Bring Geraniums Inside When It Gets Cold Outside

Q: Can one leave geranium plants in the yard all winter? If so, how do I treat them?

A: Geraniums come from tropical climes. You could leave them out for the winter if you lived in Los Angeles. But they blacken and die immediately when we get hard freezes, even though they can handle weather down into the 40s.

If you want to protect the plant for re-growth next spring, you can bring it inside and keep it as a houseplant if you have room. Dig it before we have a hard freeze and prune back the top by about half. Place plants in a cool, well-lighted room. During winter you'll be unlikely to get any bloom.

Or store them: Lift the plant and prune back about half the top growth. Plant in a pot just big enough for the roots. Store pots on their sides in boxes. Place a couple of inches of slightly moist peat moss or sawdust in the bottom of the box to hold the pots, then cover them with more moist sawdust.

The object is not to have the plants grow, but to store them dormant. An unheated garage where the temperatures don't freeze would be ideal. Don't water; just check once a month to see that the covering material doesn't dry out totally.

In spring, when the light's stronger, bring the plants out into the light, repot and cut off all dead foliage. Your plants will leaf out and flower again.

Or you can take strong 4-inch cuttings, root them now and pot up the little plants, keeping them as houseplants over the winter. These choices depend on how much room you have indoors for playing with geraniums.

Many gardeners, looking at all these options, leave the growing to nurseries and buy fresh plants each spring.

Q: I have containers on my deck with plants like impatiens and daisies. Which ones will winter over and do they need special care?

A: Many of the plants we grow as annuals in the Northwest are perennial in parts of the country with frost-free winters. Which ones survive here depend upon their relative cold-hardiness and what kind of winter we get.

It is not uncommon for Marguerite daisies, petunias, sweet Williams and other summer flowers to make it through a mild winter, particularly if they get some protection.

Place containers close to the house where they will get shelter from the wind and, perhaps, a bit of radiated heat.

Plant roots are always more sensitive to cold than leaves and stems. Plants in containers are at special risk, since the roots don't have the insulation of a large mass of soil.

Anything you can do to insulate your pots, boxes and baskets will help. Dry fall leaves in plastic garbage bags work well. Fill the bags about half-way only, so you can shape them around your containers.

Apartment dwellers can do the same with styrofoam shipping "peanuts" or even wadded-up sheets of newspaper.

As a finishing touch, you may want to drape some floating rowcover material over the tops of the container. It is light and "breathes," so it can be left on all winter.

You can use an old sheet or blanket or a piece of plastic. Any of these materials should be put on when night temperatures are expected to drop below 30 degrees F. and removed the next morning.

Gardening runs Friday in Scene and Sunday in Home/Real Estate. It is prepared by Mary Robson, Master Gardener program director, Holly Kennell, Washington State University/King County Cooperative Extension agent, Susan Miller, integrated pest-management specialist, and volunteer Master Gardeners.