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Geraniums: Hardy, flowering summer favorites

Geraniums are one of the most loved, reliable and recognized flowering plant that gardeners know. If you think back your mother and grandmother, and probably great-grandmother, grew geraniums. They have been around for more than 300 years. Geraniums were brought over from South Africa to Holland and England in the early 1600s, and have been propagated and hybridized ever since.

Geraniums will grow in almost any type of soil that is well-aerated and porous. Heavy clay soils should be improved by adding organic matter like sphagnum peat moss, partially-rotted manure, or compost to help aerate the soil. One of their most endearing qualities is that they love the hot sun and you can water them once a week and they will survive. However, they do like water and regularly monitored watering will give you a healthier, rich-looking plant. If you use Miracle Gro Bloom Booster (15-30-15), you are going to have more luscious blossoms. I usually recommend that you use the regular Miracle Gro (24-8-16 half strength each week) for your blooming flowers and start with a bloom booster about July 1 to give them a little extra push. However, with geraniums you may want to push them all season, just because they are such a hard-working plant and they will respond to the treatment.

Geraniums should be set out in the spring after danger of frost is past. Geraniums that have been injured by cold temperatures will produce little growth and the foliage will often be red. It will also take a long time for them to recover from cold temperatures. They do not like temperatures in the 30s and 40s. They like the hot sun and if it is a cool summer, they will not do as well as if there is a lot of heat.

Geraniums plants are generally available as rooted cuttings or as seedlings at gardening centers in the spring. Plants should be set in the soil no deeper than the depth they were growing in the pot. If possible, plant more shallow. Stem rot will kill geraniums that are planted too deeply. Once planted, firm the soil around the roots. Be careful not to injure the stem of the plant, as this provides an opening for disease to enter. Water thoroughly after planting.

Pest problems are minimal with geraniums. Always keep fading flowers stalks removed to reduce botrytis, which is a problem during the wet season. Proper plant spacing will help minimize botrytis. Bacterial blight can be a serious problem on geraniums--usually in evidence when the plant or single leaves wilt for no apparent reason. No spray is available and the plant should be removed from the site immediately.

There are many types of geraniums from which to choose.

The common or zonal geranium is probably the one we most often find as a bedding plant. These are compact plants, some having very decorative, distinctly marked two-and three-colored leaves. They come in colors of reds, pinks and white. Many hybrids have bi-colored flowers and are salmon colored.

Ivy-leaved geraniums are perfect for hanging baskets and window boxes. Although flower petals are narrower and the blossoms less dense than other cultivars, the ivy leaved geranium is an attractive vining plant that can grow up to three feet long. They like moist soil and and cooler temperatures, and do best in a north or east exposure. Ivy types do not tolerate temperatures above 85 degrees for long periods.

Martha Washington or Regal geraniums are sold in early spring and always looks so lovely because they like cool temperatures. They require 60 degree temperatures or below in the night to stay in bloom. Warm summer temperatures will cause flowering to cease until fall when temperatures again become favorable.

Scented geranium are used for making tea, potpourris and sachets. They need to be grown in full sun to develop the volitile leaf oils. Flowers are less significant with this group, but the soft-scented leaves carry fragrant oils which can be used for the above or will add fragrance to a patio, porch or kitchen.

The mosquito geranium is also a scented geranium which is a hybrid especially for the production of oil of citronella and frequently is sold at nurseries as the mosquito plant.

This fall I will write about taking cuttings for propagation and over wintering geraniums.

Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.