July 2007

Enhancing the Value of Your Home

By
The National Garden Bureau

Photo courtesy
Images by BA

Should we call them geraniums or pelargoniums? By any name, they are definitely as sweet. The familiar geranium that gardeners buy in abundance at garden centers each spring, or raise from seed in their homes, is Pelargonium. It's a tender perennial in the same family as the hardy perennial Geranium, and it's one of the most useful and varied plants you can cultivate, whether your garden is a large border or a collection of containers on a deck.
 
A STEP BACK IN TIME
The first plants--Pelargonium triste--were brought from South Africa to England by famed plantsman John Tradescant in the early 17th century. The National Garden Bureau found that Paul Hermann, a Dutch botanist, brought back fragrant Pelargonium cucullatum, which is an ancestor of the regal geranium. Other explorers collected P. peltatum--the ivy geranium--P. inquinans, and P. zonale; the latter two played a major role in the formation of the modern geranium, P. xhortorum. African pelargoniums quickly became popular conservatory plants, although rare enough that only the well-to-do could afford them. And when you have something new, you'll find amateur enthusiasts and serious scientists looking for something even newer and better. By the beginning of the 18th century, both groups were hybridizing species and propagating the new plants from cuttings. As early as 1732, references were being made to P. xhortorum, the garden geranium.

In 1760, seed of pelargoniums were sent to John Bertram of Philadelphia, marking the arrival in America, and plants were brought back from France by Thomas Jefferson in the '70s and '80s.

Mistakenly called geraniums, it wasn't until the end of the 18th century that pelargoniums were placed in their own genus. For decades they were listed as species of Geranium, the European perennial. Separation finally was based on the shape of the floret, which is really an umbel made up of a cluster of florets, and the seed capsule--both of which are quite different from that of Geranium. But the common name has remained, at least in North America. Many gardeners consider a geranium to be an annual because the plants die at the end of the growing season.

Names notwithstanding, the difficulty in hybridizing geraniums was in getting plants to produce seeds and then getting the seed to germinate. Many of the best-known hybrids of the last century were actually sports (natural mutations) of existing Pelargonium xhortorum; the sports were propagated from cuttings of the sported stem--a slow process for increasing the number of plants. Those that were produced from seed were open pollinated, but the geraniums didn't breed true from seed. Gardeners couldn't sow seeds of a specific variety and grow plants with the same traits. If a seed-produced hybrid was deemed beautiful or different enough to perpetuate, it had to be done with cuttings of that original hybrid.
 
UP TO THE PRESENT
In the late 1950s, Richard Craig and Darrell Walker, of Pennsylvania State University, began to work on growing varieties of P. xhortorum from seed in order to produce disease-free geraniums. Working under Walker's supervision, Craig discovered how to improve the germination rate of geraniums. It used to take up to six months for geranium seeds to germinate, with maybe a 40 percent success rate. Craig narrowed that span to two weeks with 80 to 90 percent germination. The problem all along had been the seed coat, which was impermeable to water and oxygen; simply scarifying (nicking) the seed coat allowed water and oxygen to enter the seed for germination. And if you could grow reliably from seed, you could breed for specific traits, such as flower color, compact growth, disease resistance.

As a result of developing the technique for seed scarification, in 1962 Craig bred the first commercially successful seed-propagated geranium: 'Nittany Lion Red'. Named for the university mascot, 'Nittany Lion Red' was an open-pollinated, bright red geranium with single-flowers. This variety was introduced by Ferry-Morse Seed Company in 1965.

In 1966, Dr. Lowell Ewart of the Joseph Harris Seed Company, Rochester, New York, developed the first F1 hybrid geraniums from seed. The first geraniums were named the 'Moreton' series after the Moreton Farm, the location of the seed company. These first hybrids were Moreton White, Deep Salmon, Scarlet Picotee, Red and Scarlet (later renamed 'New Era'). In 1968, three colors in the 'Carefree' series of F1 hybrids from PanAmerican Seed Company won All-America Selections awards: 'Carefree Bright Pink, Deep Salmon, and Scarlet.'

