How to Grow and Care for Hardy Geranium (Cranesbill Geranium)

Hardy Geranium Care

Here are the main care requirements for growing a hardy geranium:

• Site them in a spot with full or partial sun; more sun equals more blooms.
• Give regular water, especially if in a full-sun location.
• Plant hardy geraniums so that the crown is at ground level or slightly above.
• Prune them after flowering to prompt repeated blooming into the fall.
• Prefers neutral to slightly acidic soil.
• Give well-balanced, time-released fertilizer if the soil is poor.

Light

Hardy geraniums accept a wide range of exposure conditions. For the best flowering and vigorous geranium plants, site them in full sun to partial shade.

If geraniums are grown in hot, full sun, provide regular water. Some varieties of geraniums can tolerate full shade, but they likely won't blossom as fully as those with plenty of sun.

Soil

Geraniums are not particular about soil pH, but a neutral to slightly acidic soil is ideal. Most prefer medium-moisture, well-drained soil, though some species prefer relatively dry soil.

Water

Geraniums are a low-maintenance plant, so water them only when the soil becomes dry. If located in full sun, water the plant more frequently. Hardy geraniums can become prone to fungal disease if watered overhead.

Temperature and Humidity

Hardy geraniums grow best in daytime temperatures between 65 and 75 degrees and nighttime temperatures between 50 and 60 degrees. They tolerate a wide range of humidity levels, though mildew and rust can be non-life-threatening in very humid regions.

Fertilizer

Unless the soil is very poor, hardy geraniums generally do fine with no feeding other than a yearly application of compost. Poor soils might require a spring feeding with a time-release balanced fertilizer.

Types of Hardy Geranium

There are as many as 300 types of geraniums available to grow, some pure species, others nursery-created hybrids. The pure species are popular garden plants, but many named garden cultivars originate from hybrids achieved by crossing species within the genus.

• Geranium 'Johnson's Blue': This variety is thought to be a hybrid between G. himalayense and G. pretense. It is one of the most popular varieties, growing about 18 inches tall with sky-blue flowers. It is suitable for zones 4 to 8.
• G. sanguineum: This species, sometimes known as bloody cranesbill, is a relatively low-growing, clumping form that produces reddish-purple flowers from May to June, with lesser flowering into the late summer. It is grown in zones 3 to 9. Several good cultivars are available: 'Album,' with white flowers; 'Elke,' with soft pink flowers; and 'New Hampshire Purple,' with violet flowers with white eyes.
• G. himlayense: Known as lilac cranesbill, this species is hardy in zones 4 to 8 and produces violet, indigo, and blue flowers in early to mid-summer. It grows 9 to 18 inches in height.
• Geranium × oxonianum' Wargrave Pink': The most commonly grown geranium with salmon-pink flowers grows 18 to 24 inches tall in zones 3 to 8.
• Geranium' Rozanne: A violet-blue hybrid that flowers almost non-stop throughout summer. It grows 18 to 24 inches tall in zones 5 to 8.
• Geranium 'Ann Folkard': This is one of the earliest blooming geraniums with magenta flowers that repeat bloom throughout the season. This hybrid has a trailing habit and grows six to eight inches tall in zones 5 to 9.
• Geranium 'Double Jewel': Double-white petals feature a lilac center. It's short and sometimes grown containers because it grows 10 inches tall. It is hardy in zones 4 to 8.
• Geranium 'Southcombe Double': Double, pure pink blooms resemble fluffy asters. It grows ten inches tall in zones 4 to 8.
  

Pruning

Hardy geraniums require little care once established. They can get scraggly after blooming, and deadheading is difficult because of its many wispy stems. Shearing the plants back to basal growth will improve their look and encourage re-blooming.

The plants fill out within weeks. The exception is G. macrorrhizum, which is easily deadheaded and needs no shearing.

Propagating Hardy Geraniums

Cranesbill geraniums can be divided and replanted through early summer. Nursery plants or divisions will quickly reach flowering maturity within their first year and slowly spread to fill available space. Plants started from seed can take several years before they flower.

Most species of hardy geranium live longer if divided every three to five years, though you can divide more frequently to keep them from spreading or to obtain new plants. Once you see the center dying out, it is time to divide.

Divide the geraniums from early spring to early summer, giving the plant time to establish roots before a frost. Here's how:

1. Begin by digging up the plant and shaking the soil off the roots.
2. Use a trowel or a knife to separate the root ball into pieces, ensuring each division has a root section and leaves.
3. Replant each divided section at its original depth.
4. Thoroughly water the newly planted divisions.
   

