Thorns are a common natural defense for plants. By growing spikes and thorns on leaves and branches, plants can fend off natural predators, allowing them to continue growing undisturbed. This survival strategy has failed to deter human gardeners, however, who grow a wide variety of thorny plants for their decorative value.
Roses are among the best-known thorny plants. They vary greatly from plant to plant, with some growing bushy and others preferring to climb, and those plants have blooms with a dazzling array of colors, sizes and scents.
To plant roses, cut rose hips open in late summer or fall and scoop out the small, white seeds. Rinse them, wrap them together in a damp paper towel and place the towel in a food storage bag. Place the bag in the fridge for four or five weeks to stratify the seeds, then begin to check them every two weeks. When you notice small root poking out of several seeds, plant them in small pots, covered with 1/4 inch of dirt. Keep the soil damp and at room temperature for a few days until the seeds emerge.
Known for its vibrant green, spiky leaves and bright red berries which last through the winter, holly is associated with Christmas festivities and often used to build holiday wreathes. Holly seeds are surrounded by a protective seed coat which shelters them through the winter but makes it difficult to germinate new seeds. To propogate holly seeds, carefully pick the pulp off the seed, then thoroughly wash the seeds in cold water to remove any trace of seed pulp. Lightly cover the seeds in fertile, well-drained soil and keep them moist and at room temperature until the seeds start to emerge.
Cactii are tough, spiky plants evolved for some of the most hostile environments on earth. Cactii have tough, outer hides designed to minimize water loss and store moisture inside and are protected by spikes to protect them from desert animals. There are many different species of cactus, but most require similar circumstance to grow from seed. Moisten sandy cactus soil and sprinkle 6 to 10 seeds on the surface. Place the pot in a warm, sunny location with as much light as possible and wait. Once some of the seeds start to germinate, lightly mist the seeds to stop them from drying. Every 3 to 4 days, water the soil until the seeds become established. Once your cactus takes root, it will require little or no water to survive.