Geranium: Care and Growing Guide

The geranium name: two very different plants

When Americans say “geranium,” they usually mean one of two unrelated plants. Getting clear on which one you have determines everything about how to grow it.

Zonal geraniums (Pelargonium x hortorum): The classic window box and porch pot plant sold at every US garden center from April through June. Red, pink, white, lavender, and bicolor flowers in rounded clusters above thick, scented leaves. Originally from South Africa, this plant is not cold-hardy in the US and is grown as an annual in Zones 3–9.

True perennial geraniums (Geranium spp.): Also called cranesbill geraniums. Cold-hardy perennials, Zone 4 in most species. Smaller and more delicate than Pelargonium. They bloom heavily in spring, then produce scattered blooms through summer. Varieties include ‘Rozanne’ (the most popular), ‘Biokovo’, and ‘Johnson’s Blue’.

This guide covers both. The care is similar in many respects but the overwintering strategy is completely different.

Annual zonal geraniums (Pelargonium): care guide

Sun and soil

Zonal geraniums need a minimum of 6 hours of direct sun to bloom well. In fewer than 4 hours, they grow leggy, produce sparse blooms, and become more susceptible to Botrytis blight.

In Zones 7–9, afternoon shade from 2–4 pm reduces heat stress in July and August, when intense sun can bleach flower colors and stress the plant. East-facing exposures (morning sun, afternoon shade) work well in these hot zones.

Soil should be well-drained and moderately fertile. Geraniums actually bloom better in lean soil than in heavily amended, nutrient-rich beds — excessive nitrogen produces lush foliage at the expense of flowers. A standard potting mix works well for containers; for in-ground planting, average garden loam without heavy amendment is ideal.

Soil pH: 6.0–7.0. Geraniums are tolerant of a wider pH range than many ornamentals.

Watering

Geraniums are more drought-tolerant than most summer annuals but more susceptible to overwatering. The most common growing mistake is keeping the soil too consistently moist.

Water thoroughly when the top 1 inch of soil feels dry to the touch. Then allow it to approach dryness again before the next watering. In a typical US summer:

• Container geraniums: Water every 1–3 days depending on pot size, temperature, and sun intensity
• In-ground geraniums: Water every 4–7 days; established plants handle short drought well

Never let container geraniums sit in standing water. Drainage holes are essential. Terracotta pots are preferred by many growers — they breathe and help prevent overwatering better than plastic or glazed ceramic.

Symptoms of overwatering: yellowing lower leaves, mushy base, Botrytis gray mold on stems. Symptoms of underwatering: crispy brown leaf edges, wilting that doesn’t recover within an hour of watering.

Fertilizing zonal geraniums

The right fertilizer produces more blooms; the wrong timing produces more leaves. Use a fertilizer with a moderate-high phosphorus middle number (like 15-30-15 or a bloom booster formula) rather than a high-nitrogen balanced fertilizer.

• Container geraniums: Fertilize every 2–3 weeks from planting through August with a liquid bloom fertilizer at half the label rate; full rate risks salt buildup
• In-ground geraniums: Monthly feeding with a granular balanced fertilizer (10-10-10) through the growing season; less frequent than containers because soil buffers nutrients better
• Stop in late August: Geraniums don’t need feeding in the last month before frost; it stimulates soft growth that doesn’t harden before cold

Deadheading

Deadheading — removing spent flower clusters — is the single most effective technique for keeping geraniums blooming continuously. Left in place, spent blooms signal the plant to set seed, reducing further flower production.

Remove the entire flower stalk, not just the faded petals. Follow the stalk down to where it meets the stem and pinch or cut it there. Do this weekly during the peak bloom season (late spring through summer).

Occasional hard pinching — cutting stems back by 30–40% in late June or early July — refreshes leggy plants and stimulates a strong second flush of growth in late summer. This is especially useful for plants that have become leggy and open-centered by midsummer.

Overwintering zonal geraniums

Zonal geraniums are frost-sensitive and die at 32°F. In Zones 10–11, they grow as perennials year-round. Everywhere else, you have three options:

Option 1 — Bring indoors as a houseplant. Cut the plant back by one-third before frost, pot it up if it was in-ground, and place in a sunny south window. Water lightly through winter. It will survive and rebloom the following year. This is the most reliable method for saving a favorite variety.