How to Grow Hardy Geraniums From Seed

Many hardy geraniums will self-seed readily, even taking root in sidewalk cracks. They do not spread uncontrollably and are rarely a problem. The volunteer seedlings can be easily dug up and transplanted elsewhere. You can also collect and plant seeds in the garden or seed-starter trays.

Hybrids and many cultivars do not come true from collected seeds; these must be propagated by root division or other vegetative methods. Hardy geraniums are relatively slow-growing plants, and when started from seeds, it can take three to five years before they are mature enough to flower.

Here's how to plant from seed:

1. Get planting cells or 2-inch pots filled with moistened potting soil.
2. Lightly cover one seed per pot or cell with soil.
3. Cover the pot with clear plastic to keep the soil humid to promote germination.
4. Keep the pot in a warm spot, at least 75 F, with bright, indirect light.
5. Keep the soil moist.
6. Germination can take place within three days or three weeks, depending on the conditions.
7. Uncover the plastic and give half-strength fertilizer once a seedling emerges.
   

Potting and Repotting Hardy Geraniums

Unlike the popular zonal geraniums (Pelargonium), hardy geraniums are perennial plants rarely grown in containers. That said, there's no reason you can't do it. Use an oversized pot that will give the plant plenty of space to grow, and fill it with any standard commercial potting mix.

The container can be made of any material but must have good drainage. Spread out the roots of the geranium as you plant it.

Hardy geraniums don't like waterlogged soil, so weekly watering should suffice. They are relatively slow-growing plants, so repotting is required only when roots begin to poke out the drainage holes—this can take as long as three years.

In colder climates, move the pots to a sheltered spot for the winter to protect the roots. These plants are not suitable for moving indoors to grow as houseplants.

Overwintering

Hardy geraniums generally require no winter protection against cold, but it is good practice to cut off the stems to just above ground level and discard the debris as winter approaches to eliminate fungal spores that can often cause powdery mildew.

Common Pests & Plant Diseases

Hardy geraniums are relatively trouble-free plants. Slugs might attack young geranium plants, while mildew and rust can infest foliage, especially in partial shade and humid climates. Shearing back and disposing of the infected leaves will help.

To avoid mildew, give the plants plenty of space to improve air circulation and water through ground soaking rather than overhead spraying. Mildew spores are spread from water splashing against the soil.

How to Get Hardy Geranium to Bloom

When hardy geraniums fail to bloom as you expect, it's usually for one of these reasons:

• Too much moisture: Most hardy geraniums like relatively dry conditions; if they are overwatered, they will withhold blooms.
• Not enough sun: These plants typically want at least six hours of sun daily, and if they don't get it, flowering will be more sparse. The foliage itself, though, is often appealing enough to warrant growing the plant even in relatively shady conditions.
• Too much fertilizer: These plants thrive on little to no fertilizer, and if fed too often, the result can be excessive foliage at the expense of flowers. Fertilizers heavy in nitrogen are especially problematic.
• Replanted too deep: When replanting into a larger container or in a new site, do not replant them too deep; it can prevent them from flowering.
  

Bloom Months

Hardy geraniums typically bloom from May to September, generally from early summer to early fall.

How Long Does Hardy Geranium Bloom?

Hardy geraniums bloom for about three months. Often, there is one particularly heavy flush of flowers, with fewer blooms continuing in subsequent months. Shearing back plants after the main flush frequently stimulates more blooms to follow.

What Do Hardy Geraniums Flowers Look and Smell Like?

The flowers are five-petalled, usually pink, purple, blue, or white. Some have a mild, pleasant scent, if at all.

Deadheading Hardy Geranium Flowers

Most geraniums are wispy and difficult to deadhead. It's best to shear the plants to the base after flowering to promote more blooms to appear. The only hardy geranium worth deadheading is Geranium macrorrhizum, which is easy to deadhead.

Common Problems with Hardy Geranium

Hardy geraniums don't need much to grow well, but they do have some issues that come up occasionally.

Overgrowth

Hardy geraniums spread easily in the garden as a pleasing ground cover that weaves among other plants to block weeds and can grow somewhat invasively, spreading via underground rhizome rooting structures. Fortunately, hardy geranium is relatively easy to dig out and eliminate.

Leggy Growth

After flowering, hardy geraniums can become somewhat leggy and sparse. It's easy to shear or cut back the sparse stems, stimulating new growth.