All over the country, seasonal bedding geraniums flaunt their red and scarlet, rose, pink, and white blooms with a gay abandon that few other plants can rival. In boxes on city fire escapes and rooftops, in window boxes on suburban and country houses, in tubs and pots on terraces and patios, and in hanging baskets of the porches of summer cottages, they are beloved and cherished plants.
What we would commonly call geraniums are really Pelargoniums. They are part of the bigger family of geraniums, of which there is a large genus of hardy plants, known botanically as Geranium and commonly, as cranesbills. In the UK, our summer bedding geraniums are not fully hardy and need to be brought inside over winter in most parts of the country.
The geranium needs sun to bloom; it tolerates shade, where it is usually handled as a foliage plant. What it resents is too much moisture and a rich diet. Kept too wet, the leaves turn yellow; given a heavy soil, one high in nitrogen plants go to foliage and flower sparingly.
Even if you choose no other plants, you could have a varied potted garden of single and double zonal, fancy-leaved or variegated, scented-leaved, ivy and Lady or Martha Washington geraniums (also called show or fancy geraniums).
The zonal geranium is characterized by dark circular markings on the rounded green leaves. Double types dominate the trade and are offered by florists in the spring for planting in gardens and window boxes.
Variegated geraniums, with leaves that are often brilliantly colored, are attractive even out of bloom. Set among green-leaved geraniums and other foliage plants, pots of the variegated plants add color and pattern.
The trailing, ivy-leaved geraniums are among the most profuse flowering when grown under favorable conditions. They dislike shade and high humidity and thrive best in climates with warm days and cool nights
Geraniums flourish and look well in pots, boxes, and planters. They thrive in various soil mixtures if drainage is good. For abundant bloom, however, supply a special preparation, not high in nitrogen, or lush foliage and few blooms will result. I have success with good garden soil and a sprinkling of a 5-10-5 fertilizer and bone meal. During the growing season, plants respond to a low-nitrogen fertilizer in liquid form.
When potting, be generous with drainage material to ensure free passage of water. As with any plant, always water with care, since too much or not enough can be harmful. The best rule is to water when the surface of the soil feels dry. Then soak the soil well and do not water again until plants need it. If soil is kept too wet, leaves will turn yellow; if too dry they wilt and discolor.
To maintain even plant growth, turn containers from time to time. Remove yellow leaves and faded blossoms which are especially distracting on plants at doorways or any other key spots. If rain rots and disfigures the center florets of the heads, pull them off with your fingers, leaving the unmarred outer florets and buds.
If you want plants for next spring, take two- to four-inch cuttings in August or early September. Look for mature stems (with leaves spaced close together) that break easily like a snap bean. Woody growth is hard to root and succulent tips tend to rot. Before planting spread out cuttings in a shady place for several hours so leaves will lose excess moisture.
When ready to plant, cut off the lower leaves, allowing but two or three to each cutting. Also pull off the little wings on the stem, since they are inclined to rot. Dip stem ends in hydrated lime to prevent decay and then insert about halfway, in a flat or large pot of pure sand or a mixture of sand and peat moss. With geraniums, rooting powders are hardly necessary. When cuttings develop inch-long roots, they are ready for spacing out in another flat or for separate planting in 2 inch pots. Fill with a mixture of three parts sandy loam and one part peat moss or leaf mold. After planting, keep in the shade for the first few days, and bring indoors before cold weather.
When the separated cuttings have developed strong root systems, shift to 3 or 4-inch pots. Use the same potting mixture as before, with bone meal added. Later as established plants begin to grow, feed periodically with a high phosphorous fertilizer, as 5-10-5 or 4-12-8.
To keep plants bushy and to encourage branching, pinch while small, starting when they are three to four inches high. Provide sunny windows, and keep turning pots to prevent lopsided growth. Water regularly, but allow soil to dry out just a little between applications.
Plants may be wintered in cool cellars with little light. Remember only that the less light, the cooler the temperatures should be. This is because too much warmth and insufficient light cause lanky growth that undermines a healthy plant.
Gardeners with cellars or sheds when temperatures remain above freezing, can winter geraniums hanging upside down from the ceiling. The dead-looking sticks, set out in pots or in the garden in warm weather, will astound you when they develop into glorious flowering plants.