Geranium in Zone 3B — Mountain West

Geraniums are worth growing in our short Mountain West summers for their vibrant colors and long bloom period. Their cheerful blossoms brighten up patios and gardens, and their scent repels some common garden pests. Plus, the cool nights even in summer seem to intensify their colors!

Starting geraniums from seed can be tricky with our short growing season (about 108 days). However, choosing the right varieties and starting early indoors will give you a head start. Or, buying established starts from your local nursery is always a great option for high altitude gardening.

You can start geranium seeds indoors to get a jump on our short growing season, but be aware they are very slow to grow from seed. If you want to try starting your own, aim for early to late March, about 12 weeks before you intend to transplant them outdoors.

Use seed trays with a good seed-starting mix. Keep the soil consistently moist, but not soggy; bottom watering works well. Geraniums need plenty of light, so a sunny windowsill or grow lights are essential. Remember that spring can be slow to arrive here, so be patient!

Transplant your geraniums outdoors in early to mid June, once the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cool nights.

Plant them 10-12 inches apart in well-draining soil. Keep an eye on the weather forecast – late frosts are not unheard of even in June in the Mountain West. If a frost threatens, be ready to cover your young plants. Honestly, buying established starts from a local nursery is the easiest way to go with geraniums in our short season.

Geraniums need moderate watering, but they definitely don't like soggy feet. Let the soil dry slightly between waterings. In our dry Mountain West climate, overwatering is a much bigger risk than underwatering, as it can lead to stem rot.

During the hottest part of the summer, you might need to water every few days. Use the "finger test" – 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, watering at the base of the plant to avoid getting the foliage wet.

Signs of underwatering include wilting leaves and dry, cracked soil. Overwatering can cause yellowing leaves and mushy stems. A light layer of mulch around your plants will help retain moisture and keep the soil cool, which is helpful even with our moderate summer heat.

Deadheading is key to keeping your geraniums blooming throughout the season. Simply pinch or cut off the spent flower clusters just below the flower head. This encourages the plant to put its energy into producing new blooms instead of seeds.

If your geraniums become leggy, pinch back the stems to encourage bushier growth. You can do this anytime during the growing season. As the first frost approaches in early September, stop deadheading to allow the plant to harden off for the winter, if you're overwintering indoors.

Geraniums are grown for their beautiful flowers, so "harvesting" simply means enjoying their beauty in your garden. Expect your first blooms from mid August through early September, if you started from seed, but earlier if you bought starts.

Remove faded blooms regularly to keep the plants looking tidy and to encourage more flowers. Cut the flower stems just above a leaf node.

As the first frost threatens in early September, you can bring your geraniums indoors to overwinter them. Cut them back by about a third and place them in a cool, bright location. Water sparingly during the winter months.

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, humid conditions. Although our humidity is low, overhead watering or poor air circulation can create a favorable environment.
• How to fix/prevent it: Water at the base of the plant, provide good air circulation, and remove any infected plant parts immediately. A fungicide may be necessary in severe cases.

Geranium Budworm

• What it looks like: Holes in flower buds and leaves. You might also see small green caterpillars.
• What causes it: These caterpillars feed on geraniums. They're more common in warmer months.
• How to fix/prevent it: Handpick the caterpillars off the plants or use an insecticide labeled for budworms. Regularly inspect your plants for signs of infestation.

Edema

• What it looks like: Small, blister-like bumps on the undersides of leaves.
• What causes it: Edema is caused by inconsistent watering, especially when the soil stays too wet. The cells in the leaves burst from excess water.
• How to fix/prevent it: Ensure good drainage, avoid overwatering, and provide consistent watering. Our cool nights can exacerbate this problem if the soil is too wet.

Mountain West Specific Challenges: Our moderate-at-altitude summer heat is usually well-tolerated by geraniums, but our intense UV radiation can sometimes scorch the leaves. The low humidity helps prevent many fungal diseases, but it also means you need to be vigilant about watering. Our alkaline soil can also be a challenge; amend your soil with compost to improve its pH and drainage.

Geraniums make good companions for several plants in the Mountain West garden:

• Tomatoes: Geraniums are said to repel tomato hornworms, a common pest in our gardens.
• Peppers: Like tomatoes, peppers can benefit from the pest-repelling properties of geraniums.
• Corn: Geraniums can help deter some corn pests.
• Roses: Geraniums are often planted near roses to deter Japanese beetles.

Avoid planting geraniums near fennel, as it can inhibit their growth.