Barrel Cactus Germination

Growing Medium

• Barrel cactus grows reliably from seed in the right growing environment. Cactus seeds, accustomed to the dry, rocky environment of the desert, germinate best in a growing medium that resembles their natural habitat. Mix together equal parts perlite and sphagnum peat to create a growing medium that provides good drainage and support for the developing seedlings. Use propagation trays 4 to 5 inches deep. Select trays that have holes in the bottom for water drainage.

Sowing Seeds

• Fill the seed flats with the peat and perlite mix to a 1/2 inch below the top of the pot. Place the barrel cactus seeds on top of the mix 1 inches apart. Sprinkle a thin layer of clean coarse sand over the top of the seeds. Barrel cactus seeds are small, and watering can disrupt the seeds during germination. Water from the bottom up by placing the tray in a sink. Fill the sink until it comes two-thirds up the side of the pot. Leave the tray in the water until the top of the planting medium feels damp.

Seed Germination

• Barrel cactus seeds germinate best in a temperature range between 68 and 86 degrees Fahrenheit, according to the U.S. Forest Service. Start seeds in winter in a greenhouse. Place the seed trays on a heating pad, available at garden centers, if the temperature falls below the optimum range. Barrel cactus seeds can take up to a year to germinate. Keep the seed flats slightly damp during germination by placing the trays in a water bath when the top starts to feel dry.

Transplanting Seedlings

• Transplant barrel cactus seedlings into individual 2-inch pots once they reach 1-inch tall. Create a potting medium for the seedlings by mixing together equal parts perlite, sand and potting soil or peat. Slide a butter knife under the cactus seedling and lift it from the tray, keeping a clump of dirt around the roots. Fertilize barrel cactus seedlings once a week using a 20-20-20 fertilizer. The University of Arizona Extension recommends diluting the fertilizer to half the strength recommended on the package label.