Geranium (Pelargonium)

Geraniums, also commonly known as cranesbills and storksbills, are a beloved garden staple, boasting vibrant blooms and a variety of uses. Their botanical name, Pelargonium (for many common garden varieties) or Geranium (for hardy, perennial types), hints at their diverse family, encompassing a range of colors, foliage, and growth habits. This comprehensive guide, brought to you by Gardencenterpoint.com, will unlock the secrets to successfully cultivating these versatile plants.

We’ll delve into everything from essential geranium care techniques to exploring the fascinating world of geranium types. Keep reading to unearth a treasure trove of information to help your geraniums, or pelargoniums, flourish and add lasting beauty to your garden, whether you want to buy geranium plants online or learn about geranium diseases.

Understanding Geraniums: A Comprehensive Overview

Geraniums are flowering plants favored by gardeners for their long blooming season, vibrant colors, and relatively easy care. But the term “geranium” can be a bit confusing. It actually refers to two related genera: Pelargonium and Geranium.

• Pelargonium: Most plants commonly called “geraniums” are actually Pelargoniums. These are the zonal geraniums, ivy geraniums, scented geraniums, and regal (Martha Washington) geraniums. They are typically treated as annuals in colder climates, although they are technically tender perennials. They are native to South Africa.
• Geranium: This genus includes the “true” or “hardy” geraniums, also known as cranesbills. These are perennial plants that are much more cold-hardy than Pelargoniums. They are native to temperate regions around the world.

Key Differences:

Feature	Pelargonium (Common Geranium)	Geranium (Cranesbill)
Cold Hardiness	Tender Perennial (often Annual)	Hardy Perennial
Native Region	South Africa	Temperate Regions
Bloom Time	Long, often continuous	Spring/Summer
Flower Appearance	Showy, often clustered	More delicate, 5 petals
Leaf Shape	Variable, often rounded/lobed	Deeply divided

Common name	Geranium, Cranesbill, Storksbill
Botanical name	Pelargonium spp. (most common garden types) and Geranium spp. (hardy geraniums/cranesbills)
Family	Geraniaceae
Genus	Pelargonium / Geranium
Species	Numerous species and cultivars within both genera. Examples: Pelargonium x hortorum (zonal geranium), Pelargonium peltatum (ivy geranium), Geranium sanguineum (bloody cranesbill)
Origin	Pelargonium
Native	Depends on Species
Life cycle	Pelargonium: Tender Perennial (often grown as an Annual). Geranium: Hardy Perennial.
Plant type	Herbaceous, some semi-woody (Pelargonium), some with rhizomes (Geranium)
Hardiness zone	Pelargonium: Typically 9-11 (grown as annuals in colder zones). Geranium: Varies widely, many are hardy to zones 3-8.
Sunlight	Full Sun (6-8 hours) for most. Pelargonium domesticum (Regal/Martha Washington) prefers some afternoon shade in hot climates. Some Geranium species tolerate partial shade.
Maintenance	Low to Medium. Deadheading and occasional pruning.
Water	Moderate. Allow soil to dry slightly between waterings. Avoid overwatering.
Drainage	Well-Drained
Spacing	12-24 inches apart, depending on variety and growth habit.
Flowering period	Pelargonium: Spring to Frost (often continuous). Geranium: Spring to Summer (some rebloom).
Height	Varies widely. 6 inches to 3 feet, depending on species and cultivar.
Growth rate	Moderate to Fast.
Flower color	Red, Pink, White, Purple, Salmon, Orange, Bicolors.
Stem color	Green, sometimes reddish or brownish.
Flower benefit	Long Bloom Season (especially Pelargonium), Attracts some pollinators (especially Geranium).
Garden style	Container, Cottage, Rock Garden, Border, Hanging Basket (for trailing types).
Uses	Ornamental, Container Plant, Hanging Basket, Bedding Plant, Groundcover (some Geranium), Scented Leaves (some Pelargonium), Cut Flower (limited use).
Soil pH	6.0 to 6.5 is ideal.
Propagation	Stem Cuttings, seeds.
Fertilizer	Balanced, water-soluble or slow release.
Pest	Aphids, Whiteflies, Spider Mites, Mealybugs.
Diseases	Botrytis Blight, Bacterial Blight, Root Rot, Rust.
Deer Resistance	Yes.
Toxicity	Mildly toxic to pets if ingested in large quantities. The primary toxic compounds are geraniol and linalool.

Why Grow Geraniums?

