests, like aphids, due to their strong scent. They also work well near corn, helping to attract beneficial insects that prey on corn pests. Roses benefit from geraniums as well, as they help deter Japanese beetles. Avoid planting geraniums near fennel, as it can inhibit their growth.