Geraniums

Q. I have some geraniums that have been growing in my basement under grow lights all winter. I live in Chicago...I think it's zone 4 or 5...do I need to cut them back...(they are blooming and have been blooming all winter)...or can I just plant them outside...and how much sun can they take when they come from grow lights to the sun? Last year I brought them up and covered them with sheets (made a tent-like area) and each day gave them more sun, but it was work!

A. Geraniums which have been grown indoors under lights or in a window over the winter need to be acclimated to the outdoors. This can be done by placing them in a shaded area during the day and bringing back inside the house at night. Repeat this for about one week. They will not go into shock this way.

Your plastic idea is sound and is work, but so is bringing them inside where the night temps are not below 50 F. If you can place them in the shade and up against the house so it is warmer, then you could leave them outside all the time for conditioning if the nights do not go below 50 F.

Please trim off any tall and leggy stems and it is best to remove the weak flower stems too, as this will bring them into strong flowering sooner.

Then, as they harden, you can slowly move them out where they get 1/2 day sun and then full-day eventually. The more sun and plenty of water and fertilizer, the more they will bloom, if you keep the old flowers cut off.

Member Sue writes~
I have several nice geraniums that I would like to save to replant outdoors next spring. I was going to try to repot them all into a large tub, and find somewhere in the house to keep them till spring. My grandma said that I should just pull them all up, shake the soil from the roots, put in an onion bag, and store in the basement until spring. She said that they will dry up, but perk right back up when they are replanted in the spring. Is this true, or was Granny confusing geraniums with something else? These are not seed geraniums. I don't know what zone this is (except the twilight zone some days), but I live in Omaha, NE.

A. I do not know what you mean by seed geraniums. It sounds to me that you have the garden varieties which bloom from spring to early fall, when they slow and begin to wither and then die from frost. Her advice is sound although there is another overwintering method which you may consider. This is to trim branches back to 6-8", keep the plants in one or more pots full of soil and place in the coolest room you have inside. Water only every 3-4 weeks just to keep alive, no food, and let them vegetate until spring arrives once more.

At that time, replant into the garden beds, trim out any weak growth and start a regular watering and feeding program. You may also take 4-6" cuttings in the spring and root in a vermiculite and perlite mixture.

Q. I hate to toss my beautiful plants away after frost. Can I preserve my geraniums inside until next year? How?

A. Geranium plants can be overwintered in several ways. Before frost, whole plants can be taken from the garden, tied in bundles, and hung upside down in a cool moist area such as a basement for the winter. The humidity should be at least 80% [will not work if you have a dehumidifier] and the temperature should be 35 and 45 F [so it cannot be heated]. Cut back to about 1/3 of their height then plant outside in May, or pot indoors in late winter for early bud break. Give a dilute fertilizer as you see green.

You can also dig the plants and overwinter them indoors in a sunny window. Remove as much of the root system as possible with the tops. Place the plant in a pot large enough to accommodate the root system and cut the plant back to 6" in height. They will need as strong as light as you can provide. Artificial lamps aid very well. Do not forget to feed them monthly, keep yellow and brown leaves cut off, and do not overwater or they may rot.

Geraniums also can be overwintered from cuttings taken in late summer or early fall. Do the same process as above.

Rose writes~
How do I raise geraniums from seed? I got a really nice geranium as a gift. I saved seed from it but don't know how deep to plant the seed, what time of year to plant, etc. Geraniums are one of my favorites, please help.

