Ivy geraniums, known botanically as Pelargonium peltatum, are flowering perennials that do not tolerate heavy frost or freezing temperatures. They are grown as annuals or overwintered indoors in climates cooler than USDA Zone 8. They have a slightly cascading growth habit and deep green leaves reminiscent of trailing ivy. They are often used in hanging planters, terrace or window boxes, or to cascade over walls, and will extend up to 3 feet or so from the main stem. They require a temperate climate and full sun, though afternoon shade is needed in warm climates where temperatures rise above 80 degrees F.
Soil Requirements for Container Plantings
Supply a light potting mix for ivy geraniums grown in containers, and refrain from using heavy garden soil with clay that can suffocate the roots. Blend garden soil with equal measures of peat moss and perlite to ensure an easy-draining, airy soil that can still hold some moisture. Add 1/2 teaspoon of a slow-release complete garden fertilizer with a 5-10-5 or 6-12-12 analysis to the container soil at planting.
Soil Requirements for Ground Plantings
Provide ground garden soil for your ivy geraniums that is nutrient-rich and friable, well-drained, and amended with properly aged livestock manure and compost. They enjoy a lightly acidic soil around 6.5pH, so amend alkaline or overly acidic soil to bring it into the range of the optimal pH level. Till the soil well at planting time, and mulch around the plants with an organic material to keep the roots cool in spring and summer, and warm in winter when grown as perennials in USDA Zones 8 and above.
Applied Fertilizer Nutrients
Ivy geraniums are vigorous growers and benefit from regular applications of nitrogen-rich, slow-release fertilizer applied monthly to the soil during spring and summer, and every other month in fall and winter whether grown outdoors as perennials in USDA Zone 8 and above or overwintered indoors in Zones 7 and below. Fertilizer keeps the leaves a deep green, prevents yellowing and promotes vigorous trailing growth.
Feed an organic or chemical slow-release fertilizer with a guaranteed analysis of 10-10-10 or 8-8-8. Apply up to 2 pounds of fertilizer for every 100 square feet of planting soil surface, which equates to 1 rounded teaspoon for every square foot in container or smaller bedding plantings.