Geranium in Zone 5A — Northeast

Geraniums are a classic choice for Northeast gardens, bringing vibrant color all summer long. Their versatility shines whether you plant them in containers, window boxes, or directly in your garden beds. Plus, their fragrance can help deter certain pests – a welcome bonus in our gardens!

Our short growing season here in Zone 5A can be a challenge, but with geraniums, timing is key. By starting seeds indoors or buying established plants, you can easily enjoy these beauties throughout our 153-day growing season, from late spring until the first frosts of early fall.

Starting geraniums from seed indoors in the Northeast *is* possible, but it requires patience. Geraniums are notoriously slow to get going from seed, so many gardeners find it easier to purchase starter plants from a local nursery. However, if you're up for the challenge, starting seeds indoors gives you a wider variety of choices.

Start your seeds indoors from mid-February through early March, about 12 weeks before you intend to transplant them outdoors. Use seed trays with a good seed-starting mix, and provide warmth (a heat mat is helpful) and plenty of light (grow lights are ideal). Bottom watering helps prevent damping off, a common problem with seedlings. Remember, our spring can be late here, so don't rush to put them out too early.

Transplant your geraniums outdoors from mid-May through mid-June, after the danger of frost has passed. Before transplanting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the cooler temperatures and stronger sunlight.

Plant them 10-12 inches apart in well-drained soil. Keep an eye on the weather forecast, as we can still get unexpected frosts even in late May. If a frost is predicted, cover your young plants to protect them. Again, because of the slow start from seed, buying starts from a local garden center is a great way to get a head start on the season.

Geraniums need moderate watering, but overwatering is a common mistake that can lead to stem rot, especially in our humid Northeast summers. Let the soil dry slightly between waterings. The "finger test" is a good way to check – stick your finger about 2 inches deep into the soil, and if it feels dry, it's time to water.

During the warmer months, your geraniums will likely need about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our moderate-to-humid climate. Signs of underwatering include wilting leaves and dry soil, while overwatering can cause yellowing leaves and mushy stems.

A layer of mulch around your geraniums helps retain moisture, suppress weeds, and regulate soil temperature. In our region, organic mulches like shredded bark or compost work well.

Deadheading is essential for keeping your geraniums blooming throughout the season. Remove spent flower clusters as soon as they start to fade. This encourages the plant to produce more flowers instead of putting energy into seed production.

You can also pinch back leggy stems to encourage bushier growth. Simply snip off the tips of the stems just above a leaf node. As the first frost approaches in early October, stop deadheading and let the plants begin to prepare for dormancy.

While you don't "harvest" geraniums in the traditional sense, you can expect them to start blooming profusely from late July through mid-September. The real harvest is the enjoyment of their beautiful flowers in your garden. As the blooms fade, remove them to keep the plants looking tidy and to encourage continued flowering.

To harvest the flowers for arrangements, simply cut the stems at an angle. This encourages new growth and extends the blooming period. As we approach the first frost in early October, you can take cuttings to propagate new plants indoors for next year.

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

Botrytis Blight

• What it looks like: Grayish-brown mold on leaves, stems, and flowers.
• What causes it: High humidity and poor air circulation, especially during periods of prolonged dampness. Our region's moderate-to-humid summers can create ideal conditions for this fungus.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning away crowded foliage. Remove and destroy infected plant parts. Use a fungicide if necessary, following label instructions carefully.

Geranium Budworm

• What it looks like: Small holes in buds and flowers, chewed leaves, and dark droppings.
• What causes it: The larvae of moths that lay their eggs on geranium plants.
• How to fix/prevent it: Inspect plants regularly for signs of infestation. Handpick caterpillars when possible. Use Bacillus thuringiensis (Bt), a biological insecticide, to control the larvae.

Edema

• What it looks like: Small, blister-like swellings on the undersides of leaves.
• What causes it: Excessive moisture in the soil and cool temperatures. This can happen in the Northeast during periods of heavy rain and cool nights.
• How to fix/prevent it: Improve drainage in the soil. Avoid overwatering, especially during cool weather. Ensure good air circulation around the plants.

Northeast Specific Challenges: Our moderate heat, moderate-to-humid humidity, and even rainfall can create favorable conditions for fungal diseases like botrytis blight. Monitor your plants closely and take preventative measures to minimize these problems.

Geraniums make good companions for several plants in the Northeast garden:

• Tomatoes: Geraniums are said to repel tomato hornworms, a common pest in our region.
• Peppers: Similar to tomatoes, geraniums can help deter certain pepper pests.
• Corn: The strong scent of geraniums can confuse corn earworms, reducing damage to your corn crop.
• Roses: Geraniums can help deter Japanese beetles, which can be a nuisance on roses.

Avoid planting geraniums near plants that prefer very dry conditions, as geraniums need moderate moisture.