Geranium in Zone 5B — Northeast

Geraniums are a classic choice for Northeast gardens, offering vibrant color and a delightful fragrance that can elevate any patio or flower bed. Their versatility allows you to enjoy them in containers, hanging baskets, or directly in the ground, bringing a touch of summer cheer to our often-rocky New England soil.

Our short growing season and the potential for late spring frosts can be a concern, but starting geraniums indoors or purchasing transplants ensures you'll be enjoying their blooms throughout our 168-day growing season. With a little planning, you can make the most of summer with these beauties.

Starting geraniums from seed indoors in the Northeast is possible, but it requires patience, as they are slow growers. If you're up for the challenge, begin in early to late February, about 12 weeks before you plan to transplant them outdoors.

Use seed trays with a good seed-starting mix and provide warmth, either with a heat mat or by placing them in a warm location. Consistent moisture is key, and bottom watering helps prevent damping-off. Since our springs often have late cool snaps, having a head start indoors gives them the best chance to thrive once the weather finally settles.

Transplanting geraniums outdoors in the Northeast should happen between early May and early June, once the risk of frost has passed. 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 them 10-12 inches apart. While you can certainly start geraniums from seed, many Northeast gardeners find it easier to buy starts from a local nursery, especially with our limited growing season. Keep an eye on the weather forecast; those unexpected late frosts can still sneak in!

Geraniums in the Northeast appreciate consistent moisture, but they don't like to be waterlogged. Let the soil dry out slightly between waterings. Overwatering can lead to stem rot, a common issue in our sometimes-humid summers.

During the active growing season, aim to give them about an inch of water per week, either through rainfall or supplemental watering. Use the finger test: stick your finger about two inches into the soil; if it feels dry, it's time to water. Water at the base of the plant to avoid getting the foliage wet, which can encourage fungal diseases in our moderate-to-humid climate.

In the cooler spring and fall months, reduce watering frequency. Signs of underwatering include wilting leaves, while yellowing leaves can indicate overwatering. A layer of mulch can help retain moisture and regulate soil temperature, especially during the warmer parts of summer.

Deadheading is essential for keeping your geraniums blooming throughout the summer in the Northeast. Regularly remove spent flower clusters to encourage the plant to produce more blooms.

Throughout the growing season, you can also pinch back any leggy stems to promote bushier growth. As the first frost approaches in early October, you can bring your geraniums indoors to overwinter them, or simply let them fade with the season.

Geraniums are primarily grown for their beautiful flowers, so harvesting involves enjoying their visual appeal in your garden from mid-July through early September. The 70 days to maturity is just a guideline; the plant will tell you when it's ready to bloom.

Regularly remove faded blooms to maintain a neat appearance and encourage continued flowering. Simply snip off the spent flower heads just above a leaf node. As the first frost approaches in early October, consider taking cuttings to propagate new plants indoors for the following year.

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

Botrytis Blight

• What it looks like: Grayish-brown mold on flowers, leaves, and stems.
• What causes it: High humidity and poor air circulation, which can be common during our moderate-to-humid summers.
• How to fix/prevent it: Improve air circulation by spacing plants properly. Remove and destroy infected plant parts. Use a fungicide if necessary. Water at the base of the plant to avoid wetting the foliage.

Geranium Budworm

• What it looks like: Holes in buds and flowers, with small green caterpillars present.
• What causes it: Moths laying eggs on the plants.
• How to fix/prevent it: Handpick caterpillars. Use Bacillus thuringiensis (Bt) as a biological control. Monitor plants regularly for signs of infestation.

Edema

• What it looks like: Small, blister-like bumps on the undersides of leaves.
• What causes it: Overwatering and cool, humid conditions, which can happen during our cooler spring and fall months.
• How to fix/prevent it: Improve drainage. Avoid overwatering. Provide good air circulation. Ensure plants receive adequate sunlight.

Northeast Specific Challenges: Our moderate heat, moderate-to-humid humidity, and even rainfall can create conditions favorable for fungal diseases like botrytis blight. Monitoring your plants regularly and taking preventative measures will help keep them healthy and blooming throughout the season.

Geraniums make excellent companions for several plants in the Northeast garden. Planting them near tomatoes, peppers, and corn can help deter certain pests, as their scent repels insects like aphids. They also work well with roses, helping to protect them from Japanese beetles.

Avoid planting geraniums near fennel, as it can inhibit their growth. By choosing the right companions, you can create a thriving and pest-resistant garden that makes the most of our short growing season.