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Planting and Growing Geraniums (Pelargoniums)

Pink Pelargonium flowers
Image Credit:
aniana/Shutterstock
Botanical Name
Pelargonium spp.
Grown as
Tender Perennial
USDA Zones
9a
9b
10a
10b
11a
11b
Toxicity
Toxic to Dogs and Cats
Sun Exposure
Full Sun
Water Needs
Low
Height
1–3 feet
Spread
Under 1 foot
Soil pH
Acidic
Neutral
Bloom Time
Spring
Summer
Flower Color
Multicolor
Pink
Purple
Red
White
Special Features
Container-Friendly
Cut Flower
Fragrant
Long Blooming
Low Maintenance
Attracts Butterflies
Attracts Hummingbirds
Attracts Pollinators
Deer-resistant
Rabbit-resistant
Resilience
Drought-Tolerant
Heat-Tolerant
Salt Tolerant
Plant Type
Flowers
Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Confused by the whole “geranium vs. pelargonium” thing? You’re not alone! While your plant tag may say “geranium,” chances are it’s a pelargonium—a colorful, sun-loving superstar that blooms nonstop from summer till frost. These beauties aren’t just pretty faces either—they’re tough, drought-tolerant, and perfect for pots, beds, and hanging baskets. We’ll show you how to grow and care for these cheerful charmers like a true garden pro.

Note: Despite being commonly called “geraniums,” pelargoniums are not true geraniums that belong to a separate genus (Geranium) which are cold-hardy perennials. The guide below is about growing the “common geranium” (genus Pelargonium), which is the tender annual most of us know and love.

Geranium or Pelargonium? A Case of Mistaken Identity

The popular plant that most of us call “geranium” today was introduced to Europe by Dutch traders who brought them from South Africa in the early 18th century. Because these new plants resembled the hardy wild geraniums already growing in Europe, botanists mistakenly grouped them together into the same genus.

In 1753, Swedish botanist Carl Linnaeus classified them under the genus Geranium. When it was later discovered that these new “geraniums” differed from European geraniums in the shape of their petals, the number of stamens, and other factors, they were reclassified under Pelargonium, meaning “stork’s bill”—a reference to the long, sharply pointed shape of their seedpod.

However, their original common name stuck, and we still say “geranium” when we actually mean “pelargonium.” Perhaps it’s just hard to say pelargonium! This word is pronounced “Pel-ar-GO-knee-um.”

About Pelargoniums

Pelargonium, aka common geraniums, are small- to medium-sized herbaceous annuals in North America. Because they can bloom so nicely all summer (through frost), these flowering plants are often used in planters and window boxes, but they’re also used as bedding plants along foundations, paths, and entrances.

The common geranium comes in a wide range of floral colors (red, orange, pink, white) in single or double flowers set high above lush, green leaves, sometimes bi-colored with bronze or purple markings. Once mature, most geraniums are 12 to 18 inches tall and 18 to 24 inches wide, depending upon the cultivar.

Many cultivars, such as ivy-leaved pelargoniums, are trailing types that look wonderful in hanging baskets. There are also scented geraniums that are aromatic when the leaves are rubbed! Then, there are upright pelargoniums which are bushy with attractive foliage which look great in bedding displays. 

Planting

When to Plant Pelargonium

As sun-lovers, pelargonium should not be put outside until nighttime temperatures are regularly above 55°F (13°C). Then, in late summer, when nighttime temperatures start to dip under this temperature, bring them inside.

Where to Plant Geraniums

Pelargonium, aka common geranium, is a sun lover. It requires 5 hours of sun per day. It doesn’t require as much watering as many annuals, but it does prefer moist, well-draining soil. 

Often grown in pots or as container plants, they can be kept outside until fall frost dates in a partly sunny to sunny location. This annual will die with several frosts or the first hard freeze.

How to Plant Pelargonium

When buying geraniums from the garden store, pay close attention to color and size. Healthy leaves will have no discoloration on or below them, and the stems will be sturdy, not straggly. Be sure to avoid any plants with obvious signs of pests as well. 

Place plants in large pots with drainage holes to avoid root rot. To allow for root spread, plant one plant (possibly two plants) in a large pot (at least 12” in diameter).

When planting in containers, use an excellent, well-draining potting mixture (not heavy soil). Geraniums do not like to sit in soggy or compacted soil.

