February 11, 2013 - 12:02 pm - Posted in News


A Weekly Column about Plants, Gardens, & Yards

By: Margaret Murphy • ISU Extension Horticulture Educator • Lyon-O’Brien-Osceola-Sioux Counties


Growing Geraniums

What’s better than doing a little planting in the middle of winter? As most garden calendars will remind you, now is the time you can start geranium seeds indoors for beautiful blooms this summer. Geraniums are usually grown from cuttings but seed-grown hybrids have become more popular over the years. These hybrids tend to perform well and possess attractive qualities such as being heat tolerant, disease resistant and free-blooming.

Geraniums are not difficult to start from seed but the seedlings are rather slow growing. It takes about 13-15 weeks after sowing for plants to flower. When you start plants from seed, it’s recommended that you use a soilless mix that is porous and free of insects and disease. Commercial seed-starting mixes are nice because they are sterile, which helps guard against problems such as soil-borne fungi that can cause damping-off. You also want to use a clean container. Types of suitable containers vary widely ranging from peat pots that can be transplanted directly into the garden to containers you can make at home by recycling old milk cartons or yogurt cups. Just make sure that whatever pot you use has drainage holes and, if it has been used before to hold soil, is sterilized. You can use a weak bleach solution made up of 1 part bleach to 9 parts water.

When planting geranium seeds, gently press them into the medium and lightly cover. Keep the medium moist but don’t let it become soggy. To prevent the newly planted seeds from drying out, cover the container with plastic wrap. Geranium seeds do best when the seed-starting medium is kept between 70 and 75 degrees F. So, during germination, place seeds in a warm area but avoid setting the container in direct sunlight as this may “cook” the seeds. You can also place the container on a heat mat to keep the growing medium warm. With proper temperature and moisture, geranium seeds should begin to sprout in 7-10 days.

When seedlings emerge, remove the plastic cover. Seedlings need about 12-16 hours of light each day. If they receive insufficient light, seedlings become tall and spindly or “leggy.” Light can be artificial or natural or a combination of both. Geraniums can be grown under 40-watt florescent tubes – one cool and one warm. Maintain the height of the lights about 4-6 inches above the seedlings as they grow. As plants require a dark period for proper development, don’t forget to turn the light off.

Remember to check the seedlings often to see if they need water. Water when the surface of the growing medium is dry to the touch. Thin the seedlings or transplant them into individual pots when the first true leaves appear. If the growing medium does not contain a fertilizer, you can apply a diluted solution of water-soluble fertilizer (about ½ the recommended rate) once every 2 weeks after the first sprouts appear.

In the spring, after the danger of frost has past and the soil is warm, your geraniums can be transplanted into a flower bed. Geraniums can also be added to hanging baskets, window boxes or left in their own pot for the summer. Before moving the geraniums outdoors, they need to be hardened off. Acclimate them to their new environment by gradually exposing them to direct sun over a 7-10 day period. Start by placing them in a shady area protected from the wind. Bring the seedlings indoors if the forecast calls for cooler temperatures. After the hardening off period is over, keep them in a sunny spot, and, if you keep up with dead-heading, it will not only make the plants look more attractive but will also promote re-flowering.

There are several geranium varieties available that start well from seeds including members of the large-flowered ‘Elite’ Series and the medium-sized and very dependable ‘Orbit’ Series. Varieties in a series will have the same growth habits but may differ in flower color.

To learn more about starting seeds indoors, join me together with several Master Gardeners for a seed starting workshop on February 23rd in Primghar. We’ll be planting some ‘Orbit’ geranium seeds for participants to take home. The cost is $5 and space is limited. Registration information is available online at the Lyon County Extension website (www.extension.iastate.edu/lyon) or call (712) 472-2576. Please feel free to contact me if you have any questions at mmurphy@iastate.edu or through your local County Extension office.  Additional information was provided by ISU Extension and Outreach articles, Growing Geraniums from Seed and Starting garden transplants at home; and Clemson Cooperative Extension article, Starting Seeds Indoors.

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