Option 2 — Take stem cuttings. Take 3–4-inch cuttings from healthy stems in late summer. Remove lower leaves, allow the cut end to callous for 1 hour, then insert into a moist potting mix. Root in a bright indoor location. Cuttings root within 3–4 weeks.

Option 3 — Treat as annuals and buy new plants each spring. Most gardeners in Zones 5–7 do this. New transplants from garden centers in May are inexpensive and establish quickly.

Perennial geraniums (cranesbill): care guide

True perennial geraniums are among the most reliable low-maintenance perennials available for US gardens, Zone 4–9. They are cold-hardy, deer-resistant, drought-tolerant once established, and require almost no care beyond the occasional haircut.

‘Rozanne’ (Geranium ‘Gerwat’ Rozanne): The most popular perennial geranium in the US market. Blooms continuously from late spring through frost, which is unusual for cranesbill types. Violet-blue flowers with white centers. 18–24 inches tall and wide. Zone 4–9. AAS Winner 2008.

‘Biokovo’ (Geranium x cantabrigiense): White flowers with pink blush, early spring bloom. Only 10–12 inches tall; excellent for front of border or edging. Zone 5–9. Very drought-tolerant.

‘Johnson’s Blue’ (Geranium x magnificum): Deep lavender-blue, late spring bloom. 18 inches tall. Zone 4–8. May go summer-dormant in hot zones.

Perennial geranium care

Perennial geraniums require the “Chelsea chop” — cut them back hard by 30–50% immediately after their main spring bloom flush. This removes tired, floppy stems and triggers a second flush of growth and bloom. Without cutting, they can look messy through summer.

Companion plants for geraniums

Both types of geraniums pair well with warm-season annuals and perennials that share their sun requirements.

Zonal geraniums (containers and beds):

• Marigolds: Similar sun and water needs, complementary colors, and pest-deterring properties. Our marigold guide covers the specific French marigold types that pair best with geraniums.
• Salvia: Spiky vertical form contrasts with the rounded geranium flowers. Heat-tolerant. Our salvia guide covers varieties for US climates.
• Lantana: Excellent heat-tolerant companion in Zones 7–9. Similar water needs and complementary warm colors. Our lantana guide covers this sun-loving companion.

Perennial geraniums (garden beds):

• Hostas: Perennial geraniums on the border edge, hostas behind. The ferny geranium foliage contrasts with hosta’s bold leaves.
• Lavender: Similar lean soil preference. The combination of lavender blue and cranesbill violet is a classic cottage border pairing.
• Begonias: In shaded borders where both the cranesbill and wax begonias share part-shade tolerances. Our begonia guide covers shade-tolerant varieties.

For a broader view of which annuals bloom the longest in US gardens, our annuals that bloom all summer guide includes geraniums among the top performers for continuous summer color. Our deer-resistant flowers guide confirms both geranium types as reasonably resistant to deer browse, making them good choices for Zone 5–7 gardens where deer pressure is high.

For the full context of which sun-loving perennials perform best in US climates across Zones 4–9, our full-sun perennials guide covers the best species by bloom time, drought tolerance, and zone range — including where cranesbill geraniums fit within a larger perennial planting.

Common problems

Botrytis blight (gray mold): Fuzzy gray growth on stems or flower clusters. Caused by poor air circulation and wet conditions. Remove affected parts immediately. Improve spacing and avoid overhead watering.

Leaf spot: Small brown spots with yellow halos. Bacterial in origin. Remove affected leaves, avoid wetting foliage.

Edema: Corky, raised bumps on leaf undersides — not a disease but a physiological response to inconsistent watering (waterlogged roots combined with fast transpiration). Improve drainage and even out watering.

Aphids: Common in spring on new growth. Knock off with water spray or apply insecticidal soap. Avoid excessive nitrogen fertilizing, which produces soft growth that aphids prefer.

The Old Farmer’s Almanac geranium page provides region-specific planting calendars for both annual and perennial types across US zones. For precise hardiness zone mapping, the USDA Plant Hardiness Zone Map at planthardiness.ars.usda.gov confirms the zone designations for each cranesbill variety.