Avoid planting too densely in the ground so the plants have plenty of air circulation. Allowing any geranium variety to have generous root growing space is very important; they will deteriorate without growing space. Also, to avoid pests, practice crop rotation and do not keep planting pelargonium in the same place every year. 

Growing

How to Care for Geraniums

  • If planting in the ground, add a light mulch to cover the soil to cool the root zone.
  • Allow soil to dry to some extent between waterings, then water thoroughly. Over-moist soil does more damage than under-watering. Do the finger poke; if it’s dry at 1-inch depth, then water. Do not water from overhead nor splash the foliage when watering, or you’ll invite disease.
  • Deadheading is important for continuous bloom throughout the summer. Deadhead all spent blooms. Also, deadhead after a heavy bloom or a strong rain. One reader shared a tip, “For continued reblooming, finger pinch just below the spent flower as much as possible. I did, and each of my pelargoniums bloomed from spring into fall year after year.
  • To promote bushiness and curtail legginess, pinch back the stems.
  • During active growing months, fertilize every 2 weeks or so. Use a water-soluble fertilizer at half-strength. Don’t fertilize in winter, when the plant should be dormant.
  • If you’re bringing in the plant for winter, water much less, but do not let the roots dry out entirely. Geraniums do best when given a period of dormancy through the winter months, during which they use less water and do not grow much. See below for more overwintering instructions.
  • Geraniums can be repotted in spring to encourage new growth—or, if they need to be refreshed.

red and white Geranium flowers

Overwintering Geraniums

  • Geraniums that have spent the summer outdoors can be kept as houseplants, provided they get lots of sun. In northern climes, the sun may not be strong enough in late winter to stimulate buds on some varieties.
  • Before the first fall frost, lift the plants and, using a sharp, clean knife, cut the stems back in a shapely fashion to about 6 to 8 inches. They should not have to support great masses of leaves in the low-sunlight environment they are about to enter. Save a few stems as cuttings to root—an easy way to multiply your plants.
  • Transplant the “mother plant” to the smallest pot possible—enough to just fit the roots—using regular potting soil to fill.
  • Keep the plants in the shade for a week, then place them in a sunny spot (they need all the sun they can get) and keep them cool.
  • During winter, geraniums grow best with night temperatures of 50° to 60°F (10° to 16°C) but will survive if they drop to 32°F (0°C) and/or rise above 80°F (27°C), as long as they are kept relatively dry.
  • When new growth appears in the spring, cut off all the old leaves.

The only thing more difficult than achieving new growth is keeping it. And here’s some help with that:

  • Water is only available when the leaves show signs of drooping, and only small amounts are provided. Do not fertilize or feed the plants. It is critical that these plants get rest.
  • If you want your overwintered geraniums to bloom for Memorial Day, pinch them back in February. Once warm weather returns and all danger of frost has passed, take the plants outdoors and transplant them to beds or pots, as you wish.

Harvesting

How to Root Geranium Stem Cuttings

Most geraniums root VERY easily from stem cuttings in soil, coarse sand, water, perlite, or other rooting material.

  1. Using a sharp, clean knife, make a slanted cut 4 inches below a stem tip, above a node where leaves emerge. Trim the cutting to just below a node. Remove any buds, all but two or three leaves, and the leaflike stipules at the base of leaf stalks.
  2. Roll the stem cutting in a newspaper or put it in the shade for 24 hours so the cut end will seal and not rot.
  3. Push the stem into a pot of moistened rooting medium and store it in a warm, shady place for 2 days. After that, give the cutting some indirect sun. Moisten the medium only as needed.

Pests and Problems

  • Diseases and pests are usually not severe in outdoor situations but it can happen if you continually splash water on the foliage or there are rainy periods which can affect mass plantings.
  • In hot weather, you may see brown leaf tips. Yellow leaves mean you are over- or under-watering.
  • Indoors, common houseplant pests include mealybugs, whiteflies, and spider mites. 

