What Is the Germination Period for Geraniums?

Germination Period

• Geranium seed has a very hard seed coat and should be scarified, or scratched, to break open the seed coat. Geranium seed needs a germination medium with a pH of 6.0-6.2 and covered lightly with vermiculite. The soil should be maintained at a temperature of 70 to 75 degrees Fahrenheit and be kept evenly moist. Light is not necessary for germination. Stem and cotyledon emergence will take place in five to 10 days.

Growing On

• Once geraniums have germinated, reduce temperatures to 65 or 70 degrees Fahrenheit during the hardening off period. Spraying a growth regulator greatly increases branching and helps the geranium to be more bushy. Reduce watering and allow your growing medium to dry out in between waterings. Transplant seedlings into a sterile medium. At this point, give your seed geraniums temperatures of 70 to 75 F during the day and 65 to 70 F during the night.

Light Requirements

• Geraniums love light, and will flower earlier and branch better when given supplemental lighting. Use a grow bulb that emits red light. These bulbs can be found in most garden centers. Give your germinating geraniums 16 to 18 hours of light per day. This should be started at the first true leaf stage. These first true leaves will be the first set of leaves after the cotyledon (small rounded leaves) emerge. Maintain high light levels until transplanting outside.

Fertilization Needs

• Geraniums have a high fertilizer need during growth, and are one of the few commercially grown flowers that benefit from a fertilizer application immediately after cotyledon emergence. Start with a low phosphorus fertilizer like a 14-0-14 once a week. After a few weeks of growth, begin alternating this fertilizer with a 20-10-20. During low light periods, make sure to give a lower dose of fertilizer, and a higher dose during high light periods.