Geranium in Zone 7A — Northern California

Geraniums are a fantastic addition to any Northern California garden. Their vibrant blooms add cheerful color, and they're relatively low-maintenance, fitting right into our water-wise gardening ethos. Plus, they attract beneficial pollinators, making your garden a more thriving ecosystem.

While we NorCal gardeners face challenges like drought and summer heat, geraniums can thrive with proper care and attention to watering. Our long growing season, often stretching from mid-March all the way into early November, gives you plenty of time to enjoy their blooms.

Starting geraniums from seed indoors is possible, but be warned: they are slow growers! If you're eager to get a jump start, aim to sow your seeds indoors from early to late January, roughly 12 weeks before you plan to transplant them outdoors. This gives them a head start before our early spring arrives.

Use seed trays with a good quality seed-starting mix. Keep the soil consistently moist (bottom watering is great for this) and provide a warm environment with plenty of light. A sunny windowsill might work, but supplemental grow lights will give you better results.

Honestly, unless you're a very patient gardener, you'll probably have better luck and faster blooms by purchasing established geranium starts from a local nursery in early spring.

Once the danger of frost has passed – typically from early April through early May in our region – and your geranium seedlings have developed several sets of true leaves, it's time to transplant them outdoors. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week.

Choose a sunny spot with well-draining soil and space your plants about 10-12 inches apart. Be mindful of potential late frosts in early spring; keep an eye on the weather forecast and be prepared to cover your young plants if needed. Established nursery starts are better equipped to handle the temperature swings.

Watering geraniums properly is key, especially during our dry summers. While they aren't drought-tolerant, they also don't like soggy feet. A good rule of thumb is to let the top inch or two of soil dry out between waterings. Stick your finger in the soil to check!

During the hotter months (June through August), you'll likely need to water them a couple of times a week, providing about an inch of water each time. In spring and fall, when temperatures are milder, you can reduce watering frequency. Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our climate.

Signs of underwatering include wilting leaves and dry, cracked soil. Overwatering, on the other hand, can lead to yellowing leaves and stem rot. Mulching around your geraniums with organic matter like compost helps retain moisture in the soil and reduce the need for frequent watering.

Regular pruning, or rather deadheading, is crucial for keeping your geraniums blooming throughout the season. Simply pinch off the spent flower clusters as they fade. This encourages the plant to produce more flowers instead of putting energy into seed production.

If your geraniums become leggy or overgrown, you can pinch back the stems to encourage bushier growth. Do this anytime during the growing season. As the first frost approaches in early November, you can cut back your geraniums to tidy them up, but don't prune them too severely at this time.

Geraniums aren't exactly "harvested" in the traditional sense. You won't be eating them! Instead, you'll enjoy their beauty as ornamental flowers throughout the growing season. Expect your first blooms to appear from mid-June through late July, about 70 days after transplanting.

The "harvest" is really about maintaining the plant's appearance and encouraging continued blooming. Regularly remove faded or dead flowers to keep the plant looking tidy and to promote more flower production.

As the weather cools down in the fall and the first frost approaches (typically around early November in our region), your geraniums will naturally slow down their flowering. You can either bring them indoors to overwinter or let them die back naturally.

Here are a few common problems you might encounter with geraniums in Northern California:

Botrytis Blight

• What it looks like: Gray mold on flowers, leaves, and stems.
• What causes it: High humidity and poor air circulation. While we have low humidity, morning fog in some microclimates can create favorable conditions.
• How to fix/prevent it: Remove infected plant parts promptly. Improve air circulation by spacing plants adequately and avoiding overhead watering. Fungicides can be used as a last resort.

Geranium Budworm

• What it looks like: Holes in flower buds and leaves, often with caterpillars present.
• What causes it: These caterpillars feed on geraniums.
• How to fix/prevent it: Handpick caterpillars or use Bacillus thuringiensis (Bt), a biological insecticide. Monitor plants regularly for signs of infestation.

Edema

• What it looks like: Small, raised blisters or bumps on the undersides of leaves.
• What causes it: Excessive moisture in the soil combined with cool temperatures and high humidity.
• How to fix/prevent it: Improve drainage by planting in well-draining soil. Avoid overwatering, especially during cool weather.

Northern California Specific Challenges: Our moderate-to-hot summers can stress geraniums if they aren't properly watered. While our low humidity is generally beneficial, microclimates with morning fog can increase the risk of fungal diseases. Consistent monitoring and proper watering practices are key to keeping your geraniums healthy and thriving in our unique climate.

Geraniums make great companions for a variety of plants in your Northern California garden.

• Tomatoes, peppers, and corn: Geraniums are said to repel certain pests, such as tomato hornworms and aphids, that can plague these vegetables.
• Roses: Geraniums can help protect roses from Japanese beetles.

Avoid planting geraniums near:

• (No significant bad companions)