The hybrid seed-geranium market was still in its infancy in the seventies and eighties. Two companies decided to work together on a breeding program. In 1973, two companies--Goldsmith Seeds in the U.S. and Sluis & Groot in the Netherlands--collaborated to introduce the early blooming 'Sprinter' series. Both companies thought there might not be a large enough market for seed-grown geraniums to conduct research individually. In 1977, a later introduction from that series, 'Showgirl', became an AAS winner. Novartis Seeds, formerly Sluis & Groot, introduced 'Ringo' geranium, the first seed-grown geranium to have a really pronounced dark zonal pattern on its leaves. 'Ringo' was introduced in 1978.

All of these hybrids were produced from diploid geraniums. Diploids have two sets of identical chromosomes. Tetraploids have twice the number of chromosomes and produce thicker stems, leaves and usually semidouble florets. The first tetraploid geranium, a spontaneous mutation, was discovered in France in 1870 by Paul Bruant. Not until 1991 was a tetraploid hybrid geranium developed that would come true from seed: the All-America Selections winner 'Freckles', bred by PanAmerican Seed Company. 'Freckles' has pink florets with a rose spot on each petal.

With its varied history and many species, the geranium has a wide-open future. From dwarf to compact to tall plants; single, semi-double, and double florets; increased disease resistance; early bloom--and even fragrance--the possibilities are incredible.
 
GERANIUMS FROM SEEDS OR CUTTINGS?
There are more than 200 species of geraniums, only a few of which are widely grown. The annual geraniums we grow most often in our gardens and homes are divided into four basic types: zonal, or common (Pelargonium xhortorum); ivy-leaved (P. peltatum); regal, or Martha Washington (P. xdomesticum); and scented-leaf (P. graveolens, tomentosum and others). Within those types, some can be propagated from seed, some only vegetatively from cuttings.

Seed or Cutting? What do you look at first when you purchase a geranium? Color, probably. The look of the flower itself--whether the florets are single, semi-double, or double--may influence you when you consider how you're going to use it--massed in a garden bed or spilling from a hanging container, for instance. Geranium flowers are composed of a cluster of florets, and each floret is either single, semi-double, or double (only one type to a plant), one color or bicolor.

Chances are you may not be aware if the geranium you're buying was grown from seed or a cutting. There are advantages and disadvantages to both.

Seed-grown. Geraniums from seed are primarily available in single-flowered form only. Their flowers tend to shatter--a drawback for growers but an advantage for you because you don't need to groom the plants, pinching off dead blooms. The colors can be spectacular and include a wide range: bright red, scarlet, scarlet-and-white, orange-salmon, coral, pink-and-white, soft pink, hot pink, pure white, and lavender. Zonal and ivy geraniums are the types you can grow successfully from seed.

Cutting-grown. Geraniums grown from cuttings--vegetatively propagated--can have single, semi-double or fully double florets. You can tell if the geranium you bought was cutting-grown by noting the type of floret it has (semi-double or double) and by observing whether or not the flower umbel shatters. If the umbel does not have a tendency to shatter it probably is a cutting geranium. Gardeners usually remove the dead umbel from the plant for cosmetic reasons but it also helps reduce the risk of fungal diseases. In addition to zonal and ivy types, regals (Martha Washingtons) and scented-leaf types are cutting-grown geraniums.
 
STARTING GERANIUMS FROM SEED
Geranium seeds are a fairly good size so they're not difficult to sow. Sow the seeds indoors six to eight weeks before the average last frost date in your area; if you live in a frost-free area, simply count back from the date when you'd be setting other warm-weather annuals in the garden.

Sowing
Fill individual peat pots or a shallow container, or flat, with a commercial seed-starting mix to within a half-inch of the rim. If you're using a homemade container, such as a milk carton, poke a few holes in the bottom for drainage so the mix doesn't get waterlogged. Moisten the mix thoroughly and let it drain.

Sow one or two seeds in each pot. Make shallow "rows" in a flat by dragging a pencil through the mix and evenly distribute the seeds about a half-inch apart. You don't have to sow thickly. Cover the seeds with 1/8 inch of the mix and pat it down lightly. Then use a spray bottle to mist the top of the mix to make sure it's moist.

Put a label in each pot and place the pot or flat in a plastic bag and tie it closed with a twist tie to keep the mix from drying out while the seeds are germinating. Check it occasionally and if the mix seems dry, water it from the bottom (so you don't dislodge the seeds) by setting it in a shallow pan and letting the water slowly soak up from below.

