Ivy Geranium (Pelargonium peltatum)

Ivy geranium was first introduced to Europe by the governor of the Cape Province in the eighteenth century. The genus Pelargonium derives its name from the beak of a stork because of its fruits’ resemblance to it.

I. Appearance and Characteristics 

Pelargonium peltatum is known by several common names including ivy-leaved pelargonium and cascading geranium. It is native to the Cape Provinces of South Africa.

The ivy-leaved pelargonium is a perennial plant that scrambles over the surrounding vegetation and its somewhat succulent, slender and smooth, 3–10 mm (0.12–0.40 in) thick stems can grow to a length of about 2 m (7 ft).

The leaves are alternately arranged along the stem, but sometimes seem to be opposite. The leaves have broad oval to triangular stipules of about 7 mm (0.28 in) long and 4 mm (0.16 in) wide, a leaf stalk of ½–5½ cm (0.2–2.2 in) long, and a hairy or hairless, green to greyish green, sometimes with a differently colored semicircular band, more of less fleshy, circular to heart-shaped in outline, on average 3 cm (1.2 in) long and 5 cm (2.0 in) wide (full range 1–6¾ cm × 1¾–8¾ cm). The leaf blade has five shallow or deeper sharp or blunt tipped lobes that spread radially from a point with an entire margin.

Flowers

The umbel-like inflorescences sit atop a stalk of about 6 1⁄2 cm (2.6 in) long (full range 4–8 1⁄2 cm) covered with long soft hairs to hairless. At the top of the inflorescence stalk are long, softly hairy, oval to lance-shaped bracts of about 3 mm (0.12 in) long and 2 mm (0.08 in) wide, which subtend two to ten scentless flowers, each on a long softly hairy flower stalk of 1¾–5 mm (0.07–0.20 in) long. The long, softly hairy floral tube, which is somewhat difficult to distinguish from the flower stalk, is on average 3 cm (1.2 in) long (full range 2–4¼ cm). The five free, purple to light green sepals are lance-shaped, covered in long, soft hairs on the surface facing out, on average 11 mm (0.44 in) long (full range 7 1⁄2–14 mm). The five free petals are spade-shaped, and whitish, pale pink, pinkish mauve or mauve in colour.

The two upper petals sometimes have purple markings, curve back at an approximate angle of 90° and are on average 21 mm (0.85 in) long and 9 mm (0.35 in) wide (full range 15–27 mm × 6–12 mm). The three lower petals curve back slightly and are on average 17 mm (0.65 in) long and 6 mm (0.25 in) wide (full range 13½–21 mm × 3½–7½ mm). The ten filaments are merged into a tube of about 2 mm (0.08 in) long, the free parts of the filaments varying in length within the same flower, between 2 and 11 mm (0.08–0.45 in) long. Only five to seven of the filaments carry a purple, about 2 mm long anther, even in freshly opened flowers (anthers are quickly lost), the upper two on much shorter filaments.

The wooly hairy ovary is about 4 mm (0.16 in) long that is topped by a hairy or hairless, about 5 mm (0.2 in) long style that carries five stigmas of about 3 mm (0.12 in) long. These female floral parts develop into a dry splitting fruit, the five parts each consisting of an approximately 7 mm (0.28 in) long, roughly hairy oval base and an about 3 cm (1.2 in) long tail. The bases of these mericarps each contain one hairless, brown, ellipse-shaped seed of about 5 mm long and 2 mm in diameter.

P. peltatum has nine homologous sets of chromosomes (2x=18).

II. Types of Ivy Geranium

More than 75 named cultivars of ivy geraniums are available with new ones introduced every year. Some recent favorites include:

• ‘Crocodile’ ivy geranium plants have unique foliage with white veins.
• ‘White Mesh’ has green leaves with bright white veins.
• ‘Royal Amethyst’ has early lilac flowers on heat-resistant plants.
• ‘Temprano Butterfly’ is bright pink with a high petal count.
• ‘Mahogany’ produces bicolor red and white flowers.

Some other common varieties that remain popular include: ‘Sybil Holmes’, ‘Beauty of Eastbourne’, ‘King of Balcon’, ‘Amethyst’, ‘Cornell’, ‘Salmon Queen’, and ‘Mexicana’.

III. How to Grow and Care

Sunlight

Full sun is necessary for good leaf color and flower production. Partial sun can help plants cope in regions with high summer temperatures, but four to six hours is best for ample blooming.

Temperature and Humidity

As a South African native, ivy geranium plants like moderate temperatures in the summer. A heat wave will not kill the plants, but flowering will slow or stop during the dog days of summer. You will know if the temperatures are too hot for ivy geraniums because the new leaves might look pale or even white in response to the heat.

Average to low humidity is best for ivy geraniums to thrive. High humidity can set the stage for fungal diseases.

Watering

Ivy geraniums like regular watering, but don’t like soggy conditions. Garden plants thrive on about one inch of water per week but you should allow the surface of the soil to dry out between waterings. Potted plants, however, might require watering several times a week because they dry out faster. These plants do not tolerate temporary dryness in the way that zonal geraniums do.