Geraniums offer a multitude of benefits for gardeners:

• Long Blooming Season: Many Pelargonium varieties bloom continuously from spring until frost.
• Variety of Colors: Geraniums come in a vast array of colors, including red, pink, white, purple, salmon, and even bi-colors.
• Easy to Grow: Geraniums are relatively low-maintenance plants, making them suitable for both beginner and experienced gardeners.
• Versatile: They can be grown in containers, hanging baskets, window boxes, and garden beds.
• Deer Resistant: Geraniums are generally not favored by deer.
• Some have fragrant foliage: Scented geraniums release a pleasant aroma when brushed against, with scents ranging from lemon and rose to peppermint and nutmeg.
• Pollinator Friendly: While not the biggest attractors, some geranium varieties, particularly the true geraniums (Cranesbills), provide nectar and pollen for bees and other beneficial insects.

A study published in the Journal of the American Society for Horticultural Science confirmed the adaptability of zonal geraniums to various environmental conditions, highlighting their resilience and suitability for diverse garden settings.

Essential Geranium Care: A Step-by-Step Guide

1. Sunlight:

• Geraniums thrive in full sun, requiring at least 6-8 hours of direct sunlight per day.
• In extremely hot climates, some afternoon shade may be beneficial to prevent leaf scorch.
• Insufficient light will result in leggy growth and reduced flowering.

2. Soil:

• Well-draining soil is crucial for geraniums. They do not tolerate soggy conditions.
• A good potting mix for containers should include peat moss, perlite, and vermiculite.
• For garden beds, amend heavy clay soil with compost or other organic matter to improve drainage.

3. Watering:

• Water geraniums thoroughly when the top inch of soil feels dry to the touch.
• Avoid overwatering, which can lead to root rot.
• Water at the base of the plant to avoid wetting the foliage, which can promote fungal diseases.

4. Fertilizing:

• Geraniums are moderate feeders.
• Use a balanced, water-soluble fertilizer every 2-4 weeks during the growing season.
• Alternatively, use a slow-release fertilizer at planting time.
• Reduce or stop fertilizing during the winter months when growth slows.

5. Deadheading:

• Regularly remove spent flowers (deadheading) to encourage continuous blooming.
• Simply pinch or snip off the faded flower stalks just below the flower head.

6. Pruning:

• Prune geraniums to maintain their shape and encourage bushier growth.
• Pinch back the growing tips of young plants to promote branching.
• Cut back leggy stems to rejuvenate the plant.

7. Overwintering (for Pelargoniums):

• In colder climates, Pelargoniums can be overwintered indoors.
• Before the first frost, bring the plants inside and place them in a bright, cool location (around 50-60°F).
• Water sparingly during the winter.
• Alternatively, take cuttings in late summer and root them indoors to start new plants for the following spring.

Types of Geraniums: Exploring the Diversity

The world of geraniums is incredibly diverse. Here are some of the most popular types:

• Zonal Geraniums (Pelargonium x hortorum): The most common type, known for their rounded leaves with dark, circular zones or bands. They come in a wide range of colors and are excellent for containers and beds.
  • Example Cultivars: ‘Maverick’, ‘Pinto’, ‘Orbit’
• Ivy Geraniums (Pelargonium peltatum): Trailing geraniums with ivy-shaped leaves. Ideal for hanging baskets and window boxes. They prefer slightly cooler temperatures than zonal geraniums.
  • Example Cultivars: ‘Cascade’, ‘Summer Showers’, ‘Global Stars and Stripes’
• Regal Geraniums (Pelargonium domesticum): Also known as Martha Washington geraniums, these have large, showy flowers with intricate patterns and often ruffled petals. They prefer cooler temperatures and more shade than other Pelargoniums.
  • Example Cultivars: ‘Aztec’, ‘Elegance’, ‘Grand Slam’
• Scented Geraniums (Pelargonium species and hybrids): Grown for their fragrant foliage, which releases a variety of scents when touched. The leaves can be used in potpourri, sachets, and even cooking.
  • Example Cultivars: ‘Attar of Roses’ (rose scent), ‘Lemon Fizz’ (lemon scent), ‘Chocolate Mint’ (mint scent)
• Hardy Geraniums (Cranesbills – Geranium species and hybrids): Perennial plants that are cold-hardy and return year after year. They have delicate, five-petaled flowers and deeply divided leaves.
  Example Cultivars: Geranium ‘Rozanne’ (long-blooming blue), Geranium sanguineum (bloody cranesbill), Geranium maculatum* (wild geranium)

Choosing the Right Geranium:

Consider the following factors when selecting geraniums:

• Climate: Choose hardy geraniums (Geranium) for cold climates and Pelargoniums for warmer climates (or treat them as annuals).
• Sunlight: Most geraniums prefer full sun, but regal geraniums prefer some shade.
• Location: Use zonal geraniums for beds and containers, ivy geraniums for hanging baskets, and scented geraniums for sensory gardens.
• Flower Color and Form: Choose colors and flower shapes that appeal to your personal preference.

