Geraniums are sun-loving plants. They will grow in window boxes and pots on the east, south, or west side of
the house and on terraces with sun for half a day. In spite of their love of sunshine, they will even flourish with just a little, provided they receive plenty of strong light. The north side of a house, beyond the shade of trees, will produce extraordinary plants. When geraniums are grown against hot, sunny brick, concrete, or stone walls or pavements, some shielding from the torrid noonday sun is advisable. This is to cut down on reflected heat through the middle part of the day.
Soil and Potting
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. A combination of three parts good garden loam and one part leafmold, peatmoss, or compost plus a five-inch pot of bonemeal to each bushel is good. If the garden loam is heavy, add sand. Acid soil will also need some lime. I have success with good garden soil and a sprinkling of a 5-10-5 fertilizer and bonemeal. During the growing season, plants respond to a low-nitrogen fertilizer in liquid form.
When potting, be generous with drainage material to insure free passage of water. 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. Both extremes cause legginess, a common complaint from gardeners.
Keep up Appearance
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 and 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. This is admittedly an exacting chore for the busy gardener, but one that greatly improves the appearance of plants.
On the whole, geraniums are pest free, but if insects prove troublesome, malathion or lindane will clean them up. To your delight, you may even discover dead Japanese beetles on the foliage, since flower and leaf parts contain a substance that is poisonous to this pest.
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