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How to Grow: Geranium
Learn about growing geraniums including how to overwinter them in the North.
Listen to podcast:
Many different types
full to part sun
Bloom Period and Seasonal Color
Spring until fall in colors such as pink, red, white, salmon, and bicolor
Mature Height x Spread
1 to 2 feet x 1 to 2 feet
These are not only my mother’s flowers, but also a joy for everyone. Potted geraniums are one of the classic annual flowers seen in many window boxes throughout New England. There is a perennial flower also called geranium that I cover in that section. They’re most often grown in containers, window boxes or planters close to the house. The large, circular, bright-colored flowers bloom from spring until frost. Given plenty of sun and warmth they’re an easy to grow flower. There are many different types of geraniums. Zonal and Martha Washington geraniums can have bi or tricolored leaves. Ivy-leafed geraniums are a cascading plant with smaller flowers and grow best in hanging baskets. Scented geraniums have small flowers, but deliciously scented leaves.
Where, When and How to Plant
Geraniums can be grown from seed, but are slow to germinate and take up to 4 months of indoor growing before they can be planted outdoors. It’s much easier to purchase favorite varieties from garden centers in spring and then propagate and store them for future years. Plant in full to part sun in a warm area. Don’t rush to plant geraniums outdoors since they love the heat. Wait until you plant other warm season crops, such as tomatoes and corn. Plant them in well-drained containers, such as clay pots that breathe, allowing the water to drain faster. Geraniums don’t grow well in soggy soils.
Pinch the new growth of young geraniums to promote bushier plants, especially if you have overwintered your geraniums and the stems have become tall and leggy. In sunny, hot weather, water well, but otherwise let the soil dry out a bit between waterings. Give plants a monthly dose of an organic plant food.
Regional Advice and Care
Keep geraniums deadheaded to increase flowering and make them tidier looking. Cut back the stems twice during the summer to promote more branching. Bottom water and keep the leaves dry to avoid soil born fungal, leaf spot diseases.
Bring geraniums indoors once outdoor temperatures dip below 40F. To overwinter, cut back the plants by 1/3rd, reduce watering to once a week and place them in a sunny, south-facing window. Another option is to cut them back to 8 to 10 inch tall stems, remove the soil around the roots, and place the roots in perforated, plastic bags filled with slightly moistened peat moss. Place the plants in a dark, cool basement or garage where they won’t freeze. In spring, with signs of new growth, pot up the plants and bring them up to a sunny window to grow.
Companion Planting and Design
Geraniums look great grouped as all one color or in combinations of white, orange pink and red. Grow them in containers with trialing companions such as fan flower or with silver colored flowers such as dusty miller.
‘Apple Blossom Rosebud’ has pink and white flowers while’ ‘Black Velvet Rose’ has chocolate brown leaves with rose-pink colored flowers. ‘Tornado’ is a good ivy geranium series. Scented geranium varieties include flavors such as lemon and rose.
Excerpted from my book, New England Getting Started Garden Guide.
Podcast Transcript: Overwintering Geraniums
One flower that’s often passed along from generation to generation is the geranium. Luckily, it’s also easy to overwinter indoors, since it won’t survive our winters. Here’s how to keep it alive. If you have a sunny, south-facing window, you can simply cut it back to about eight inches tall, leaving just the skeletal structure of stems. For a geranium in the ground, dig it up and pot the plant in a container filled with moistened potting soil.
Keep it in a cool, bright location for a week. Then bring it indoors into a sunny window to grow. It may get leggy in December and January with the low light levels. Simply pinch back the long stems, and eventually, come March with the longer days, it will bush out and flower for you even as the snow flies.
Another way to bring a large geranium indoors if you don’t have room is to take cuttings. Take a four-to-six-inch long cutting from the stem end. Dip the cut end in rooting hormone powder, and stick the cutting in a plastic pot filled with a moistened potting soil. Place the cutting in a bright room, and it will root in a matter of weeks.
For gardeners with no room, another way to store your geranium is to cut back the plant, dig it up, remove the soil and place the root end in a perforated plastic bag filled with slightly moistened peat moss. Check the bag periodically all winter to make sure the roots aren’t rotting or shriveling up. In spring, pot up the plant and let it grow.
From the Connecticut Garden Journal.