Propagating Geraniums: Creating New Plants

Geraniums are relatively easy to propagate, allowing you to expand your collection or share plants with friends. There are two main methods:

1. Stem Cuttings:

• Timing: Take cuttings in spring or late summer.
• Materials: Sharp knife or pruners, rooting hormone (optional), potting mix, small pots.
• Steps:
  1. Cut a 4-6 inch stem from a healthy plant, just below a node (where a leaf joins the stem).
  2. Remove the lower leaves, leaving only a few at the top.
  3. Dip the cut end in rooting hormone (optional).
  4. Insert the cutting into a pot filled with moist potting mix.
  5. Place the pot in a bright, indirect location.
  6. Keep the soil consistently moist, but not soggy.
  7. Roots should develop in 3-4 weeks.
  8. Once rooted, transplant the cutting into a larger pot or the garden.

2. Seed Propagation:

• Timing: Sow seeds indoors 8-10 weeks before the last expected frost.
• Materials: Seed starting mix, seed trays, heat mat (optional), grow lights (optional).
• Steps:
  1. Fill seed trays with moist seed starting mix.
  2. Sow seeds thinly on the surface of the mix.
  3. Lightly cover the seeds with a thin layer of mix.
  4. Water gently.
  5. Place the trays in a warm location (70-75°F) with bright, indirect light.
  6. A heat mat can help speed up germination.
  7. Keep the soil consistently moist.
  8. Germination typically occurs in 1-3 weeks.
  9. Once seedlings have developed a few sets of true leaves, transplant them into individual pots.
  10. Harden off the seedlings before transplanting them outdoors.

Geranium Diseases and Pests: Prevention and Control

Geraniums are generally hardy plants, but they can be susceptible to certain diseases and pests.

Common Diseases:

• Botrytis Blight (Gray Mold): A fungal disease that causes gray, fuzzy growth on leaves, stems, and flowers. It thrives in cool, humid conditions.
  • Prevention: Provide good air circulation, avoid overhead watering, and remove affected plant parts.
  • Treatment: Fungicides containing copper or sulfur can be used.
• Bacterial Blight: A bacterial disease that causes water-soaked spots on leaves, which eventually turn brown and dry.
  • Prevention: Avoid overhead watering, provide good air circulation, and use disease-free plants.
  • Treatment: Remove affected plant parts. There is no effective chemical treatment for bacterial blight.
• Root Rot: A fungal disease that occurs in poorly drained soil. Symptoms include yellowing leaves, wilting, and stunted growth.
  • Prevention: Use well-draining soil and avoid overwatering.
  • Treatment: Improve drainage and allow the soil to dry out between waterings. In severe cases, the plant may need to be discarded.
• Rust: Identified by orange or brown pustules on the undersides of leaves.
  • Prevention: Good air circulation and avoid wetting foliage.
  • Treatment: Fungicides; remove and destroy affected leaves.

Common Pests:

• Aphids: Small, soft-bodied insects that suck sap from leaves and stems. They can cause distorted growth and transmit viruses.
  • Control: Spray with insecticidal soap or neem oil. Introduce beneficial insects like ladybugs.
• Whiteflies: Tiny, white insects that fly around when disturbed. They also suck sap and can cause yellowing leaves.
  • Control: Spray with insecticidal soap or neem oil. Use yellow sticky traps.
• Spider Mites: Tiny pests that are difficult to see with the naked eye. They cause stippling and webbing on leaves.
  • Control: Increase humidity, spray with insecticidal soap or horticultural oil.
• Mealybugs: These appear as small, cottony masses on stems and leaves.
  • Control: Dab with rubbing alcohol on a cotton swab, or use insecticidal soap.

Integrated Pest Management (IPM):

The best approach to managing diseases and pests is to use an integrated pest management (IPM) strategy, which emphasizes prevention and the use of least-toxic control methods. This includes:

• Monitoring: Regularly inspect plants for signs of problems.
• Cultural Practices: Provide optimal growing conditions (sunlight, water, soil, etc.).
• Biological Control: Introduce beneficial insects that prey on pests.
• Chemical Control: Use pesticides only as a last resort, and choose the least toxic options.

