The term, ‘perennial plant’, means simply that the plant returns following severe freezes, to grow again the next year. Trees are cold hardy tested perennials by nature, some trees that are evergreens and do not go dormant, but merely slow down during various seasons, and other shade trees enter dormancy and shed the leaves. Tree growth of shade trees may stop altogether in extremely cold climates, but in the spring, will surge with buds that open to flower and leaf out.
Great difficulties arise in assigning a plant, ‘perennial’, mainly because the primary determining factor, temperature range varies from year to year; and every century extreme cold temperatures may erase certain plant populations that have survived in areas before for decades or sometimes even centuries. A perennial plant may be a survivor, thus a “perennial” for a given growing area, then suddenly may become extinct in that growing area. The USDA has constructed a zone map that reveals averages of temperatures reached by the location in your State. This map is a nursery tool used to predict whether a perennial will live (cold hardy) in your area.
Agaves are a diverse genus of over 200 species of rosette, spear-like, leafed evergreen perennials. Agave typically grows as low shrub-like plants in dry or well-drained soils of the Southern part of the U.S. from New Jersey down to Florida, and then West to California. Many Agave species, such as Agave americana or Agave tequilana, have sharp recurved, protective teeth running along both sides of the blade of its semi-curved, lance-shaped leaves, with a sharp needle-tip lance at the end. There are Agave species, like Agave attenuata, and Agave stricta, that do not have sharp-teeth at all, but are smooth. The color variations of Agave plants range from shades of green, to silvery-grey, bluish-green, top yellow or white stripes, such is the case with Agave americana ‘media-picta’. The bloom of mother Agave plants are a beautiful array of pendulent bell-shaped, creamy-white flowers soaring high above the mother plant on a flower stem that may reach 20 feet or more for some agave species. The bloom period of a mother Agave plant is during the summer and the flower stalk is magnificent to behold, however, this event means the cycle of life ends for mother Agave and begins again for her Agave offspring. Agave plants are an excellent choice for rock gardens or well drained soils that lend themselves well to terracotta or cement planters. Agaves are fairly slow glowers so expect higher prices on these sunloving garden jewels at retail garden centers. Huge specimen agaves can be quickly delivered by semi-trucks.
The ancient Egyptians in 1500 BC grew the Aloe for healing, and while the Pharaoh held all the Jews in captivity, aloes were used as cosmetics and for the sacred healing power of this mysterious perennial. The Book of John, in the New Testament Bible, John 19-39, records that Jesus’ body was wrapped in linen cloths and aloes after the corpse was removed from the crucifiction cross before burial. Aloes are evergreen perennial plants that grow as shub-like, climbing or tree-like plants. The aloe plant leaves are fleshly, succulent, long tongue-shaped groups of rosettes, or as star-patterned limbs. Most forms of the aloe, 300 species genus, have toothed leaf blades with soft to piercing hard teeth. Aloe saponaria and Aloe vera are the two most commonly found containerized aloes in homes and gardens. Aloe vera plant extracts have long been used by mothers on their children for fast relief for minor cuts and burns. Aloe saponaria is cold hardy down to freezing temperatures and is widely grown in Southern gardens for the beautiful, coral-colored, tubular blossoms and for the making of medicated soap. Most aloe plants are small, 1-3 foot tall and width, however, a few tropical aloe species, such as Aloe marlothii grow into large, 120 foot succulent trees. Aloe plant varieties may vary enormously in color from yellow, red to blue-greens, or to spotted or striped with random variegation.