How to Germinate a Barrel Cactus

Moisten a well-draining container filled with a soilless seed starting mix until the medium just barely sticks together. Allow the temperature of the medium to rise to between 70 and 80 degrees Fahrenheit before sowing seeds. Measure the temperature with a probe thermometer.

Sow seeds in the prepared container, just barely pressing them into the moistened medium. Cover the seeds lightly with sand. Place pots inside a plastic bag or cover seeds that are sown in flats to raise ambient humidity and encourage better germination.

Watch for seedlings to develop. Barrel cactus may take months to germinate -- be patient. Remove excess condensation daily from the seedling cover, since too much moisture can lead to rot because seeds take so long to sprout.

Crack the cover on the seedlings once germination occurs to allow the seedlings to acclimate to ambient light. Allow the seedlings more time each day under natural light until they are ready to be uncovered for the whole day. Spend about two weeks acclimating them to ambient temperatures. Recover the plants toward evening if require to keep the soil temperature around 70 degrees.

Water the seedlings only enough to keep the soil barely moist. Touch the medium daily and do not water if the soil is not fairly dry. Water just enough to keep the soil damp and do not overwater. Correct watering may be the most difficult part of germinating barrel cactus.