Using Geraniums in the Landscape and Beyond

Geraniums are versatile plants that can be used in a variety of ways:

• Containers: Zonal, ivy, and scented geraniums are excellent choices for containers. Use a well-draining potting mix and choose a container that is appropriate for the size of the plant.
• Hanging Baskets: Ivy geraniums are particularly well-suited for hanging baskets, where their trailing stems can cascade over the sides.
• Window Boxes: Geraniums add a splash of color to window boxes. Choose varieties that are appropriate for the amount of sunlight the window box receives.
• Garden Beds: Zonal geraniums can be used as bedding plants, providing a mass of color throughout the summer. Hardy geraniums can be used as groundcovers or border plants.
• Edging: Low-growing, compact geranium varieties can be used to edge pathways or flower beds.
• Cut Flowers: Geranium flowers can be used in cut flower arrangements, although they are not as long-lasting as some other flowers.
• Culinary Uses: The leaves of scented geraniums can be used to flavor teas, desserts, and other dishes.
• Aromatherapy: The essential oils of scented geraniums are used in aromatherapy for their calming and uplifting properties. Research at the University of Illinois suggests that rose-scented geranium oil can help reduce anxiety.

Sourcing Quality Geraniums and Related Products

Gardencenterpoint.com understands the importance of starting with healthy, high-quality plants. We’re not a retailer, but your trusted guide to finding the best sources for all your gardening needs. We connect you with reputable nurseries and garden centers that offer a wide selection of geraniums, along with the tools and supplies you need to succeed.

Finding the Best Geraniums:

• Local Nurseries and Garden Centers: These are excellent sources for finding healthy, locally adapted geraniums. You can often get personalized advice from knowledgeable staff. Gardencenterpoint.com provides a directory of reputable nurseries in your area.
• Online Retailers: Many online retailers specialize in plants, including geraniums. Look for retailers with positive reviews and clear shipping policies. Gardencenterpoint.com offers curated lists of trusted online plant sources.
• Consider Plant Size and Health: Look for plants that are well-branched and have healthy green foliage. Avoid plants that are leggy, wilted, or have signs of disease or pests.

Essential Geranium Care Products:

• Potting Mix: Choose a well-draining potting mix specifically formulated for containers or a general-purpose mix amended with perlite and vermiculite.
• Fertilizer: Use a balanced, water-soluble fertilizer or a slow-release fertilizer. Gardencenterpoint.com provides reviews and comparisons of different fertilizer brands.
• Pots and Containers: Select pots and containers that are appropriate for the size of your geraniums and have drainage holes.
• Pruners: Sharp pruners are essential for deadheading and pruning geraniums.
• Watering Can: A watering can with a long spout is helpful for watering geraniums at the base of the plant.
• Pest Control Products: If needed, choose insecticidal soap, neem oil, or horticultural oil for pest control. Gardencenterpoint.com offers guidance on choosing eco-friendly pest control options.
• Gardening Gloves:Protect your hands.
• Trowel: For planting and transplanting.

Gardencenterpoint.com provides comprehensive reviews and buying guides for all these products, helping you make informed decisions. We also link to reputable retailers where you can purchase these items. We aim to be your one-stop resource for all things gardening. We don’t sell the products ourselves, but we show you where to find the best deals and highest quality.

Troubleshooting Common Geranium Problems

Even with the best care, geraniums can sometimes experience problems. Here are some common issues and their solutions:

• Yellowing Leaves: This can be caused by overwatering, underwatering, nutrient deficiency, or root rot. Check the soil moisture, adjust your watering schedule, and fertilize if needed.
• Leggy Growth: This is usually caused by insufficient light. Move the plant to a sunnier location or prune it back to encourage bushier growth.
• No Flowers: This can be caused by insufficient light, lack of fertilizer, or improper deadheading. Ensure the plant is getting enough sun, fertilize regularly, and remove spent flowers.
• Dropping Leaves: Sudden leaf drop can occur due to extreme temperature changes, overwatering, or underwatering.
• Brown Leaf Edges: This may indicate underwatering, low humidity, or fertilizer burn.

When to Seek Expert Advice:

If you are unable to diagnose or solve a geranium problem, don’t hesitate to seek expert advice. Gardencenterpoint.com can connect you with local horticultural experts or Master Gardeners who can provide assistance.