Soil

A loam or sandy loam provides the drainage and root aeration that ivy geraniums need. A rich soil is not as important as loose, well-drained soil. Potted plants do well in standard commercial potting mix; some growers like to mix in additional sand or perlite. Ivy geraniums like relatively neutral soil pH from 7.0 to 7.5.

Fertilizing

Ivy geraniums are not heavy feeders, but a light, continuous feeding will increase the bloom count. A convenient way to provide these nutrients is by planting ivy geraniums in potting soil that is pre-enriched with fertilizer. These potting mixes will feed plants with a slow-release fertilizer for one full growing season. Another option is to offer them a soluble plant food every two weeks when watering.2 For the amount of fertilizer to use, follow the product label instructions.

Pruning

When your ivy geranium becomes leggy, prune it back by about half. This will create a more dense, bushy plant, and will also encourage a new flush of blooms. Old plants grown as perennials in frost-free areas can become woody and might need to be cut back severely in the spring to rejuvenate.

Deadheading spent flower heads will promote new blossoms well into fall.

Propagation

Most commercial ivy geraniums have been created by asexual reproduction—by rooting stem cuttings—and this is also the best way to propagate your own plants. It can be done at almost any time, but many gardeners like to start new plants in the fall, starting them indoors to overwinter them. Here’s how to do it:

• Take a three-to four-inch cutting using scissors you have dipped in alcohol to sterilize. Remove the lower leaves.
• Dip the cutting in a rooting hormone, then plant it in a small pot filled with moistened sand.
• Place the pot in a bright location but out of direct sunlight, and keep the sand moist.
• Pot up your cutting into a larger pot filled with standard potting mix when new growth appears, after about four to six weeks. If growing the cutting indoors over the winter, give it plenty of sunlight.

How to Grow From Seed

You can grow ivy geraniums from seed collected from your plants, but you are assured of exact duplicates only if the parent is a pure species. Hybrids and named cultivars often do not come true from seed, though the results might still be interesting. However, the ‘Tornado’ series and the ‘Summer Showers’ series are two cultivars that are offered as seed.

The best method is to sow the seeds in seed flats filled with seed-starter mix under glass or plastic covers at a temperature of about 74 degrees Fahrenheit. Cover the seeds with a bare covering of fine compost—some light helps speed germination. After seedlings sprout and true leaves have formed, they can be transplanted into their own pots filled with commercial potting soil.

Seeds are best started indoors in mid to late winter. Seeds germinate in about a week and will reach flowering size in about three months.

Potting and Repotting 

Because of their long trailing habit, ivy geraniums are more commonly grown in containers rather than as garden bedding plants. It’s best to use relatively large containers that hold a good amount of commercial potting mix because the soil will retain sufficient moisture. Ivy geraniums look stunning spilling from window boxes or urn planters. The stems have a tendency to break off easily, so locate your containers away from high traffic areas where they won’t get knocked or brushed by people or animals.

When handling ivy geranium plants during the potting process, hold the plants by the root ball. Although succulent and thick, the brittle stems will snap off easily if you grasp the plant by the stem base, and you could break several stems.

If you are growing potted ivy geraniums as perennials, they will need to be repotted into larger containers every couple of years as they become root-bound. Or, you can take stem cuttings to root, then discard the older plants in favor of the new ones.

Overwintering

Because ivy geraniums are normally grown as annuals, it’s normal to simply pull them out of their pots and discard them at the end of the season. But it is also possible to grow them as perennials by bringing container plants indoors for the winter. Ivy geraniums do not make attractive year-round houseplants, but if you cut back the foliage by about one-third and find a very sunny but relatively cool location (55 degrees at night and no more than 70 degrees during the day), the plants can survive the winter and returned outdoors in the spring.

How to Get to Bloom

The prescription for great blooming ivy geraniums is relatively simple:

• At least four hours of sun daily
• Consistent moisture (not too little, not too much)
• Regular feeding, either through time-release fertilizer mixed with the soil or a light feeding with water-soluble fertilizer every two weeks
• Deadhead and pinch back stems to stimulate new growth and more flowers

Pests and Diseases

Common Pests & Plant Diseases

Ivy geraniums are largely trouble-free when grown outdoors where air circulation is good, but when potted plants are brought indoors to overwinter, a variety of common pests can appear, including mealybugs, spider mites, thrips, and fungus gnats. Insecticidal soaps or neem oil can effectively treat these pests.

Leaf spot fungal disease can afflict overwatered plants, especially in poorly ventilated spaces.

Common Problems 

Ivy geraniums are prone to one notable disorder—oedema which is caused by varying moisture levels. Oedema causes the plant to develop corky spots on the underside of older leaves, caused by rupturing plant cells. If you see this symptom, adjust your watering schedule to irrigate more often but in smaller quantities.

Older plants can get woody and sparse over time. If so, simply prune them back severely and wait for new growth to fill in. This is most common with potted plants that move between indoor and outdoor locations over several years. Woody growth can also be a sign that the plants need to be repotted into larger containers.

III. Uses and Benefits 

• Ornamental uses

Ivy geranium is a great candidate for beds and borders, Mediterranean gardens, containers, hanging baskets, and window boxes. It also makes a great ground cover too.

• Culinary uses

The leaves of the ivy-leaved pelargonium can be eaten as a vegetable and have a tangy taste.

• Other uses

A bluish textile dye can be made from the petals.