The Q&A Archives: Geraniums

Question: What is the difference between seed geraniums and zonal geraniums? Does one have better blooming habits that the other? What is the best method of propagation?

Answer: Zonal Cutting Geraniums - This is the term for the standard version of geraniums that are propagated vegetatively, by cuttings. Typically, they have large (4-6 inch) rounded flower heads held well away from the plant. The leaves are also large, often 3-4 inches across. The plant habit tends to be rather upright and branching, generally growing from 12-24 inches tall. Some of the old, standard varieties of zonal geraniums are 'Crimson Fire', 'Penny Irene', 'Ritz', 'Schoene Helena' and 'Aurora'. Plant breeders have improved on the old standards developing series such as Americana (in various colors) that are more compact and stronger.

Zonal Seed Geraniums - As the name implies, seed geraniums are grown from seed. They produce a more compact, affordable version of the old-fashioned zonal geraniums and although their flowers are smaller, the plants are more floriferous. Their flower heads are generally 3-4 inches across and more open than the cutting zonals. These plants form a low, compact mound typically about a foot tall and wide. Seed geraniums are most often used in large landscape plantings and in smaller containers such as window boxes. Some of the most popular series of seeds geraniums are Multibloom, Elite, Pinto and Orbit. Each series will come in several colors such as Multibloom Scarlet, Pinto Rose or Cherry Orbit.

Propagation ? Most geraniums root easily from stem cuttings, and many cultivars must be vegetatively propagated to maintain desired flower and/or leaf color, shape and scent. Propagate in the fall, allowing for 3 to 4 weeks of frost-free weather for rooting to take place. Take cuttings from September (mountains) to October (Coastal Plain) from healthy mother plants which have been kept rather dry for several weeks. Take cuttings 3 to 4 inches in length from the growing tips of branches. Trim off the leaves from the base of the cutting, stick them into a coarse, sandy medium in small pots or flats, and water well. Provide indirect light and do not allow the cuttings to dry out. After roots are formed, place cuttings in full sun and water only enough to keep the cuttings from shriveling. Keep the surface soil dry to reduce diseases. Fertilize with a water-soluble fertilizer every two weeks.

Many bedding geraniums are seed-grown. Geranium seeds have a very hard seed coat which can inhibit germination, so home gardeners often scarify seeds (scratch to break the seed coat) to allow water to enter. Sow seeds in winter approximately 3 months before the last frost date. Sow in a flat in commercial seed starting medium, spacing seeds 1/4 inch apart in a row, with 1 to 2 inches between rows, covering lightly and maintaining the flats at 72?F. Keep the medium moist but not overly wet by misting. A plastic "greenhouse top" or plastic wrap draped over the flat will ensure high humidity, but don?t forget to vent the flats if placed in direct sunlight. Germination usually occurs in 7 to 14 days, but may be delayed and irregular. After germination, reduce the humidity, keep seedlings well ventilated and somewhat dry, but never allow the seedlings to dry out completely. The young seedlings must be carefully pricked out and transplanted into larger containers, such as 4 inch pots. Grow the young geraniums with 72?F days and 65?F nights. Supply supplemental light from fluorescent tubes to give 14 to 18 hours of light per day. Fertilize every 2 weeks with a water soluble plant food from the time of germination until planting outdoors. Most geraniums will flower in 95 to 110 days from germination.

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