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Geraniums: How to Plant, Grow, and Care for Pelargoniums | The Old Farmer's Almanac

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Geraniums

Photo Credit
aniana/Shutterstock
Botanical Name
Pelargonium spp.
Plant Type
Houseplant
Annual Flower
Sun Exposure
Full Sun
Bloom Time
Spring
Summer
Flower Color
Multicolor
Pink
Purple
Red
White
Hardiness Zone
10
11
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How to Plant, Grow, and Care for Geraniums

Catherine Boeckmann
May 22, 2023
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Pelargonium (aka common geraniums) are colorful summer-flowering plants that are popular for hanging baskets, pots, and also garden beds. Drought- and heat-tolerant, these tender annuals can bloom all summer from June through fall frost! See how to grow and care for pelargonium.

Note: Despite being commonly called “geraniums,” pelargoniums are not true geraniums which belong to a separate genus (Geranium) which are cold-hardy perennials. The guide below is about the 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 “geraniums” today were 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.

Their original common name stuck, however, 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 Pelargonium

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 a bedding plant 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 which are sometimes bi-colored with bronze or purple markings. Once mature, most geraniums are 12” to 18” tall and 18” to 24” wide, depending upon cultivar.

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

Read Next

Planting

Pelargonium aka common geranium are sun lovers and require 5 hours of sun per day. They don’t require as much watering as many annuals but they do prefer moist, well-drained 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.

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.

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).

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

In the ground, avoid planting too densely so that the plants have plenty of air circulation. Allowing any geranium variety to have generous root growing space is very important; they will deteriorate without space to grow. 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 you’re 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 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 look like they need to be refreshed.

Geranium

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 getting the new growth to appear, is keeping it. And here’s some help with that:

  • Water only when the leaves show signs of drooping and provide only small amounts. 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.
Recommended Varieties
  • The Common or Zonal Geraniums (Pelargonium x hortorum) thrive in containers (as well as outdoors).
  • Ivy-Leaf Geraniums (Pelargonium peltatum) are very popular for hanging baskets, window-boxes, and containers. 
  • Scented Geraniums bring the scent of roses, lemons, mint, apple, strawberry and other scents into your garden or home! It can be addictive to collect them all. Learn more about scented geraniums.
Harvesting

How to Root 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 newspaper or put it in the shade for 24 hours, so that 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.
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.
  • 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.
Pests/Diseases
  • Diseases and pests are usually not severe in outdoor situation 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. 
Annuals

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Comments

Donna Woodman (not verified)

4 days 14 hours ago

How can I keep the squirrels from digging in my geraniums?

Donna-

Squirrels can be such a pest! Check out this link for ideas to keep the squirrel population at bay: https://www.almanac.com/pest/squirrels

LYNN BROMAN (not verified)

1 week ago

20 gallon pot!!!! That's about the size of garbage can. Even 20 L is large for geranium.

Joyce Klawon (not verified)

2 weeks 6 days ago

I bought a Sunbelt geranium 34 years ago for a pot outside in summer. I trim it back in fall, bring it into the basement where it gets sun all afternoon. It gets enormous over the winter, and blooms. I trim way back in spring, and put it outside, slowly into direct sunlight. I have split it many times, and just finished splitting and repotting it again, plus gave away many large clumps of the geranium to friends. I even gave a large piece to the nursery I bought it from 34 years ago!!

Wow! Awesome! You just inspired me to try to keep mine alive. I have 2 hanging baskets and it breaks my heart to watch them die this winter. Will try to keep them inside this year and see how it goes.

Tim Haut (not verified)

1 month 3 weeks ago

My mother and my grandmother used to pull their geraniums at the end of the summer, knock the dirt off the roots, and hang them upside down in the cellar. They dried out, dead as a doornail, it seemed. But late winter they would pot them up and they would come to life. Have you heard of this?

Hi Tim,

Yes, in addition to digging up geraniums and replanting them in pots, bare-root storage is a common way to store your geraniums during the winter months.

After removing the dirt from the root system, you can either place them in a large paper sack and store in a cool, dry location, or, like your mother and grandmother did, hang the plants upside down in a cool, dry location. The foliage and the shoot tips will eventually die and then in March, you want to prune each plant to remove all shriveled and dead material. What will be left is the to live stem tissue, which can be planted in pots for the remainder of the spring before planting outdoors in May.

Thanks for sharing!

I’ve not only heard of it, I’ve done it. As we speak, I have 3 plants in pouches in my garage ready to clean up and plant after the last frost. I’m hoping for the best.

Linda Landwehr (not verified)

1 month 3 weeks ago

My grandmother lived up stairs in the first house we purchased. She grew geraniums in large pots. One to a pot. The plants were a couple feet tall. She kept them in her northeast kitchen all winter and set them out on the porch roof for summer. She had a door to the roof. They bloomed beautiful all year. I have never seen geraniums that size again.