Geranium in Zone 4B — Mountain West

Geraniums are a classic choice for adding vibrant color to our Mountain West gardens, and for good reason. Their cheerful blooms brighten up containers, beds, and borders, lasting right up until frost. Plus, their fragrance is a welcome addition to any outdoor space.

Growing anything in our high-altitude, short-season climate presents unique challenges. Our intense sun and cool nights demand careful planning. But with a little attention to timing, you can absolutely enjoy beautiful geraniums all summer long. We're working with a roughly 128-day growing season here, so let's make the most of it.

Starting geraniums from seed indoors is possible, but be warned: they are notoriously slow growers. You have about a 3-week window from late February through mid March to get your seeds started indoors, roughly 12 weeks before you'll be able to transplant them outside. If you want to try it, sow seeds in seed trays filled with a good seed-starting mix.

Keep the trays warm, ideally around 70-75°F, and provide plenty of light – a grow light is best, given our late spring starts. Bottom watering can help prevent damping off and keep the seedlings consistently moist. Honestly, given our short season and the slow growth of geraniums from seed, many of us here in the Mountain West find it easier to buy established starts from a local nursery.

Transplanting geraniums outdoors should happen from late May through late June, once all danger of frost has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This is crucial to prevent shock from our intense UV light.

Choose a spot with full sun to partial shade and space your plants 10-12 inches apart. Our weather can be unpredictable in late spring, so keep an eye on the forecast. A late frost or hailstorm can set your geraniums back, so be prepared to cover them if necessary. Starting with healthy transplants is definitely the easiest way to get a jump start in our short growing season.

Watering is key to keeping your geraniums happy in our dry Mountain West climate. While they need moderate watering, overwatering is a common mistake that can lead to stem rot. The key is to let the soil dry out slightly between waterings.

During the hottest part of the summer, you'll likely need to water your geraniums every few days. 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 slowly at the base of the plant to avoid wetting the foliage. Overhead watering isn't ideal in our region, even with low humidity, as it can still encourage fungal diseases.

Signs of underwatering include wilting leaves and dry, crispy edges. Overwatering, on the other hand, can cause yellowing leaves and mushy stems. A layer of mulch around the base of your plants can help retain moisture and keep the soil cool, which is especially helpful during our hot summer days.

Deadheading is essential for 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.

Throughout the summer, you can also pinch back any leggy stems to promote bushier growth. Use your fingers or clean pruning shears to snip the stems just above a leaf node. As the first frost approaches in mid- September, stop deadheading. This allows the plant to set seed, which can help it survive the winter if you're trying to overwinter it indoors (though that's tough in our climate).

While you're not "harvesting" geraniums for food, you are harvesting their beauty all season long. Expect your first blooms to appear from early August through mid September, depending on when you transplanted your starts. The key is to enjoy them as garden flowers.

Regularly remove any faded or dead blooms to keep the plants looking neat and encourage continued flowering. Simply pinch or snip off the spent flowers at the base of the stem. As the first frost approaches in mid- September, you can bring your geraniums indoors to try and overwinter them, though success is not guaranteed in our climate. Cut them back significantly before bringing them inside.

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

Botrytis Blight

• What it looks like: Gray mold on flowers, leaves, and stems.
• What causes it: This fungal disease thrives in cool, moist conditions. While our region is generally dry, periods of rain or overwatering can create favorable conditions.
• How to fix/prevent it: Improve air circulation by spacing plants properly. Avoid overhead watering. Remove and destroy any infected plant parts immediately.

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, causing damage to buds and foliage.
• How to fix/prevent it: Inspect plants regularly for signs of budworms. Handpick them off the plants or use an appropriate 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 excessive moisture in the soil and cool temperatures. This can happen during periods of heavy rain or if the soil is not draining well.
• How to fix/prevent it: Improve drainage by amending the soil with compost. Avoid overwatering. Ensure good air circulation around the plants.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity generally help to keep fungal diseases at bay, but it's still important to be vigilant. The intense sun can also scorch leaves if plants are not properly hardened off or if they are not getting enough water.

Geraniums make great companions for several plants in the Mountain West garden. They are said to repel certain pests that can bother tomatoes, peppers, and corn, making them a welcome addition to your vegetable garden. Geraniums also pair well with roses, as they can help deter Japanese beetles. I'd avoid planting them near cucurbits; the strong scent of geraniums can mask the cucurbit scent that attracts pollinators.