The prickly pear cactus, Opuntia compressa syn. O. humifusa, is a native of Mexico, but it is often found in dry desert areas. For generations, the prickly pear cactus has been used for food. The leaves are peeled, fried and eaten and the seeds are ground into flour and made into pancakes or flatbread. Prickly pear cactus is hardy in zones 4 through 10. A mature prickly pear cactus can grow 6 to 18 inches in height and 12 to 30 inches in width.
Fill shallow pots or a tray with cactus soil. This special soil is sold at most garden centres or made at home by combining 6 parts of sand with 4 parts of leaf mould. Inspect the soil and remove any lumps.
Water the soil in the pots until water runs out the bottom. The soil has to be moist, but not soggy.
Place the prickly pear cactus seeds in a jar and shake the jar hard for five minutes. Or take a piece of sandpaper and scratch the top surface of the prickly pear cactus seed coat. The seeds have a tough exterior and this helps germination.
Test the prickly pear cactus seeds to see if they are viable. Fill a small bowl with water and add the prickly pear cactus seeds. Throw away any seeds that float. The viable, healthy seeds sink to the bottom of the bowl.
Lay one prickly pear cactus seed per pot onto the centre of the soil. Fill a tea strainer with soil. Tap the sides of the tea strainer and barely cover the seed with the fine soil that comes out.
Place the pots into a clear plastic container that has a clear plastic snap-on lid. Pour in 1/4 inch of water into the bottom of the container. This will keep the soil moist so the seeds don't dry out. Mist the surface of the soil with a fine spray of water. Snap on the cover. If the water level goes below 1/16 inch, add more water to the container. Only water the prickly pear cactus from the bottom until it is older.
Place the container in an area that stays around 21.1 degrees Celsius, under fluorescent grow lights. The distance between the soil and the grow lights should be 12 to 15 inches. Turn the lights on for 12 to 18 hours a day.
Remove and replace the snap-on cover with a piece of muslin when the seeds germinate. Secure the muslin to the container with string or rubber bands.
Place a thin layer of tiny aquarium gravel over the soil's surface around the prickly pear cactus seedling. The gravel supports the cactus so they don't fall over. It also helps the soil to retain moisture.
Inspect the seedlings daily. If they are reddish or brown in colour, move them to an area with less light. If they are yellowish in colour, move them to an area with more light. The seedlings should be dark green.
Remove the muslin for an hour or two daily when seedlings are 4 to 5 months old. Don't water from the bottom. Water them from the top of the soil.