Geraniums are hardy flowering plants that grow well both indoors and out. The flowers blossom in the late spring and they remain in steady bloom until the first frost of the year. If they are kept indoors, the flowers bloom indefinitely. Grow geraniums indoors on the windowsill to add some color and life to a room or grow them outdoors in clusters or as specimen plants.
Fully Grown Plants
If you have full-grown geranium plants that you were keeping inside, set them outdoors after the last frost date in the area. Temperatures that are too low result in flowers that are small and leaves with a red tinge to them. May is typically a safe time to plant full-grown geranium plants.
Take cuttings from full-grown plants by removing the terminal 3 to 4 inches from the stem, though shorter cuttings are possible as well. Strip off the lower leaves and stick them in sharp sand or perlite. From removing the cutting to the plant developing a root structure that allows it to survive in the ground, the process takes about four weeks. Start this process two weeks before the last frost date in the area and then plant the cuttings in the garden.
Geraniums are hardy growers that grow as well from seeds as they do from cuttings. The only issue with growing geraniums from seed is that there is an extended period of time between sowing and germination. To sow geranium seed in your garden, sow the seed in the worked garden bed in mid to late January. It takes between three and four months for the plants to begin sprouting and flowering after they have been sown.
Geraniums may be started indoors at any time as long as they have enough light. Geraniums need full sunlight in order to thrive. If you are starting your geraniums in the winter, when the days are short, supplement their light with a fluorescent tube light mounted about 1 foot away from the plant. Use clay or plastic pots with drainage holes and dump out the excess water a few minutes after watering.