How to Grow Geraniums (Pelargoniums) Indoors or Outdoors
I’ve always thought of geraniums as an old-fashioned flower. They were ubiquitous during my childhood. It seemed that every stoop had a pot of red geraniums on it. Red is not one of my favorite colors for my garden so I haven’t looked closely at geraniums for years. Then I saw pink bicolor one that stopped me in my tracks. I had to have it. And I started looking more closely at geraniums.
What are Geraniums?
Geraniums are native to South Africa. They were brought to Europe prior to the 17th century. In 1630 John Tradascant the Elder, a renowned horticulturist, brought them, in the form of seeds, to England.
The Geranium family is quite large. What we call geranium here in the US, is known as pelargonium, a subgenus of the geranium family, throughout the rest of the world. We grow two types of geraniums: zonal geraniums which have distinctive variegations or “zones” on their leaves and ivy geraniums which have leaves that look more like ivy and a draping habit. Ivy geraniums are used in containers and hanging baskets. Flower colors for both are red, pink, white and bi-colors.
Geraniums are subtropical perennial plants hardy in zones 9 through 12. In colder growing zones, they are grown as annuals. They can also be over-wintered indoors or grown entirely as houseplants. Outdoors, they can be grown in the garden or in containers.
How to Grow Geraniums Outdoors
In the garden, you should wait to plant your geraniums until after all danger of frost has passed and the soil has warmed. They like slightly acidic, well-drained soil. Give them a good watering after being planted and then water them regularly, allowing the soil to dry out between waterings, for the rest of the growing season.
They need a minimum of 4 hours of sunlight, preferably in the morning, to look their best. In areas with very hot summers, they need shade in the middle of the day. Too little sunlight or too much heat will cause them to stop blooming. Mulching around your plants will keep the soil cool in the summer.
Geraniums need to be fertilized every 4 to 6 weeks. Pinch your plants to encourage them to get bushy and remove all dead flowers to encourage reblooming.
To grow in containers, make sure you purchase a container that is large enough to accommodate the roots of the full grown plant which can reach 2’ in height. Dwarf geraniums usually grow 6” to 8”. The container must have a drainage hole. Water regularly, allowing the soil to dry out between waterings and fertilize with either a slow release fertilizer or a liquid fertilizer applied every 2 to 4 weeks. Your container should be in an area that gets morning sun and afternoon shade. Pinch the foliage to encourage branching and remove dead flowers to encourage reblooming.
How to Overwinter Geraniums Indoors
Geraniums can be overwintered in your home. Either bring the entire container indoors in the fall and place it in a sunny window or if you are growing geraniums in your garden, carefully dig up the plant, place in a container that is large enough to accommodate the roots and then prune the plant back to about 6 inches. If you have a basement, you can dig up the plant and literally hang it upside down like you do to dry herbs for the winter. In the spring, take it down, prune the foliage back two thirds and replant in your garden.
Another way to overwinter your plants is to take cuttings and root them indoors during the winter. In the spring you can plant the new plants outdoors after all danger of frost has passed and the soil has warmed.
How to Grow Geraniums Indoors
Geraniums can also be grown indoors as houseplants provided you have a south or west facing window. If you don’t have a sunny window, you can grow your geraniums under lights. Don’t bother with expensive Gro-Lites. Plain old fluorescent lights are just fine. Use 40 watt bulbs that are 12 inches above your plants and keep them on for 16 hours a day. A timer that can turn your lights on and off is helpful.
Just like plants grown outdoors in containers, you will need to water your indoor plants regularly allowing the top inch of soil to dry out between waterings. Use a slow release fertilizer or fertilize every two to four weeks. Keep your plants warm by keeping them away from drafts such as by an outside door. Cold will kill them.
Deadhead the flowers to encourage more blooms and pinch the foliage to encourage branching.
How to Grow Geraniums From Cuttings
Geraniums can be propagated by both seeds and cuttings. Cuttings should be done in the late summer. Use stem cuttings and rooting hormone for best results. A stem cutting is a cutting that is taken from the main stem or branch of your plant. Make a 4 inch cutting from any the top stems of your plant. Those are the parts of the plant that are actively growing and will grow roots the easiest. Remove the leaves from the bottom third of the cutting. Dip the cut part of the stem in rooting hormone and then gently press the cutting into a container with pre-moistened soil up to the level of the first set of leaves. Place the container under lights or in a sunny window. Roots should begin to grow within 5 weeks. You will know that roots have grown because there will be new leaves on your cutting. Plants without roots cannot grow new leaves.
At this point, you can keep your new plant as a houseplant or overwinter it until the following spring when you can plant it outdoors in your garden or in a container.
How to Grow Geraniums From Seed
You can also start geraniums from seed. Start your seeds 8 to 10 weeks before your last frost date. Scarify them before planting. Scarification is done by either gently sanding the seed coat or knicking it with a sharp knife. The idea is to open the seed coat so that moisture can get in and start the germination process.
Be patient. Geraniums are perennials and therefore the seeds take longer to germinate. It could be up to 2 weeks before you see any signs of life. Keep your seeds and resulting seedlings warm (a heat mat is helpful) and moist. You can plant seedlings outdoors in your garden or in a container after all danger of frost has passed and the soil has warmed. You can expect flowers in about a month.
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© 2015 Caren White