Reblogged with permission of the National Garden Bureau:
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In honor of 2012 being the Year of the Geranium, we bring you some quick facts about this much-loved garden plant:
1. The bedding plants gardeners plant in late spring and bring inside in autumn are commonly known as geraniums; but geraniums they are not. They are pelargoniums.
2. True geraniums are the cranesbills, hardy North American and European herbaceous perennials; while pelargoniums are semi-tender or tender plants, mostly from South Africa, that have graced our gardens with their large flowers for decades. (It’s a rather lengthy story about why the difference and to read that, go to the NGB website here.) For this article, we will still refer to the annual bedding plants as geraniums.
3. Traditionally, plants were grown from cuttings (vegetatively propagated). However, in 1962, Dr. Richard Craig of Pennsylvania State University developed a technique for seed scarification (nicking) and bred the first commercially successful open-pollinated, seed propagated geranium, ‘Nittany Lion Red’. Four years later, the first F1 hybrid geranium from seed was developed.
Four Basic Types of Annual Geraniums:
1. Common or Zonal Geraniums (Pelargonium x hortorum) – This is the classic bedding plant, which typically comes to mind when someone says “geranium.” Deriving its name from the “zoned” leaf markings, it thrives both in containers as floriferous single specimens as well as planted out in swaths awash with color in the landscape.
2. Regal and Angel Geraniums (Pelargonium domesticum) – The Regals, which are also known as Martha Washington geraniums, are bushy plants with large blossoms, single or double flowers in dramatic colors and patterns. Regals tend to be spring blooming, requiring cool nighttime temperatures to bud. Angels are smaller versions of Regals developed for their dazzling blooms which look somewhat like pansies.
3. Scented-Leaf Geranium (Pelargonium domesticum) – Scented-leaf geraniums are coveted heirloom plants, still grown today for their pleasing fragrance, unusual foliage, delicate flowers, essential oil and culinary use. The scent, created by oils in the leaves, is released when the leaves are rubbed or bruised. The fragrance of a scented-leaf geranium may remind you of roses, lemons, pineapple, chocolate and other spicy fragrances.
4. Ivy-Leaf Geranium (Pelargonium peltatum) – Plants with long, brittle stems full of sculptured, ivy shaped leaves and gracefully trailing habits are immensely popular for hanging baskets, window-boxes and containers. Flowering abundantly throughout the summer, they have smaller, looser flower umbels of single, semi-double or double blossoms in shades of deep maroon, red or pink.
When shopping for geranium plants, choose plants based on their color and size. Look for healthy leaves, with no discolored spots above or underneath, fairly compact growth with no straggly stems that indicate it was grown in poor light, and no obvious pests.
Geraniums as Bedding Plants
Geraniums are popular garden plants because of their long-lasting flower displays, even under adverse weather conditions. For maximum bloom, plant where they’ll get at least 4 to 6 hours of direct sunlight daily and space them 8 – 12 inches apart. Geraniums need good air circulation, but should be protected from strong winds which can break their brittle branches.
Geraniums should be planted in moisture retentive, but well drained garden soils, at the same level as they were growing in pots. Mulch when possible to reduce soil temperature extremes and weed growth. Promptly deadhead spent flowering stems to promote additional flowering. Pinch stems to prevent legginess and promote bushiness.
Water geraniums regularly if there is no rain, preferably early in the day to allow leaves and flowers to dry before nightfall, which will help prevent disease problems.
Geraniums in Containers
Popular mainstays for containers, hanging baskets and window boxes, geraniums are well-behaved, low-maintenance, high-performaning garden divas.
Use a container with drainage holes to prevent soggy soil, which can cause root rot. Fill the container with a good quality soil-less potting mix (not dirt) and position in full sun.
Water thoroughly, allow to dry out before watering again. Do not use a saucer under the container unless filled with pebbles. Fertilize every 2 weeks with a balanced water-soluble fertilizer at half strength.
Few plants offer such variation in flower color, growth habit, leaf pattern, and scent. Lush growing geraniums are versatile plants perfect for any spot that calls for a splash of sparkling color throughout the season.
The National Garden Bureau recognizes Betty Earl as the author of the full version of this article, which can be found on the NGB website.