Hardy geraniums, commonly known as cranesbills, are perennial plants belonging to the Geranium genus, a distinction that sets them apart from the annual bedding plants often sold as “geraniums.” These popular annuals are actually Pelargoniums and are not frost-tolerant. True hardy geraniums are valued in perennial gardens for their vigor, extended bloom time, and general adaptability across a wide range of climates. Understanding the optimal time to place these plants in the ground is the first step toward ensuring their successful establishment.
Optimal Timing for Container-Grown Plants
Container-grown hardy geraniums, the most common form purchased by gardeners, offer the greatest flexibility in planting time. They can be successfully planted any time the soil is workable, meaning it is not frozen or waterlogged. This wide window is possible because the plant’s root system is already intact and established within the potting medium.
Planting in early spring, just as new growth begins, allows the plant to set deep roots before the stress of summer heat arrives. The cooler temperatures and reliable spring rains provide an ideal environment for root expansion without demanding excessive watering.
An alternative beneficial period is early fall, after the peak heat of summer has passed. Fall planting allows the roots to continue developing in the still-warm soil before winter dormancy. While planting during the high heat of summer is possible, it requires significantly more attention to watering to ensure the roots do not dry out.
When to Plant Dormant Bare Roots
Planting hardy geraniums sold as dormant bare roots requires a more restrictive and precise timing window than container-grown stock. The key to success is placing the roots in the ground while the plant is still fully dormant or just beginning to break dormancy. This ensures the plant dedicates its initial energy to root development rather than supporting new foliage.
The primary window for bare root planting is very early spring, immediately after the ground thaws and before the last expected hard frost. This timing mimics the natural cycle of the plant, allowing it to awaken with the season and establish a robust root system early on.
A secondary option is to plant in the late fall. For late fall planting, the bare roots should be installed at least six weeks before the first hard ground freeze is anticipated. This duration allows enough time for the roots to settle into the soil before winter dormancy completely halts all growth processes.
Preparing the Site and Planting Procedure
Success with hardy geraniums starts with selecting the right location, which typically involves full sun to partial shade exposure, depending on the specific variety. In regions with intense afternoon heat, providing some shade during the hottest part of the day can prevent leaf scorch and prolong blooming.
The soil should be well-drained and of average fertility, as highly rich soil can sometimes promote excessive foliage growth at the expense of flower production. Good drainage is paramount, as hardy geraniums are intolerant of consistently wet conditions, which can lead to crown rot.
If your soil is heavy clay, amending it deeply with a generous amount of organic matter, such as compost, will improve the soil structure and aeration. An ideal soil pH for most varieties is slightly acidic to neutral, typically falling between 6.0 and 6.5.
The physical planting procedure is straightforward for both container and bare root plants. Dig a hole that is approximately twice as wide as the root ball or the spread of the bare roots, but no deeper. This wider hole allows the roots to easily spread into the loosened surrounding soil.
For container plants, gently remove the plant and set it into the prepared hole so that the top of the root ball’s soil is level with the surrounding garden soil. For bare roots, create a small mound of soil in the center of the hole and spread the roots evenly over this mound.
Backfill the hole with the amended soil, lightly firming it around the roots to eliminate any air pockets. Finally, provide a thorough, deep watering to settle the soil and immediately begin hydrating the newly placed plant.