The Germination of Annual Flowers

Dormancy

• Some annual seeds must have their dormancy broken before they can germinate, using a process called scarification. Scarifying the seed weakens the seed coating so that moisture can penetrate inside and begin the germination process. For example, there are two ways to scarify morning glory seeds. Soak the seeds in warm water overnight to weaken the outer seed coating. Alternatively, scratch off the outer coating on one end of the seed with sandpaper or a metal file.

Soil

• Fine-textured soils that remain moist without becoming soggy help ensure even germination of the annual seeds. Use a potting mixture containing fine-milled peat moss and vermiculite, or a commercial mix formulated for seed starting, in indoor pots. Rake the top 3 inches of soil in an outdoor bed so that the soil is broken up and there are no dense clumps if you are direct seeding your annuals. Finer textured soils don't inhibit the stems and roots as they emerge from the seeds during germination. Heavy, clumpy soils may also retain too much moisture, which causes the seeds or emerging seedlings to rot.

Moisture

• Annual seeds germinate best when provided with an even amount of moisture. Water the soil before or immediately after planting. Seal seeds started indoors in a plastic bag to help retain the moisture in the soil throughout the germination period. Frequent irrigation is necessary outdoors to keep the seed bed moist and to prevent the top few inches of soil from drying out, especially for seeds planted during warmer weather. Mist the seed bed with a light spray of water as opposed to using a sprinkler system or hose because these produce a hard spray that can wash away the small seeds.

Temperature and Light

• The best temperature for annual seed germination depends on the plant variety, but most seeds will germinate when the soil temperature is between 65 and 75 degrees Fahrenheit. Annuals that flower in early spring may tolerate cooler soil temperatures and some annual vegetables, such as peppers, will germinate at higher temperatures. Many annuals, such as impatiens and petunias, also need light to germinate. Generally, the smaller the seed the more likely it is to require light, as these seeds are usually planted at or near the soil surface. Other annuals, such as zinnia, only germinate in darkness.

Germination Time

• The time it takes for a seed to germinate depends on the plant variety and whether the seed receives the light, temperature and moisture requirements for quick and successful sprouting. Most annual flower varieties germinate within one to two weeks after sowing. A few take longer to germinate, such as geraniums that may take up to three weeks to sprout. Seed packets usually indicate when to expect the seeds to germinate after planting.