An attractive perennial with striking blue flowers growing on towering stalks, delphiniums (Delphinium spp.) are popular additions to any flower garden. The flowers grow quickly from seed and can adapt to a variety of climates as long as they receive regular watering and are planted in loamy gardening soil. Hardy to U.S. Department of Agriculture plant hardiness zones 3 to 7, delphinium seeds require a chilling period, called stratification, in order to germinate in the spring.
Store delphinium seeds in a moist but soilless mix for stratification. A mixture of four parts peat moss to one part construction sand or vermiculite is suitable for stratifying delphinium seeds. Place the mixture in a plastic container, and water it until it is moist but not wet. There should be no puddles at the bottom of the mixture.
After the medium is ready, add the delphinium seeds to the surface of the medium and cover with a thin layer of the growing medium. Place the sealed container in a warm location, such as beside a window receiving indirect sunlight or on top of a refrigerator. This will allow them to absorb moisture and ready themselves for the germination that will come after the long chilling period.
After three days, place the container in a cool environment. Suitable locations include the door tray, crisper or meat tray of a refrigerator. Delphinium seeds will need around three months of cold temperatures in order to germinate in the spring. The refrigerator is an ideal environment, because the seeds need to be kept at around 40 degrees Fahrenheit.
Once the container is placed in the refrigerator, the seeds will need little care until spring. Shake to maintain aeration of the medium once every one to two weeks.
After three weeks of chilling, remove the seeds from the stratification medium and plant into loamy potting soil, either in small seedling pots placed near a sunny window or directly into the ground of a flower garden. The seeds will germinate soon after being planted. Delphinium plants and seeds are poisonous, so exercise caution if children or pets are present.
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