Ottawa Horticultural Society

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Growing Geraniums Under Lights From Seed

Newsletter Winter 2000 page 4

By: Mary Sinclair and Pat Russell Back to the web version We have been growing geraniums from seed under lights for many years and can boast a one hundred percent germination rate every year. We dont know what the secret step in the process is, but we share with you our method and hope that you, too, will have the same success.

Order early if you want to try a much promoted new variety.

Sow seeds by the beginning of March for July blooming. They can be sown earlier for earlier blooming, but our timing results in vigorous growth and fresh blooms right into fall.

Step 1 Soak seeds for 24 hours. Dampen several layers of paper towel and lay the seeds on one half making sure they are spread out sufficiently for them not to touch each other. Fold the layers over on the seeds, and place them on a plastic seed tray or any container that can be covered with a plastic lid. Plastic take-out containers are ideal. The lid ensures that the paper towel is not going to dry out, although you should check once or twice to make sure. After 24 hours, the seeds should have started to germinate.
Step 2 Prepare containers for planting. Plastic inserts, 21/2 x 21/2 inches, which fit into the white plastic seed trays work well, and can be used over several years if handled carefully. Use the soilless mix called Pro-mix BX and mix it thoroughly with hot water ahead of time. It should be damp but not wet, and hold together with no excess moisture when squeezed. At time of sewing the mixture should have cooled. Fill the containers, making sure that there are no air pockets, especially at the corners. With a pencil, make a quarter inch impression in each container and drop one seed in each. (Be careful not to damage the new shoot when you remove the seeds from the paper towel. Tweezers are useful.) Cover with soil and tamp gently.
Step 3 Place a plastic cover over the tray and put it on a source of heat. An old electric mattress pad, set at high and covered with a plastic sheet, is ideal. The soil temperature should be around 24 degrees C. Place the tray under lights at a distance of no more than six inches.
Check the growth daily as the new growth can appear almost immediately. As soon as most of the seeds have germinated, in 4 to 5 days, remove the plastic cover and reduce the heat.
Step 4 Ongoing growth. Make sure the soil doesnt dry out. If the mix was wetted sufficiently at first, no extra watering should be necessary until the growth accelerates and the true leaves have developed. When this happens, remove from bottom heat, give a light fertilising with 20-20-20 and repeat about every second week. Always water from the bottom. Keep the lights about six inches from the seedlings to prevent them from becoming leggy, and give them sixteen hours of light a day.
Step 5 Continue to grow the plants in the original containers until it is warm enough to plant them outside in planters or in the garden. If you wish, they can be transferred to 41/2 inch plastic pots as an interim step before planting outside and, as long as you give a light fertilising every second or third week, they can be potted up into more soilless mix.

Happy planting and enjoy lots of healthy, colourful geraniums this summer and for many years to come!!
- Mary Sinclair and Pat Russell

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