Nov
10
2010

How do you overwinter geraniums?

Geraniums (Pelargoniums) - courtesy di_the_huntress - CC-BY

There are a few good ways to overwinter geraniums even where the weather is coldest.

1 – Geraniums (Pelargoniums and true geraniums alike) are expensive.  A large display of geraniums generally means some real money has been spent on gardening.  And sadly, most people re-buy every spring.

2 – Geraniums are ridiculously easy to overwinter.  I have used the following methods with good success.   These techniques also work well on the tender, scented leaf geraniums from the herb garden.

With the rainbow of flower and leaf colors and even scents, it is difficult to watch beautiful and expensive geraniums die from a hard frost or deep freeze (which in my area has been known to happen before the first ‘real’ frost warning is given.) There are several ways to keep geraniums through the winter for a head start on blooms next spring and a big savings to your garden budget.

Method one is to simply keep them growing in containers.  If you have good lighting (geraniums like at least 4 – 6 hours of direct sun each day) Geraniums grow well indoors in containers with proper care and other environmental conditions. Before the first frost, cut back plants to half of their original size and then inspect them for insects or disease. Then, dig the healthy plants and transplant into pots. Please use potting mix made for containerized plants instead of garden soil. Garden soil is often heavy, compacted, and may contain insect eggs and larvae which may damage plants.  Place the potted plants in a cool location with plenty of bright, direct sunlight. Water plants well after potting and as needed when the soil begins to dry. Growth tips may need pinching once or twice during the winter to promote branching and prevent ‘leggy’ growth. Before planting outside in May, feed lightly. Plants kept in containers over the winter are usually larger than most geraniums sold in the nursery. This allows you to have a head start on growth which means your plants may reach “specimen” size and bloom much sooner.  I have a red zonal geranium, four years old and repotted once.  It is the only one I actually overwinter in the pot.  By the beginning of August, it is a specimen size plant as large as any I have ever seen in California or other warm area where they grow outside year round.  I don’t ‘replant’ it outside in May, instead I sink the whole pot into the ground and cover the rim with mulch.  Nobody has to know it’s always potted, they just wonder how I get such large geranium plants in Ohio.

The next method (and the one I use most frequently because of space considerations) is “brown bagging” them.  Once again, check your garden Geraniums for disease and insects.  Dig the healthy plants, shake the soil from their roots and dump ‘em into open brown paper bags and put the bags in a cool, dark and dry place.  I also just hang the plants upside down (without bags) in an unused closet. Ideally the temperature should be between 45-50 F. ( For information about temperature conversion between Celsius and Fahrenheit, read degrees Fahrenheit.)  Once a month, take the plants out of the bag or off the hook and put in a sink full of warmish water for an hour or two.  Most of the leaves will fall but as long as the stems stay hard, the plant is alive.

Pot up dormant ‘brown bagged’ geraniums in containers in late March or early April.  Then water thoroughly, cut back the dead stem tips and place potted plants in the brightest area you have to start new growth. It sometimes takes several weeks for plants to begin growing after brown bag storage, which is why early April at the latest.

Another method is “in pot dormant storage” which is good if you want to overwinter some full size geraniums.  First, pot up your geranium and let the soil dry out and cut the plant back by about half.  Then cover each plant with an overturned paper bag and store in a cool dry location.  Check them monthly to see if

they are shriveled, spray the plant and lightly water the root area.  In both ‘in pot’ and ‘brown bag’ dormant storage, when you spray or water the plant, allow it to dry off before returning to its paper bag.

Geraniums are so easy to overwinter, and even though many people believe they are ‘over planted,’ a respectable display of geraniums in your garden provides an ‘expensive’ look that is the real cause of much of other people’s jealousy.

So, be classy.  Grow a garden full of geraniums.

For more information about growing geraniums.

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