Growing to impressive heights and featuring a variety of colors, larkspur offers an excellent way to brighten up a garden. You should use caution when growing this plant, however, since it can be dangerous to humans and animals.

Although the term can be used to describe Delphinium plants, larkspur more commonly refers to flowers in the Consolida genus. Christopher Cumo, editor of the 2013 book "Encyclopedia of Cultivated Plants," says this genus includes about 40 annual flowers native to Asia and Europe.

Larkspur flowers can come in hues of blue, pink, or white. The Missouri Botanical Garden says the plant usually grows two to three feet tall, but can sometimes reach a height of four feet. Cumo says the plant also features lobed flowers with an appearance similar to a crow's feet.

Early spring is an ideal time to cultivate larkspur, since it prefers cool and moist conditions. The seeds do not germinate well when outside temperatures are above 65 degrees.

If temperatures are too warm, you can start the seeds with the help of your refrigerator. The Cornell University Department of Horticulture says gardeners usually refrigerate larkspur seeds for two weeks before planting them. Anastasia Leon, writing for SFGate, says the seeds should be wrapped in a moist paper towel and kept in a plastic bag while they are being refrigerated.

Grow larkspur in an area with full sunlight. The plant can also tolerate areas with partial shade.

The soil is particularly important to the success of the plant. It should be fertile, slightly alkaline, and have good drainage. The Cornell University Department of Horticulture says root rot can easily occur in wet conditions, and that using a raised bed will minimize the risk of this problem.

Plant the seeds about a quarter-inch deep and about one inch apart. The soil should be kept moderately moist for the best result. You can allow the top of the soil to dry out, but there should be enough water to support the seeds at their planting depth.

The seeds should germinate in 20 to 30 days. Once they have started to produce leaves, you can thin out the weaker seedlings to leave about eight to 10 inches of space between the plants.

The Missouri Botanical Garden says larkspur flowers will bloom between June and August. For an earlier flowering, you can start seeds indoors about eight to 10 weeks before the last expected frost date of winter.

Deadheading spent flowers will help prolong the blooms. Larkspur can be used to create borders in the garden or cut flower displays. The Cornell University Department of Horticulture says the flowers retain their color when dried for display.

Larkspur is not susceptible to many problems related to pests or diseases. However, the Missouri Botanical Garden you might notice some issues with powdery mildew.

The Consolida genus name stems from the Latin word for "to consolidate or make firm." This name is a reference to larkspur's former use as an herbal remedy to stop bleeding and heal wounds. The plant was also used in treatments for head lice.

Taking larkspur internally is not recommended. All parts of the plant are toxic to humans, especially the seeds. The U.S. Department of Agriculture says the plant can also cause nervousness, weakness, and vomiting if consumed by an animal.

Wash your hands after handling larkspur. This step will ensure that you do not accidentally transfer toxins from the plant to any food you handle.