For spring flowering plants, geranium seeds should be sown in early- to mid-February.
For many years, geraniums have been a common choice for bedding plants. Cuttings are a frequent way to grow plants. Geraniums can, however, also be raised from seeds. Hybrid geraniums that are grown from seeds have great vigor, heat tolerance, disease resistance, and free blooming.
Growing geraniums from seeds is not too difficult. Geranium seedlings, however, develop slowly. For spring flowering plants, geranium seeds should be sown in early- to mid-February. Approximately 13 to 15 weeks after seeding, flowers begin to bloom. Geraniums from the Elite, Orbit, Maverick, and Multibloom Series are recommended for Iowa. A series is a collection of closely related types that share similar traits like height, spread, and flowering behavior. The only trait that typically varies within a series is the color of the flowers.
Jiffy Mix and Redi-earth are two great soilless mixtures that work well as germination media. Geranium seedling damping-off can be a significant issue during germination. Different species of fungi attack the seedlings and kill them, which is what causes damping-off. Containers used to start seeds should be spotless and have sufficient drainage to deter this. Prior to disinfection, previously used containers should be cleaned in soapy water and dipped into a solution of one part chlorine bleach to nine parts water.
The germination media should be poured into the container to within 1/2 to 1 inch of the top. Lightly firm the medium, completely wet it, and then give it some time to drain. Rows of seeds should be 2 to 3 inches apart, and the medium should cover the seeds by about 1/8 inch. After planting, thoroughly hydrate the soil by immersing the container in water only partially. Remove the container from the water after the surface is damp, then let it drain. The media can alternatively be hydrated with a gentle water spray from a sprinkler made of a rubber bulb or a similar tool.
Use clear plastic food wrap or a clear plastic dome to cover the container to maintain a constant moisture level during the germination process. Place the container in a well-lit area away from the sun. If the covered container is placed in the direct sun, there could be an excessive accumulation of heat. When germination is taking place, the medium’s temperature should be between 70 and 75 degrees F. The seeds should start to sprout in seven to ten days at the right temperature and moisture content.
As soon as the seeds start to germinate, remove the plastic covering. Put the seedlings in a window with natural light or under a light fixture. Fluorescent lights should be turned on for 12 to 16 hours a day and placed no higher than 4 to 6 inches above the seedlings. When the seedlings develop their first true set of leaves, transplant them into separate containers using a well-drained commercial potting mix. Handle the little seedlings by their leaves since the fragile, delicate stems are easy to break. When transplanting, place seedlings at the base of the seed leaves (cotyledons).
Grow seedlings under fluorescent lights for the greatest outcomes. One 40-watt cool white and one 40-watt warm white fluorescent tube can be used in a conventional fluorescent shop light. Due to little light, plants grown in windows frequently grow tall and spindly. Geraniums prefer daytime temperatures of 70 to 75 degrees and nighttime temperatures of 60 to 65 degrees. When the soil surface is completely dry to the touch, water the geraniums thoroughly. Fertilization is probably not required if using a potting mix that is sold commercially and has a slow-release fertilizer. For potting mixes without a slow-release fertilizer, applying a diluted fertilizer solution once every two weeks should be adequate.
Before putting the plants in the garden, harden or acclimatize them to the outdoors for seven to 10 days. First, plant the geraniums in a sheltered, shaded area. Then progressively subject the plants to extended sun exposure times. When there is no longer a chance of a frost, plant the geraniums outside. Early May is typically a good time to grow geraniums outside in central Iowa.
When are geranium seeds ready?
For blossoming in late April and early May, sow your geranium seeds in the middle to late month of December. As an alternative, a mid- to late-May sowing should result in flowers. You can plant your seeds in the fall and simply overwinter the young plants to really jumpstart the growing season the following year. If you need some advice, watch our video on how to overwinter geraniums.
It takes geranium seeds 18 to 20 weeks to reach maturity and begin to bloom. This is affected by the season in which the seeds are sown, as well as by temperature and light conditions.
Can I still sow geranium seeds?
Geraniums make a big statement in garden beds and baskets with their vivid red (and occasionally pink, orange, purple, and white) blossoms. In comparison to cutting-propagated variations, seed-grown variants are typically smaller and have more flowers. Additionally, they frequently have greater heat tolerance and illness resistance.
Geraniums are easy to raise from seed. However, it takes persistence to cultivate geraniums from seeds. It may take up to 16 weeks from seed to flower. Knowing when to sow is crucial if you want summer bedding plants since seeds need heat and light to germinate.
Does light help geranium seeds to sprout?
Because geraniums take a while to grow from seed, plant them in mid- to late January. 12 to 16 weeks after seeding, your plants will start blooming.
Because the seeds have hard outer shells, moistening them before planting can aid to boost germination rates.
- Wet a few paper towels. Then, fold the remaining half of the surface over the seeds-covered half. To keep moist, place seeds and wet, folded paper towels in a plastic zip-top bag. The seeds should have begun to sprout after 24 hours.
- Use a commercial growth mix before sowing. Make sure your containers are clean and have drainage holes if you want to prevent fungal illness (damping-off).
- If you’re like me and want to reuse nursery pots that are 2.5 inches in diameter, wash them in soapy water and disinfect them with a rinse that contains a little bleach (one part chlorine bleach to nine parts water).
- Growing medium moistened in a large container. Add just enough water to make the mixture damp enough to act as a sponge, but do not allow it get drenched. Allow to stand for a couple of hours to soak up moisture.
- Growing mix should be piled into each pot to about an inch below the top. Pack loosely, sow two or three seeds per pot, and then cover with a thin layer of growing medium—between 1/8 and 1/4 inch—of growing medium. Water sparingly. (Use a little watering can or spray bottle with a fine rose.)
- Pots should be labeled and placed in a plastic bag with a twist knot. (Or, set the plastic cover in place if you’ve purchased cell packs and growth flats.)
- Light is not required for geranium seed germination. Provide a warm area between 70 and 75 degrees (21 to 24C). They fit perfectly on top of my refrigerator, where I placed them.
- Open the plastic cover when you see green sprouts to let air circulate, but keep it there. Ensure adequate lighting for your seedlings. Remove coverings once there are two real leaves (the first leaves are seed leaves). Before putting seedlings into separate pots, give them a week or two to grow.
- Keep the soil mixture wet but not drenched. It’s best to water from the bottom up. When the tops of the pots are wet, take them from the shallow tray of water.
Geraniums from seedseedling care
- Plant your seedlings on a window sill that receives plenty of sunlight—ideally, one that faces south—or place them under fluorescent lights that are on for 12 to 14 hours each day. Using a timer makes this simple.
- Feed your plants with a water-soluble fertilizer once a week, half-strength.
- Pinch off the tips of the plants while they are actively developing to keep them compact and encourage branching.
- See seedling care and hardening off for details on how to take your seedlings outside and when to do so.