蜜桃恋人

How to Grow Geraniums: The Complete Geranium Flower Guide

Pink Pelargonium flowers
Photo Credit
aniana/Shutterstock
Botanical Name
Pelargonium spp.
Plant Type
Flower
Sun Exposure
Full Sun
Bloom Time
Spring
Summer
Flower Color
Multicolor
Pink
Purple
Red
White
Hardiness Zone
10
11

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Planting, Growing, and Caring for Geraniums

Catherine Boeckmann

Pelargonium (aka common geraniums) are colorful summer-flowering plants popular for hanging baskets, pots, and 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 鈥済eraniums,鈥 pelargoniums are not true geraniums that belong to a separate genus (Geranium) which are cold-hardy perennials. The guide below is about growing the 鈥渃ommon geranium鈥 (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 鈥済eraniums鈥 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 鈥済eraniums鈥 differed from European geraniums in the shape of their petals, the number of stamens, and other factors, they were reclassified under Pelargonium, meaning 鈥渟tork鈥檚 bill鈥濃攁 reference to the long, sharply pointed shape of their seedpod.

However, their original common name stuck, and we still say 鈥済eranium鈥 when we actually mean 鈥減elargonium.鈥 Perhaps it’s just hard to say pelargonium! This word is pronounced 鈥淧el-ar-GO-办苍别别-耻尘.鈥

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鈥 to 18鈥 tall and 18鈥 to 24鈥 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. 

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Planting

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-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掳F (13掳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鈥 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鈥檚 dry at 1-inch depth, then water. Do not water from overhead nor splash the foliage when watering, or you鈥檒l 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, 鈥淔or 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鈥檛 fertilize in winter, when the plant should be dormant.
  • If you鈥檙e 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鈥攐r, 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鈥攁n easy way to multiply your plants.
  • Transplant the 鈥渕other plant鈥 to the smallest pot possible鈥攅nough to just fit the roots鈥攗sing 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掳 to 60掳F (10掳 to 16掳C) but will survive if they drop to 32掳F (0掳C) and/or rise above 80掳F (27掳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鈥檚 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.

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 鈥楳artha Washington鈥 (P. x domesticum): bicolor burgundy, lavender, pink, and white blooms; fussy鈥攑refers 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 鈥楥itronella鈥 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 鈥渟hatter鈥 (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; 鈥渮onal鈥 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).

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.
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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.
  • 鈥淧elargonium鈥 derives from the ancient Greek word pelargos for stork, while 鈥淕eranium鈥 comes from the Greek word geranos, for crane; the fruit of both resemble a bird鈥檚 beak.

Pests/Diseases

  • 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. 
Flowers
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it鈥檚 not surprising that she and The Old Farmer鈥檚 蜜桃恋人 found each other. She leads digital content for the 蜜桃恋人 website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann
 

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Comments

Diane Tringola (not verified)

6 years 5 months ago

I am growing a standard geranium for a County Fair submission in mid-july. Up to now I have been pinching off all the flower buds so the plant would get fuller. At what point should I let the flower buds grow in order to get them to bloom in mid-july. The plant is fertilized once every two weeks with a water soluble fertilizer and gets at least 6 hours of Sun a day.

Oh, the pressure! We have no direct experience with this kind of timing and can not find it elsewhere, but we learned the following and pass it on in hope that it helps:

鈥 When any given stem is as tall as you`d like or you wish to encourage branching or new basal shoots, pinch out its growing tip but not the flower bud forming alongside. In this way, you allow the terminal bloom cluster to mature and give pleasure while the removal of the growing tip has set into motion the desired activity below. By the time top blooms fade, new growth will be budding.

鈥 If you want a miniature or dwarf geranium to go all to bloom, try potting in a 5- or 6-inch bulb pan or azalea pot (both types are more shallow than the standard, which is as wide across the top as it is tall). This practice allows the little geranium to develop many branches, and when the roots are sufficiently cramped, there will be a profusion of flowers.

鈥 Give the roots a soaking when the surface soil is approaching dryness. If you wait until there is a slight wilting of the leaves, flower buds on the way will wither and die. But never leave a geranium sitting in water.

鈥 Commercial growers have a variety (it seems) of techniques that seem complicated for home growers but you might glean some secrets by reading about this report from Michigan State: http://flor.hrt.msu.edu/assets/PdfAttachments/7Geranium-and-Zinnia.pdf

Good luck in at the Fair!

michelle miller (not verified)

6 years 6 months ago

Where do you pinch them off at? Every time I start to pinch at the bottom where, it seems stem is coming out, doesn't seem to flower as much. Do you just pinch off below the bloom? I love these flowers but can't seem to keep a lot of blooms on them. Thanks!

Hi, Michelle. You only need to pinch 1/4 to 1/2 inch off the end of the stem.

Can you provide more detail on where exactly to pinch geraniums? Or a photo or drawing? I am confused exactly what is meant by 鈥渆nd of the stem鈥. I bought an entire flat of geraniums in April that were covered in gorgeous magenta blooms. Once the original blooms faded, there have no more blooms or even buds. I can鈥檛 figure out why. They have had plenty of sun and water. Thanks!

Marietta McArthur (not verified)

5 years 5 months ago

Do you pinch or do you cut spent flowers

Is there a picture where I can see how to cut the ends off On these flowers because mine look like they鈥檙e dead and I don鈥檛 know how to cut them

I buy full geraniums then they start to get leggy. Do I pinch the plant stems from leaf top 1/4 to 1/2 inch. I break the dying blooms down to where the come off of the stem. My question - where and how do I pinch plant to prevent leggy plant

Bettie (not verified)

6 years 7 months ago

I am planting geranium seeds now and will keep in a green house until May and then want to use them in a wedding in late August. What is the best way to keep small and full of blooms? Zone 5b
Thanks

Did you seed a dwarf variety? These  can be maintained under 8 inches, flower freely, and can be maintained in 4-inch pots. They seem to be more popular in the United Kingdom; you can see mention of them here: http://thepelargoniumregister.com/horticulture-symbols-and-terms/ They might be able to provide some info.

If you are growing standard size, you might need to keep it pruned.