We know them as simply "geraniums". They are one of the most popular container plants, yet they are not really geraniums at all. Botanically they are Pelargonium. How's that for a mouthful? There are true geraniums, the perennial cranesbills, but they look little like the annul plants we commonly call geraniums. The confusion with the names can be traced back to disagreements between botanists over classification and is of little importance to most gardeners, except for the distinction that perennial cranesbill geraniums will come back each year and zonal geraniums, those now classified as Pelargonium, are topical perennials usually grown as annuals. They got the prefix "zonal" because of the markings on their leaves.
Zonal geraniums were discovered in South Africa and if you have a similar, tropical climate, you can grow them as perennials. Along with zonal geraniums, there are 3 more commonly grown types of Pelargonium:
01 Ivy-Leaf Geranium (Pelargonium peltatum) – As their name implies, these geraniums have a trailing habit and ivy-shaped leaves. The flowers are smaller and less showy than zonal geraniums and the plants are often used as spillers in containers.
02 Scented-Leaf Geranium (Pelargonium domesticum) – Scented geraniums get their fragrance from the oil in their leaves. They can mimic all kinds of scents, like lemon, rose, mint, pine, fruits and even chocolate. The flowers tend to be small and often insignificant and the leaf shapes will vary. Besides their ornamental and fragrant appeal, many can also be used in cooking.
03 Regal and Angel Geraniums (Pelargonium domesticum) – The Regals, also referred to as Martha Washington geraniums, are full, bushy plants with flowers in unusual colors and
Zonal geraniums are bushy plants, mainly used for containers and bedding. There has been considerable breeding done, particularly for size and abundance and colors of flowers, so there is a good deal of variety.
■ Leaves: Oval leaves grow on succulent stems. The leaves often have zones of maroon or bronzy-green. Flowers: Flowers can be single (5 petals) or double and come in clear white, pink, salmon, orange, red, magenta, lavender and bi-colors.
Sun Exposure: Full sun to Partial Shade. They will bloom best in full sun.
Zonal geraniums start blooming in mid-spring and will repeat bloom until frost. Deadheading the entire flower stalk after the flower fades will encourage more blooms.
Zonal geraniums have gotten a bad reputation by plant snobs. They've been considered garish and common. Too many of the brightly colored plants can start to look over the top, but these plants are excellent in all kinds of containers. The brighter reds are very elegant all alone and pair well with flowers in equally bright colors, like portulaca or nasturtium. The softer pinks and salmons complement blue and purple flowers and the lavender shades really stand out next to the chartreuse foliage of Huechera or sweet potato vines.
Soil: Zonal geraniums are not terribly fussy about soil pH, but prefer a slightly acid soil of about 5.8 to 6.5
Planting: You can start zonal geraniums from seed, cuttings or transplants. Taking cuttings was the traditional method of propagating geraniums and maintaining favorite varieties. If you choose to take cuttings, make sure you only use healthy, vigorous plants.
Zonal geraniums are not heavy feeders, but since they are usually grown in containers, a light feeding with your favorite fertilizer, every 2-4 weeks, will keep them vigorous.
Stressing them slightly by watering only after the soil has dried out completely for a day or two seems to encouraging more profuse blooming. Just don't leave them dry for so long they start dropping leaves and declining. Interesting tipbit....
There are a few fungal and bacterial diseases to look out for, mainly
■ Stem or root rot caused by poorly drained soil.
■ Gray mold or botrytis, especially in humid or damp weather, which causes grayish fuzz on the leaves and eventually a slimy mush.
taken from https://www.thespruce.com/growing-and-caring-for-annual-geranium-plants-
till next time, this is Becky Litterer, Becky's Greenhouse, Dougherty, Iowa