Companion Plants for Geraniums
Companion planting is a broad-ranging topic that might be based on science for some suggested pairings but is more likely to be anecdotal or assumed.
Many growers use the term "companion planting" so loosely that it relates merely to attractive combinations, but companion planting usually refers to plants that, when planted in close proximity, improve each other’s health by dissuading pests, attracting pollinators or providing nutrients. At the least, companion planting should pair plants that require the same growing conditions.
In the case of both hardy and garden geraniums, little evidence suggests that any particular pairing benefits either the geranium or the selected companion plant, with a few exceptions. Nonetheless, some recommended combinations make sense from a growing perspective and might also make an attractive garden bed.
About Geraniums: Hardy or Annual
Geraniums come in two primary flavors: the annual geranium, also called “zonal geranium” or “garden geranium” (Pelargonium spp.) sold in most nurseries, and the true geranium (Geranium spp.), referred to as “hardy geranium” or cranesbill.
Both the Geranium and the Pelargonium genera belong to the Geraniaceae family, but species in the Pelargonium genus are hardy only in USDA zones 9 to 12, while many in the Geranium genus grow in zones as cold as hardiness zone 3.
Annual geraniums are those typically found in nurseries during the growing season. They are stars in any garden for their color, low maintenance and versatility. Geraniums are popular for container gardening, and gardeners commonly grow geraniums in hanging baskets, flowerbeds and borders.
Annual geraniums typically have a bushy habit, but hybridization has produced hundreds of varieties and cultivars that range widely in size, flower color and leaf shape.
Hardy Geraniums (Cranesbill)
Hardy geraniums reliably return year after year, and most species can handle either full sun or partial shade, although they produce more flowers in sun. The more than 300 species range from 6 to 24 inches in height. Some spread out in a sprawling fashion, while some stand upright in big mounds.
Plant them in well-draining soil, taking care not to cover the crown with soil. As hardy perennials, they will return each year. They need little care and are drought tolerant once established.
Geranium Companion Planting
Geranium companion planting is usually recommended for pest control, but it can also be effective in attracting pollinators.
Companion Planting for Pest Control
Both amateur gardeners and extension experts widely consider geraniums to be effective as a form of pest control in vegetable gardens, while some common geranium pairings have been found to do more harm than good. Here’s a rundown:
- Cabbage worms: Yes, it’s not just lore. Most experts agree that—similar to marigolds—zonal geraniums can repel cabbage worms, which are common pests that target vegetables in the Brassica family, such as cabbage, broccoli and kale. Plant geraniums in the same bed as these types of vegetables if these worms are a problem.
- Japanese beetles: This is a tough one because zonal geraniums have long been thought to repel Japanese beetles, and some university extension experts, including those at California Lutheran University, recommend it as a pest control strategy. However, this has been debunked by several studies, including one by the University of Kentucky. The study, reported in the Journal of Economic Entomology, found that the presence of zonal geraniums actually increased the number of Japanese beetles. For this reason, avoid planting geraniums near roses, grapes, beans, apples, raspberries and other plants that are susceptible to this pest.
- Leafhoppers: Zonal geraniums, along with petunias, act to repel leafhoppers, which are common pests of many vegetable crops. Plant them near eggplant, beans, carrots, celery, lettuce, parsley, parsnips and potatoes to deter these pests.
Companion Planting for Pollinators
For fruits and vegetables to produce crops, they need pollinators. Effective companion planting should incorporate plants that attract important pollinators. Common pollinating insects include bees, moths, butterflies, beetles and some flies.
While zonal geraniums are not known for attracting bees—due to their complex flower structure that makes it tough for bees to access nectar and pollen—one study performed at the University of Pennsylvania concluded that several zonal geranium cultivars were effective at attracting bees, including Savannah Pink Sizzle, Savannah White Splash and Pacific Violet.
Unlike zonal geraniums, perennial geraniums are typically all effective at attracting pollinators. Plant these near your fruit trees and veggies to improve yields.
- Virginia Polytechnic Institute and State University: JARS v50n3 - Companion Plants: Hardy Geraniums
- University of Connecticut Extension: Sustainable Edible Landscapes
- Cornell University: Companion Planting and Flower Borders
- Iowa State University: Perennial Geraniums or Cranesbills
- San Diego Geranium Society: Growing Zonal Geraniums
- University of Wisconsin Madison: Ask a Master Gardener – Hardy Geraniums: A Year Round Splendor
- California Lutheran University: Alternative and Sustainable Pest Management
- Journal of Economic Entomology: Evaluating Companion Planting and Non-Host Masking Odors for Protecting Roses
- Cornell University: Companion Planting
- Pennsylvania State University: Identifying “Pollinator-Friendly” CUultivars for Gardens and Greenroofs
- Clemson University: Pollinator Gardening
- Oregon State University: 25 Plants for Attracting Native Bees to the Garden
I garden in the Pacific North west, previously Hawaii where I had an avocado orchard. I have a Master Gardeners certificate here in Eugene, Oregon.