Types

  • Interspecific: zonal and ivy hybrids; nonstop flower producers
  • Ivy (Pelargonium peltatum): named for a trailing habit and ivy-like foliage; single, semidouble, or double flowers; colors include bicolor, burgundy, pink, purple, red, salmon, and white. Very popular for hanging baskets, window boxes, and containers.
  • Regal, aka ‘Martha Washington’ (P. x domesticum): bicolor burgundy, lavender, pink, and white blooms; fussy—prefers cool, wet, climate conditions to hot, humid, and/or sunny; inappropriate conditions will reduce flower production; often a houseplant
  • Scented: foliage yields scent (cedar, lemon, lime, mint, orange, and rose) when brushed or rubbed; note that ‘Citronella’ does not repel mosquitoes; pink or white flowers are smaller than those of zonals. It can be addictive to collect them all. Learn more about scented geraniums.
  • Seed: similar to zonals; propagated by seeds; slower-growing, shorter, more compact than zonals; smaller but more numerous flowers than zonals; flowers “shatter” (are shed naturally)
  • Variegated: a form of zonal; bi- or tricolor foliage; tends to have fewer flowers than other zonal types
  • Zonal (P. x hortorum): the most common form; “zonal” refers to patterns on the leaves that darken with maturity; propagated by cuttings; single or double flowers; colors include bicolor, orange, purple, red, salmon, and white. These thrive in containers (as well as outdoors).

Wit and Wisdom

  • For minor cuts, apply crushed geranium leaves to stop the bleeding.
  • In the language of flowers, scarlet geranium means silliness. Find out more flower meanings here.
  • Geraniums are known to be toxic to Japanese beetles, so you won’t have to worry about those pesky pests. As companion plants to cabbages, corn, peppers, roses, and tomatoes, pelargoniums repel cabbage worms and Japanese beetles.
  • Geraniums may cause indigestion or vomiting in young children and pets (cats, dogs), so keep the plants out of reach of curious pets and children.
  • “Pelargonium” derives from the ancient Greek word pelargos for stork, while “Geranium” comes from the Greek word geranos, for crane; the fruit of both resemble a bird’s beak.

Flowers

About The Author

Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana.

Read more from Catherine Boeckmann

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Comments

<span>Ann Grassel</span> Thu, 09/11/2014 - 23:46
I have 2 geraniums here in Walnut Creek, CA. I have huge plants with little or now flowers in pots in my sunroom. They get plenty of sun and I have been using a 10-52-10 fertilizer. What can I do to get it to bloom and how often should I fertilize? Thanks
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 09/12/2014 - 09:42

In terms of sunlight, is it really bright and direct at least four hours a day? In terms of fertilizer, use a more balanced fertilizer: 15-15-15 or 20-20-20. Finally, you could always repot with new potting soil mixture. Before you do, hold back the watering for 6 to 8 weeks until it's not quite dry and cut it back. After repotting, start watering again, fully moistening the soil, and then allow the top half-inch of soil to dry before watering again. Also, we would try summering your geraniums outdoors if you can.

 

 <span>Ruth Davis</span> Fri, 09/05/2014 - 11:16
I found small green worms eating the blooms on my plants. They are eating only the blooms. What are they and what do I need to do get get rid of them before bringing them inside
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 09/08/2014 - 11:26

Hi, Ruth, Allow us to introduce you to the geranium budworm, aka tobacco budworm. At maturity, these are moths that lay a single egg at night on the geranium buds. The larvae color may be red or green. These turn into caterpillars that drop into the soil and pupate. As the days grow shorter and seasons transition, the insects "hibernates" in the soil, staying for the winter.

Handpicking is the most common control. Around dusk, look for the worms when you see holes in the leaves or flowers. In daylight they hang around the base of the plant.

If your geraniums are potted, change the soil.

Numerous wasps, bugs  (e.g., Polistes spp. wasps, bigeye bug, damsel bug, minute pirate bugs), and spiders are natural enemies.

We hope this helps.

 <span>Sheila Barrett</span> Sun, 01/26/2014 - 06:33
I've had geranium plants inside in winter and outside in summer for 3 years now and they have done beautifully until now. I've repotted them in the Fall and in the Spring. I have them in a sunny window. They are no longer flowering and they were sooo beautiful for the past 3 winters. I have always rooted cuttings successfully also but this year none are rooting. I'm baffled. Is it because of age? Any advice would be appreciated. Sheila
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 01/27/2014 - 15:45

In northern climates, we tend to store our geraniums in the basement, then repot and bring into a sunny window in February; grow lights help, too.
You've had quite the green thumb. Three years of continuous bloom is impressive. We don't know where you live. Has the sunlight been especially low this winter? Geraniums need strong, bright light, but not direct sunlight. You could always add supplemental lighting. Once the plants photosynthesize more, they should bloom again. You can always repot as well.