A. Geraniums have been a popular bedding plant for many years, traditionally grown from cuttings. In recent years, however, seed-grown hybrid geraniums have become popular. The popularity of seed-grown geraniums has increased because they often outperform the older geranium varieties propagated from cuttings. The new seed-grown hybrid geraniums possess excellent vigor, heat tolerance, disease resistance, and are free-blooming. Geraniums are easy to grow from seed. However, they are rather slow growing. Sow seed in mid-to late January to produce flowering plants for spring. Flowering occurs approximately 12-16 weeks after sowing. Generally, the only characteristic that varies within seed is flower color. A commercially prepared medium such as Jiffy Mix is good for germination. Gardeners can prepare their own medium by mixing equal parts sphagnum peat and vermiculite. During germination, damping-off of geranium seedlings can be a serious problem and is caused by various types of fungi that attack the seedlings and destroy them. To discourage damping-off, containers used for starting seed should be clean and have adequate drainage. Previously used containers should be washed in soapy water, then disinfected by dipping in a solution containing one part chlorine bleach and nine parts water. Fill the container with the germination medium to within 1/2-1" of the top. Firm the medium lightly, water thoroughly, and allow it to drain for several hours. Sow the seed in rows 2-3" apart and cover with about 1/8" medium. After sowing, thoroughly water the medium by partially submersing the container in water. When the surface becomes wet, remove the container from the water and allow it to drain. To insure a uniform moisture level during the germination period, cover the container with clear plastic. Set the container in bright light, but out of direct sunlight. Extremely high temperatures may develop if the covered container is set in direct sunlight. These high temperatures may adversely affect seed germination. The temperature of the medium during germination should be 75F. With favorable temperature and moisture levels, the seed may start to germinate in 5-7 days. However, some seed may not come up for 3-4 weeks. Remove the plastic covering as soon as germination occurs. Transplant seedlings into individual containers when the first true set of leaves appears. Handle the small seedlings by their leaves since the small, thin stems break easily. Insert seedlings to the base of the seed leaves, called cotyledons, when transplanting. An excellent growing medium for geraniums consists of one part soil, two parts peat, and two parts perlite. The soil mix should be pasteurized before use. To pasteurize a soil mix, lightly moisten the material, place in a shallow baking pan, and bake in the oven at 180F for 30 minutes. Cool the soil mixture before using. For best results, grow seedlings under fluorescent lights. The lights should be no more than 4-6" above the growing plants. Leave the lights on 12-16 hours per day. If supplemental lighting is unavailable, place the plants in a sunny south window. Geraniums become tall and spindly when grown without sufficient light. Pinch out the shoot tips of spindly plants to encourage branching. Ideal growing temperatures for geraniums are 70-75F during the day and 60-65F at night. Thoroughly water geraniums when the soil surface is dry to the touch. Fertilize weekly with a one-quarter strength houseplant fertilizer. Harden or condition the plants outdoors for 7-10 days before planting into the garden. Plant geraniums outdoors when the danger of frost has passed. Geraniums can be planted outdoors in early May in southern Iowa, mid-May in central and northern portions of the state.

This article originally appeared in the January 13, 1995 issue.

Prepared by Richard Jauron, Department of Horticulture Iowa State University, Ames, Iowa.

Judy writes~
Is there a way to keep geraniums over the winter by hanging them (dry root) in a garage?

A. Yes, read on, as there are several methods of handling geraniums over winter. One way is to take cuttings and root them early in the fall. Stem cuttings, often called "slips," should be about 4" long. Take the slips from the tips of the healthiest stems. Remove the leaves on the bottom 2" of the cuttings. Stick the cuttings in a coarse sand, perlite, vermiculite or a well drained potting soil. Cuttings root faster if the ends are dipped in rooting hormone powder. Stick the cuttings 2" deep in the medium and water thoroughly. Place in a north or east window or underneath artificial lights until rooted. This generally takes 3-4 weeks. After the cuttings have rooted, plant them in individual pots and put them in a well-lighted spot. Keep the soil evenly moist and fertilize lightly every 4-6 weeks once new growth appears. Rather than take cuttings, some people prefer to pot their best plants and bring them indoors for winter. Cut the plant back to about 1/3 its original height. Carefully dig up the plant, and pot it into a 6" or larger flower pot. Water thoroughly and put it by a sunny window. An old method of carrying geraniums over winter is to dig the plants, shake excess soil from their roots, then hang them from your basement rafters. Most basements are too warm and dry now, however, some people report success with this method. To find out if this will work in your basement, try it with several plants, but be sure you take cuttings, too, in case you lose the original plant. Take the plants down occasionally and place the roots in water for 3-4 hours. Then hang them back up. Do this several times over the winter to prevent them from drying out completely. Pot your geraniums in early spring, and put them in a sunny window until frost danger has passed. Assistance: Univ. of MN Extension Service