Set the pots in a warm location; the seeds don't need light to germinate. Try to keep the growing medium between 70 and 75 degrees F (21 to 24 degrees C)--you can use a heating coil or place the pots on top of a refrigerator, for instance. The seeds should germinate in one to two weeks. Check the seeds daily, when you see green, remove the tie, open the plastic bag for air. Gradually remove the plastic bag from the seedlings. Continue to keep the mix evenly moist--not soggy--by watering the pots from the bottom.
 
Caring for Seedlings
When the seedlings have two true leaves (the first leaves are not), transplant them into individual 2-1/4-inch containers.

Seedlings in individual peat pots can remain where they are, but they should be thinned so that only the strongest-looking one remains; snip out the other with a scissors.

Grow the seedlings in a south window that provides direct, unobstructed sunlight, or place them in a fluorescent light garden with the lights on for 12 to 14 hours daily.

Feed weekly with a water-soluble fertilizer diluted to half-strength.

Let the soil dry slightly between watering.

If the plants start to stretch (the stems elongate between the leaves), you may want to pinch off the top to encourage branching and keep the plants growing compactly.
 
PUTTING GERANIUMS IN THE GARDEN
Geraniums are warm-weather plants, although they won't be killed by a light frost.

Preparing seedlings for the outdoors. To get plants used to the outdoors with its drying sun and wind, harden them off before setting them in the garden. Put the pots or flats outside in a protected spot for a few hours every day for a week or so; hold off on feeding them during this period. Each day, increase the time spent outdoors. Bring them inside at night and if cool weather is forecast.
Selecting a site. Geraniums need full sun to grow and flower well. That means a location that receives six or more hours of direct sun daily. In areas with excessive heat (over 90 degrees F) it is recommended to grow geraniums in a semi-shade location. Beyond that requirement, geraniums look great in a variety of gardens: Use them on their own in beds, edging a perennial border, mixed in with other annuals, in patio containers and window boxes--really anywhere you want a vibrant touch of color that will last all season.

Getting the soil ready. Geraniums grow well in a fairly rich soil that has good drainage. When you have selected a site, dig the soil to loosen it and work in a 1- to 2-inch (2.5 to 5 cm) layer of compost. Add about 1 pound of 10-10-10 fertilizer per 100 square feet. Then rake the soil smooth.

Purchasing flowering plants. If you're not going to grow your own geraniums from seed, you'll find many choices in growth habit and flower colors at garden centers. When you buy, look for healthy, dark green leaves with no discolored spots above or underneath; fairly compact growth--no straggly stems that indicate the geraniums were grown in poor light; and no obvious pests on stems, leaves or buds. It's helpful if the plant is labeled with its cultivar name.

Ivy geraniums are most often preplanted in hanging containers. Look them over the same way you would regular geraniums. You shouldn't need to repot them when you get them home. If you don't intend to plant the geraniums the day you bring them home, water them well and set them in a shaded spot outdoors.

Transplanting into the garden. The best time to transplant is on a cloudy day or in late afternoon so that the plants have a chance to get settled in before they have to contend with the drying effects of the sun. Set geraniums in the ground at the same depth or slightly below the level they were growing in the pots. If you're transplanting from flats, try to keep as much soil around the roots as possible, so they don't dry out. If you grew in peat pots, gently tear off the bottom of the peat pot to encourage roots to grow into the soil. Set the pots below the soil line because they have a tendency to dry out quickly if exposed to the air. Space the plants about 8 to 12 inches apart, far enough apart so that each plant will have good air circulation around it but close enough so that the planting as a whole will make an impressive showing.
 
CARING FOR GERANIUMS
Although geraniums are relatively care-free, they do need some attention.

They're heavy feeders, so you should fertilize them every two weeks or at least once a month. Use a balanced, water-soluble fertilizer (look for 10-10-10 or 20-20-20 on the label). Or feed them once for the season when you plant them by using a time-release fertilizer; follow label directions for amounts.

Feed container-grown geraniums once a month with fertilizer diluted to half-strength (or follow label directions for containers).
Towards the end of the growing season, the cooler nights and still-warm days of fall perk geraniums up; they often produce even more blooms than they did during the summer. Give them an extra boost of fertilizer to extend their beauty.

