Geranium in Zone 8B — Desert Southwest

Geraniums are a classic for a reason: their vibrant colors and delightful fragrance make them a rewarding addition to any Desert Southwest garden. They're versatile, thriving in containers or in the ground, and bring a cheerful pop of color during our two growing seasons. Plus, they attract beneficial pollinators to your garden.

While our extreme heat and arid conditions present challenges, the timing of planting Geraniums allows them to flourish during the milder parts of our long, 279-day growing season. Starting early and paying attention to watering will set you up for success.

Starting Geraniums from seed indoors is possible, but be warned, they are slow growers. If you're feeling ambitious, begin in early to late December, giving them about 12 weeks to develop before transplanting.

Use seed trays with a well-draining seed-starting mix. Keep the soil consistently moist by bottom watering to avoid disturbing the tiny seeds and provide warmth and bright light, ideally with a grow light. Remember, our very-early spring means you'll need to be ready to transplant sooner than gardeners in other regions.

Transplant your Geranium seedlings outdoors from mid March through early April. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense Desert Southwest sun and temperature swings.

Space the plants 10-12 inches apart in well-draining soil. Honestly, for the easiest results, consider purchasing established starts from a local nursery. They'll be better equipped to handle our conditions right away.

Watering is critical for Geraniums in our arid climate. While they need moderate moisture, overwatering is a quick path to stem rot. Let the top inch or two of soil dry out between waterings. Use the finger test – if the soil feels dry about 2 inches down, it's time to water.

During the hot spring and fall growing seasons, you'll likely need to water deeply about 1-2 times per week, providing about 1 inch of water each time. In the extreme heat of summer, increase this to 2-3 times per week. During the monsoon season, monitor rainfall and adjust accordingly. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our arid environment.

Signs of underwatering include wilting leaves and dry, cracked soil. Overwatering leads to yellowing leaves and potentially stem rot. A layer of mulch around the base of the plants helps retain moisture and regulate soil temperature, but avoid piling it against the stems.

Regular pruning keeps Geraniums looking their best and encourages continuous blooming. The key is deadheading – removing spent flower clusters as soon as they start to fade. This directs the plant's energy into producing new blooms.

Throughout the growing season, pinch back any leggy stems to promote bushier growth. As our first frost approaches in early December, you can give the plants a final trim to tidy them up before they go dormant.

Geraniums are primarily grown for their beautiful blooms, so "harvesting" is more about maintenance and enjoyment. Expect your first blooms from mid May through early July, about 70 days after transplanting.

Enjoy the flowers in your garden, and regularly remove faded blooms to keep the plants looking neat and encourage more flowering. Simply snip off the spent flower stalks just above a leaf node.

As the first frost approaches in early December, you can bring potted Geraniums indoors to overwinter them, or take cuttings to propagate new plants for the following spring.

Here are some common problems you might encounter with Geraniums in the Desert Southwest:

Botrytis Blight

• What it looks like: Gray mold on leaves, stems, and flowers.
• What causes it: High humidity and poor air circulation, often exacerbated by monsoon moisture.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected foliage immediately. Avoid overhead watering, especially during the monsoon season.

Geranium Budworm

• What it looks like: Holes in buds and flowers, chewed leaves, and visible caterpillars.
• What causes it: Moths lay eggs on the plants, and the larvae (budworms) feed on the buds and flowers.
• How to fix/prevent it: Handpick caterpillars when you see them. Use insecticidal soap or Bacillus thuringiensis (Bt) as a preventative measure, especially during peak moth activity.

Edema

• What it looks like: Small, blister-like bumps on the undersides of leaves.
• What causes it: Inconsistent watering and cool, humid conditions, leading to the plant absorbing more water than it can transpire.
• How to fix/prevent it: Ensure consistent watering and good drainage. Improve air circulation around the plants.

Desert Southwest Specific Challenges: The extreme heat can stress Geraniums, making them more susceptible to pests and diseases. Arid humidity can lead to edema with inconsistent watering. During the monsoon, watch for botrytis blight. Provide afternoon shade during the hottest months, and be diligent about watering and monitoring your plants.

Geraniums make great companions for several plants in the Desert Southwest garden:

• Tomatoes: Geraniums are said to repel tomato hornworms and other pests that can plague tomatoes.
• Peppers: Similar to tomatoes, geraniums can help deter certain pepper pests.
• Corn: Geraniums can attract beneficial insects that prey on corn pests.
• Roses: Geraniums are often planted near roses to help deter Japanese beetles.

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