Geranium in Zone 7B — Desert Southwest

Geraniums are a fantastic addition to any Desert Southwest garden, offering vibrant blooms and a delightful fragrance that can enhance your outdoor spaces. Their versatility extends beyond aesthetics; the leaves can be used to infuse teas or add a unique flavor to desserts. Successfully growing geraniums here is incredibly rewarding.

While the extreme heat and intense sun of our Desert Southwest climate can pose challenges, careful timing and attention to watering will ensure your geraniums not only survive but thrive. Our long, 245-day growing season gives you two opportunities for planting and enjoying these beautiful flowers.

Starting geraniums from seed indoors is possible, but it's honestly a bit slow. If you're feeling ambitious and want a specific variety, go for it. Start seeds indoors from late December through mid January, about 12 weeks before you plan to transplant them outdoors.

Use seed trays with a good seed-starting mix, providing warmth (a heat mat helps) and plenty of light – a grow light is essential. Keep the soil consistently moist by bottom watering to avoid disturbing the tiny seedlings. Remember, our very-early spring means you need to get a head start indoors if you want blooms early in the season.

Transplant your geranium seedlings outdoors from late March through late April, after the danger of frost has passed. Before transplanting, harden off the seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense Desert Southwest sun and temperature swings.

Plant them 10-12 inches apart in well-draining soil. Honestly, buying starts from a local nursery is the easiest way to go. They're already acclimated to our climate, and you'll get blooms much sooner.

Watering is absolutely critical for geraniums in our Desert Southwest climate. While they need moderate moisture, overwatering is a common killer, leading to stem rot. Let the soil dry out slightly between waterings.

During the cooler spring and fall, water deeply once or twice a week, providing about 1 inch of water each time. Use the "finger test": stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water. In the extreme heat of summer, you'll likely need to water every other day, or even daily during the hottest stretches. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our arid climate, especially when monsoon moisture arrives.

Signs of underwatering include wilting leaves and dry, crispy edges. Overwatering shows as yellowing leaves and a mushy stem base. A layer of mulch around the base of the plants helps retain moisture and regulate soil temperature, but avoid piling it against the stems.

Deadheading is key to keeping your geraniums blooming throughout the season. Regularly remove spent flower clusters by snipping them off just above a leaf node. This encourages the plant to put its energy into producing new flowers instead of seeds.

You can also pinch back any leggy stems to encourage bushier growth. Simply trim the stems back a few inches. As the first frost approaches around mid- November, stop deadheading to allow the plant to harden off naturally.

Your first geranium blooms should appear from early June through late July, about 70 days after transplanting. Geraniums are grown for their flowers and foliage, so "harvesting" really means enjoying their beauty in your garden. Remove faded blooms to maintain a neat appearance and encourage continuous flowering.

There's no need to wait for a specific sign of ripeness; just snip off the spent flowers as they fade. To harvest, use clean scissors or pruners to cut the flower stem close to the main stem. As the end of the season nears and the first frost looms around mid- November, you can bring potted geraniums indoors to overwinter them, or simply let them go as annuals.

Here are three common problems you might encounter with geraniums in the Desert Southwest:

Botrytis Blight

• What it looks like: Grayish-brown mold on flowers, leaves, and stems.
• What causes it: High humidity and poor air circulation, especially during our monsoon season.
• How to fix/prevent it: Provide good air circulation by spacing plants properly. Water at the base of the plant to avoid wetting the foliage. Remove and destroy any infected plant parts immediately.

Geranium Budworm

• What it looks like: Small holes in flower buds and leaves, often accompanied by dark droppings.
• What causes it: Caterpillars feeding on the plant.
• How to fix/prevent it: Inspect plants regularly for caterpillars. Handpick them off or use Bacillus thuringiensis (Bt), a biological insecticide, to control them.

Edema

• What it looks like: Small, water-soaked blisters on the undersides of leaves.
• What causes it: Overwatering or poorly draining soil, leading to the plant taking up too much water.
• How to fix/prevent it: Ensure well-draining soil. Water less frequently and allow the soil to dry out slightly between waterings.

Desert Southwest Specific Challenges: The extreme heat can stress geraniums, making them more susceptible to pests and diseases. The arid humidity means you need to be diligent about watering correctly to avoid both underwatering and overwatering. During monsoon season, watch out for fungal diseases and provide good air circulation.

Geraniums make good companions for several plants in the Desert Southwest garden. They can help deter pests from tomatoes, peppers, and corn. The strong scent of geraniums is also said to repel aphids from roses, making them a valuable addition to your rose garden.

Avoid planting geraniums near fennel, as fennel can inhibit their growth. Otherwise, they are generally compatible with most other garden plants.