Water regularly, if it doesn't rain. Check the soil in containers daily during hot summer weather and water if it's dry to a depth of 2 inches or more. Watch for signs of disease and, if you spot any, remove the affected part.
 
GERANIUMS IN CONTAINERS
One of the many nice characteristics about geraniums is that they grow so well--and look so good--in containers on decks, patios, and porches and along walks, so if you don't have a garden site in full sun, you can still enjoy the plants. You'll just have to move them around occasionally to get the benefit of whatever sun you do have. They won't grow and flower well in shade. All geraniums grow well in pots. They combine well with a number of other plants: lobelia, vinca vine, parsley, petunias, verbena, dusty miller, and ageratum, to name a few.

If you want to plant in window boxes, select windows that face south and are unobstructed by trees. And watch the overhanging eaves, which can produce some shade and may also prevent the plants from getting enough water from rain.

Ivy geraniums are naturals for hanging containers, and they will grow well with less sun than common geraniums--handy, since they are usually hung from an eave, tree branch, or pergola where less sun penetrates. But don't think of them as shade plants, the way you might impatiens. Ivies have a tendency to become somewhat bare in the center as the season progresses, so you may want to plant them with other annuals.

Geraniums can be trained into standards, or tree forms, and these are excellent for pots.

To plant in containers. Select a container that has drainage holes in the bottom or sides. Use a soilless mix because it's light in weight. Containers filled with soil and plants can be heavy; you're probably not going to be moving a window box around, but you may very likely change the positions of containers on a deck or patio. Soilless mixes are widely available at garden centers. Don't use soil from the garden; it may not have good drainage and may contain diseases or weed seeds.

Arrange the plants on top of the mix before unpotting them, until you have a design you like. Then unpot and set them in the mix at the same level they were growing originally. Do not use a saucer under the container. Allow water to fully drain from the pot.
 
GERANIUM PROBLEMS
Relatively pest free, geraniums can fall prey to a few diseases in the home garden. Of all of those below, the most likely to be a problem in the home garden is botrytis.

Botrytis is an airborne fungus that tends to show up when days are warm but nights are cool enough to create a "drippy" dew in the morning or when days are overcast and rainy. You'll notice it first on the blooms, which will look moldy; eventually they will get brown and mushy. It's a very fast-acting fungus, spreading rapidly from one petal to the next, one plant to the next. The best treatment is removal of the affected blooms and, if necessary, the whole plant. Don't compost the plants; wrap them up and dispose of them in the trash.

Xanthomonas is a bacterial disease (Xanthomonas campestris pv. pelargonii) that has to be brought into the garden. If you--or a neighbor--bring home an infected plant, the bacteria can get into the soil and pass the infection on to other geraniums; if you brush up against an infected plant, you can pass it on to others. Xanthomonas (pronounced ZAN-the-moan-us) attacks the vascular system, plugging it up so that the plant--or part of it--wilts, especially in the heat of the sun. One of its early symptoms is leaf spot; eventually the lower leaves yellow, then brown, but they don't drop off. The plant wilts and dies. Xanthomonas is quite host-specific and lives in the soil for only about three months, but if you hold over a plant that has it, you can perpetuate it. The only treatment is disposal--either burn it or put it in a trash bag.

Two problems are geographic: Geranium rust in the Carolinas, Virginia, and warmer zones; geranium bud worm primarily west of the Mississippi River.

Geranium rust is airborne and affects only geraniums (Pelargonium). It doesn't overwinter in colder zones. Symptoms include dusty, orange rings on the bottoms of leaves. The plant defoliates. Treatment involves removing affected leaves immediately; the best solution, however, is to take out the plant and dispose of it in a bag--doing so with as little air movement as possible.

Geranium bud worm invades the flower bud and blasts it--the bud is destroyed from within by a tiny caterpillar. The best treatment is to handpick the eggs and the worms off the plants--if you spot the pests before they bore their way into the buds.

Chances are, you may never encounter any of these pests. Geraniums are one of the easiest, prettiest, and most adaptable flowering plants you can set in your garden. Whether your color preference runs to bright reds and oranges or to subdued pinks, lavender, and white or delightful bicolors, you'll find a geranium to match.

The South Carolina Nursery and Landscape Association has many experts who can assist you with choosing the right plant for the right spot. A list of these individuals who reside nearest to you can be found in the membership section on this web site. You may also view past articles here.