Geranium in Zone 4A — Mountain West

Geraniums are a fantastic addition to any Mountain West garden. Their vibrant colors brighten up our landscape, and their blooms last well even with our intense sun. Plus, the cool nights we get here enhance their fragrance, making them even more enjoyable.

Growing geraniums in our Zone 4A Mountain climate does present some challenges. We have a short 118-day growing season, and our high altitude and intense UV can be tough on plants. But with the right timing and a little extra care, you can successfully grow beautiful geraniums.

Starting geraniums from seed indoors is an option, but be aware that they are very slow to get going. If you're up for a patient approach, start your seeds indoors in early to late March, about 12 weeks before you plan to transplant them outside.

Use seed trays with a good seed-starting mix and provide consistent warmth and light. Bottom watering is a great way to keep the soil evenly moist without disturbing the delicate seedlings. Remember, spring in the mountains can be slow to arrive, so don't rush the process.

Transplant your geraniums outdoors in early to late 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 intense Mountain sun and cooler nights.

Plant them 10-12 inches apart in a sunny location. Keep an eye on the weather. Even in June, we can get unexpected cold snaps or even hail, so be prepared to cover your young plants if necessary. Honestly, for easiest results, consider buying established starts from a local nursery. They'll be better acclimated to our conditions.

Watering geraniums correctly is key to success in our dry Mountain climate. While they need moderate moisture, overwatering is a common problem that can lead to stem rot. Let the soil dry slightly between waterings.

During the hotter parts of summer, you'll likely need to water a few times a week, but always check the soil first. 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, delivered at the base of the plant to avoid wetting the foliage, which can encourage disease in our low-humidity environment.

Watch for signs of underwatering, like wilting leaves, or overwatering, like yellowing leaves. A layer of mulch around your plants can help retain moisture and keep the soil temperature more consistent.

Pruning geraniums is simple and helps keep them blooming all season long. The main thing you'll want to do is deadhead spent flower clusters. This encourages the plant to produce more blooms instead of putting energy into seed production.

Simply snip off the faded flower heads just below the point where they connect to the stem. You can also pinch back any leggy stems to encourage bushier growth. Do this throughout the growing season. As the first frost approaches in mid- September, stop deadheading to allow the plant to prepare for dormancy.

Geraniums are grown for their beautiful flowers, so your harvest is really just enjoying them in your garden. You can expect your geraniums to start blooming in mid-August through mid-September, about 70 days after transplanting.

Remove faded blooms regularly to keep the plants looking tidy and to encourage continuous flowering. There's no specific sign of "ripeness" to look for – just enjoy the blooms as they come! As the weather cools and the first frost approaches in mid- September, you can bring potted geraniums indoors to overwinter, or simply enjoy the last blooms before the season ends.

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

Botrytis Blight

• What it looks like: Gray mold on leaves, stems, and flowers.
• What causes it: This fungal disease thrives in cool, moist conditions. While our humidity is low, overwatering or poor air circulation can create a favorable environment, especially during cooler nights.
• How to fix/prevent it: Improve air circulation by spacing plants properly. Avoid overhead watering. Remove and destroy infected plant parts immediately.

Geranium Budworm

• What it looks like: Holes in buds and flowers, often with small green caterpillars present.
• What causes it: These caterpillars feed on buds and flowers, causing damage and preventing blooms.
• How to fix/prevent it: Inspect plants regularly for caterpillars. Handpick them off and destroy them. Consider using Bacillus thuringiensis (Bt), a biological insecticide, if the infestation is severe.

Edema

• What it looks like: Small, blister-like bumps on the undersides of leaves.
• What causes it: Edema is caused by an imbalance in water uptake and transpiration, often due to cool temperatures and high soil moisture.
• How to fix/prevent it: Improve air circulation and drainage. Avoid overwatering, especially during cool periods. Make sure your plants are getting enough sunlight.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall generally help to keep fungal diseases at bay, but the intense sun can still stress plants. Be sure to provide adequate water and some afternoon shade during the hottest part of the day.

Geraniums make good companions for several plants in the Mountain West garden. They deter pests like cabbage moths, making them great companions for tomatoes, peppers, and corn. They also complement roses beautifully, deterring Japanese beetles and adding a touch of color to your rose garden.

Avoid planting geraniums near fennel, as fennel can inhibit their growth. Otherwise, geraniums are generally easygoing and get along well with most other plants.