Geranium in Zone 5A — Mountain West

Geraniums bring a vibrant splash of color to our Mountain gardens, thriving even with our intense sun. Their cheerful blooms and easy care make them a rewarding choice for filling beds, borders, and containers. Plus, those cool nights we get even in summer help intensify their fragrance and color, making them even more enjoyable.

Our short growing season and alkaline soil can present challenges, but with proper timing and soil preparation, you can enjoy beautiful geraniums all summer long. Knowing that we're working with a roughly 138-day growing season, we can plan accordingly to get the most from these beauties.

Starting geraniums from seed indoors is possible, but be prepared for a slow process. If you want to give it a try, begin in late February through mid March, about 12 weeks before you intend to transplant them outdoors. Use seed trays with a good seed-starting mix, provide warmth (a heat mat helps), and ensure they get plenty of light, especially with our intense high-altitude sun.

Bottom watering is a great way to keep the seedlings evenly moist without overwatering, which can be a problem. Remember, spring here in the Mountains can be late and unpredictable, so be patient and don't rush the process. Honestly, though, you might find it easier to buy starts from a local nursery – geraniums are notoriously slow from seed.

Transplant your geraniums outdoors in late May through late June, once the danger of frost has passed. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to our intense Mountain sun and cooler temperatures.

Space them 10-12 inches apart in well-draining soil. Even in late spring, we can still get unexpected cold snaps or even hail, so keep an eye on the forecast and be prepared to cover them if needed. As I mentioned, geraniums are slow from seed – buying starts is often the easiest way to get a jump on the season.

Geraniums need moderate watering, but they definitely don't like soggy soil. In our dry Mountain climate, the key is to find the right balance. Let the soil dry out slightly between waterings to prevent stem rot, which can be a real issue.

During the hottest part of the summer, you'll likely need to water them a couple of times a week, providing about an inch of water each time. Use the finger test: stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Water at the base of the plant to avoid wetting the foliage, as our low humidity doesn't always dry leaves quickly, and that can encourage fungal issues.

Signs of underwatering include wilting leaves and dry, cracked soil. Overwatering can cause yellowing leaves and mushy stems. A good layer of mulch around the base of the plants will help retain moisture and keep the soil cooler, which is especially helpful in our intense sun.

Deadheading is essential for keeping your geraniums blooming throughout the season. Simply pinch or snip off the spent flower clusters as soon as they start to fade. This encourages the plant to put its energy into producing new blooms instead of setting seed.

Throughout the summer, you can also pinch back any leggy stems to encourage a bushier, more compact growth habit. As we approach the end of the season in late September, with the threat of the first frost looming, you can give your geraniums a final pruning to tidy them up.

While you don't "harvest" geraniums in the traditional sense, you can expect to enjoy their blooms from early August through mid September. The 70 days to maturity refers to bloom time after transplant. The real harvest is the visual beauty they bring to your garden.

The key is to remove faded blooms regularly to maintain a neat appearance and encourage continuous flowering. Simply snip off the entire flower stalk at the base of the plant. This not only keeps the plant looking tidy but also prevents it from wasting energy on seed production.

As frost threatens in late September, you can bring your geraniums indoors to overwinter them, or take cuttings to propagate new plants for next year. Even if you don't overwinter them, enjoy their vibrant color right up until the first hard freeze.

Here are a few common problems to watch out for with geraniums in our Mountain West gardens:

Botrytis Blight

• What it looks like: Grayish-brown mold on leaves, stems, and flowers, often appearing after periods of wetness.
• What causes it: A fungal disease that thrives in cool, damp conditions. While our humidity is generally low, we can get occasional wet spells, especially during spring and fall.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning out crowded growth. Remove and destroy any infected plant parts. Avoid overhead watering, and consider using a fungicide if the problem is severe.

Geranium Budworm

• What it looks like: Small holes in flower buds and petals, often with dark droppings nearby. You might also find small caterpillars inside the buds.
• What causes it: These caterpillars are the larvae of moths that lay their eggs on geraniums. They feed on the buds and flowers, causing significant damage.
• How to fix/prevent it: Inspect your plants regularly for signs of budworms. Handpick any caterpillars you find. You can also use Bacillus thuringiensis (Bt), a biological insecticide, to control them.

Edema

• What it looks like: Small, blister-like bumps on the undersides of leaves. These bumps can eventually turn brown and corky.
• What causes it: Edema is caused by an imbalance of water uptake and transpiration, often occurring when the soil is too wet and the air is humid.
• How to fix/prevent it: Improve drainage by planting in well-draining soil. Avoid overwatering, and provide good air circulation.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity generally benefit geraniums, as they tolerate heat better than many flowers and are less prone to fungal diseases. However, our intense sun can sometimes scorch the leaves, so providing some afternoon shade can be helpful. The dry rainfall means you'll need to be diligent about watering, but be careful not to overwater, especially in heavy clay soils.

Geraniums make great companions for several plants in our Mountain gardens. They are said to deter certain pests, benefiting:

• Tomatoes and Peppers: Geraniums can help repel tomato hornworms and other pests that attack these vegetables.
• Corn: Planting geraniums near corn may help deter corn earworms.
• Roses: Geraniums can help repel Japanese beetles, which can be a nuisance on roses.

I'd recommend avoiding planting them near:

• — (no specific bad companion plants to list)