Geranium in Zone 6A — Northeast

Geraniums are a classic choice for adding vibrant color to our Northeast gardens. Their bright blooms and easy-going nature make them a rewarding addition to containers, borders, and window boxes. Plus, they tolerate the cool nights we often get here, which can actually intensify their colors.

Our short growing season and the occasional late spring frost can be a challenge, but with proper timing and a little planning, you can enjoy a profusion of geranium blooms from mid-summer until frost. With a growing season around 178 days, you'll have plenty of time to enjoy these beauties.

Starting geraniums from seed indoors is possible, but honestly, most of us in the Northeast find it easier to buy established starter plants. Geraniums are very slow to develop from seed, and with our short season, you'd need to start them very early: early to late February, about 12 weeks before you plan to transplant them outdoors.

If you're determined to start from seed, use seed trays with a good quality seed-starting mix. Keep the trays consistently moist by bottom watering – set the tray in a shallow dish of water and let the mix absorb it from the bottom. Provide warmth and plenty of light, especially since our spring weather can be unpredictable.

Transplanting geraniums outdoors can begin from early May through early June, once the danger of frost has passed. Remember, we often get a cool snap even in May, so keep an eye on the forecast!

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Space the plants 10-12 inches apart in a sunny or partially shaded spot. Honestly, buying established starter plants from a local nursery is the easiest way to guarantee a good show of blooms in our short Northeast season.

Geraniums need moderate watering, but it's important to let the soil dry out slightly between waterings. Overwatering can lead to stem rot, a common problem, especially with our sometimes humid summers.

During the active growing season (roughly June through September), check the soil moisture regularly using the "finger test." Stick your finger about two inches deep into the soil. If it feels dry, it's time to water. Aim for about an inch of water per week, either from rainfall or supplemental watering. Water at the base of the plant rather than overhead, especially with our moderate-to-humid conditions, to prevent fungal diseases.

In the spring and fall, when temperatures are cooler and growth slows down, you'll need to water less frequently. Signs of underwatering include wilting leaves and dry, crispy edges. Overwatering can cause yellowing leaves and mushy stems. A layer of mulch around the base of the plants will help retain moisture and keep the soil temperature consistent, which is especially helpful during the temperature swings we sometimes experience.

Deadheading is key to keeping your geraniums blooming throughout the season. Simply pinch or snip off the spent flower clusters as soon as they start to fade.

Throughout the summer, you can also pinch back any leggy stems to encourage bushier, more compact growth. As the first frost approaches in mid- October, don't bother deadheading any further. Let the plant naturally slow down and prepare for the end of the season.

In the Northeast, you can expect your geraniums to start blooming from mid July through late August, about 70 days after transplanting.

Geraniums are grown for their beautiful flowers, so "harvesting" simply means enjoying them in your garden! Regularly remove faded blooms to keep the plants looking neat and to encourage continued flowering. The more you deadhead, the more blooms you’ll get.

As the end of the season approaches and the first frost looms (around mid- October), there's no need to harvest anything. Simply enjoy the last of the blooms before the cold weather arrives.

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

Botrytis Blight

• What it looks like: Grayish-brown fuzzy mold on flowers, leaves, and stems.
• What causes it: High humidity and cool, wet conditions, often exacerbated by our even rainfall and moderate-to-humid summers.
• How to fix/prevent it: Improve air circulation by spacing plants properly. Remove and destroy any infected plant parts immediately. Water at the base of the plant to avoid wetting the foliage. Fungicides may be necessary in severe cases.

Geranium Budworm

• What it looks like: Small holes in buds and flowers, often with dark frass (insect droppings) nearby.
• What causes it: The larvae of moths that lay their eggs on geranium plants.
• How to fix/prevent it: Handpick caterpillars when you see them. Insecticidal soap or Bacillus thuringiensis (Bt) can be effective, especially when applied early in the 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. This is a common problem during periods of heavy rainfall or when plants are overwatered.
• How to fix/prevent it: Improve drainage in the soil. Water less frequently, allowing the soil to dry out slightly between waterings. 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. Be vigilant about watering practices and air circulation to keep your geraniums healthy.

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

• Tomatoes and Peppers: Geraniums are said to repel certain pests that can bother tomatoes and peppers, like aphids.
• Corn: The strong scent of geraniums may help deter corn earworms.
• Roses: Geraniums can help protect roses from Japanese beetles.

Avoid planting geraniums near plants that are susceptible to the same fungal diseases, as this can increase the risk of spreading the disease.