Geraniums are popular bedding plants, frequently purchased in containers to provide season-long color in the landscape. Gardeners often wonder if these container-grown favorites can be successfully moved into the garden bed for the summer. The transition from a pot environment to the open ground requires careful consideration of the plant’s needs and specific planting techniques. This guide clarifies which type of geranium thrives in the ground and how to ensure a successful establishment and growing season.
Understanding Which Geranium You Have
The success of planting a geranium depends entirely on which species you have, as two different groups share this common name. The bright, showy annuals sold in garden centers are members of the genus Pelargonium, originating from warm climates. These are tender plants that cannot tolerate frost and are typically treated as annuals in most temperate zones. They should only be moved into the ground once all danger of freezing temperatures has passed.
The other group, commonly referred to as true geraniums or cranesbill, belongs to the genus Geranium. These species are hardy perennials, capable of surviving harsh winters and returning reliably. True geraniums are significantly more cold-tolerant than Pelargoniums and are permanent landscape fixtures. This guide focuses on the popular, frost-sensitive Pelargonium variety, which requires specific care for successful summer ground planting.
Selecting the Right Location and Soil
Once you confirm you have a Pelargonium, selecting the proper planting site is necessary to ensure robust growth. These plants thrive in locations that receive full sun, meaning at least six hours of direct sunlight daily is necessary for abundant flowering. In regions experiencing intense summer heat (regularly exceeding 90 degrees Fahrenheit), protection from the harsh afternoon sun is beneficial. A location offering morning sun and filtered afternoon shade can prevent leaf scorch and heat stress.
Soil composition is equally important for the health of ground-planted geraniums. They require excellent drainage because they are highly susceptible to root rot, often called “wet feet.” Heavy clay soil should be amended with organic materials like compost or coarse sand to improve aeration and water percolation. Geraniums prefer a soil pH that is slightly acidic to neutral, ideally ranging between 6.0 and 7.0. The planting site should allow for proper spacing between individual plants, typically 10 to 12 inches apart. This distance promotes air circulation around the foliage, which helps defend against fungal diseases such as botrytis blight.
Planting Techniques and Establishment
Before transplanting potted Pelargoniums into the garden bed, they must undergo hardening off. This involves gradually introducing the plants to outdoor conditions over seven to ten days, slowly increasing their exposure to direct sun and wind. This acclimatization prevents shock, which manifests as immediate wilting, burnt leaf margins, or a stall in growth.
When you are ready to plant, dig a hole that is approximately twice as wide as the current root ball but no deeper. If the roots are compacted or circling tightly, gently loosen them with your fingers to encourage outward growth into the native soil. Place the plant so the top of the root ball is level with the surrounding garden soil. Planting too deep can bury the crown, often leading to stem rot and subsequent plant failure.
Backfill the hole with the amended soil, pressing gently around the base of the plant to eliminate air pockets. Immediately after planting, give the geranium a deep watering to settle the soil particles around the roots. After establishment, water only when the top one or two inches of soil feel dry, avoiding overhead watering that keeps the foliage damp. Avoid high-nitrogen fertilizers at this stage, as they promote leafy growth over root establishment and flowering.
Preparing Geraniums for Winter
Since Pelargoniums are tender tropical plants, plans must be made before the first hard frost arrives. Gardeners have two choices: treat them as annuals and allow the frost to terminate the plant, or attempt to overwinter them indoors. Overwintering allows the same plant to be used again the following spring, preserving specific varieties.
To save the plants, they must be brought inside well before the ground freezes. One method is to dig up the plants, prune them back by about one-third, and repot them into containers. Alternatively, the plants can be stored bare-root in a dormant state. This involves shaking off most of the soil and hanging the plants upside down in a cool, dark, and dry location where temperatures remain above freezing.