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. Recommended Agave cultivar plants are: Agave 'Victoria-Reginae'; Agave americana; Agave americana 'Marginata'; Agave americana 'Media-Picta'; Agave angustifolia 'Marginata'; Agave attenuata 'Boutin Blue'; Agave bovicomuta; Agave celsii 'Nova'; Agave colorata; Agave desmettiana 'Variegata'; Agave desmettiana 'Zebra Stripe'; Agave 'Felipe Otero'; Agave franzosini; Agave geminiflora; Agave lechguilla; Agave parryii; Agave parryii 'Compacta Variegata'; Agave potatorum 'Verschaffeltii'; Agave pygmaea; Agave salmiana; Agave stricta 'Pueblensis'; Agave 'Shark Skin'; Agave sisalana 'Variegata'; Agave toumeyana; and Agave tequilana 'Weberi Blue.'
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. Recommended cultivars of Aloes are: Orange Aloe.(Aloe acutissima 'antaramorensis') ,Blue Aloe (Aloe acutissima) ,Aloe aristata 'Montana' Tree Aloe (Aloe bainsii) Aloe brevifolia Red Aloe (Aloe camronii) Climbing Aloe (Aloe ciliaris) Kokoerbom(Aloe dichotoma) Aloe distans 'Yellow Teeth'Aloe 'Dorian Black' Aloe ellenbeckii White Aloe (Aloe glauca) Aloe kedongensis Bergaalwyn (Aloe marlothii) Gold Tooth Aloe (Aloe nobilis) Tiger Aloe (Aloe nobilis 'Variegata') Aloe petricola Spiral Aloe (Aloe polyphylla) Coral Aloe (Aloe strata) SoapAloe (Aloe saponaria) Aloe traskii Medicinal Aloe (Aloe vera) Partridge Breast (Aloe 'Variegata') Aloe verdoorniae Aloe 'White Teeth'.
Fern plants are a beautiful landscape choice or a container perennial, because of the delicate graceful foliage. Fern plants are native to the U.S., and found growing on every continent on the Earth. Some ferns grow well as cold hardy plarts in some areas bordering arctic conditions. A gardener can find a fern perennial to buy in practically any nursery or mail order operation.
Florida tropical perennials are restricted for growing in many States, because of the lack of cold hardy resistance. Some gardeners prefer to plant Florida perennials in greenhouses, or to grow as an annual. Many recommended plants are: Desert Rose, Adenium obesum; Allamanda cathartica; Giant Yellow Shrimp, Barleria micans; Hallmark, Bulbine fruiticasa; Clerodendrum ugandense; Bleeding Hearts, Clerodendrum thomsoniae; Bat Faced Heather, Cupha ilvea; Sapphire Showers, Duranta erecta; Euryops; Bolivian Sunset, Gloxina sylvatica; Iochroma cyaneum; Jatropha integerrima; Ixora; Lantana camara; Orthosiphon stamineus; Pentas; Russelia equisetiformis; Russelia equisetiformis aureus; Stachytarpheta urticifolia; Stachytarpheta mutabilis.
Flowering Vine perennials grow fast to cover fences, lattices, walls, and not only offer rewards of flowers, but many interesting flowers in colors of red, blue, white, pink, and yellow. If planted and grown in the sun, the flowering vines require little care of vine maintenance. Recommended flowering vines to plant are Coral Vine, Antigonon leptopus; White Coral Vine, Antigonon leptopus 'Alba'; Jekyll Island Vine, Bignonia capreolata; Tangering Beauty, Bignonia capreolata; Night Blooming Jasmine, Cestrum Nocturnum; Bleeding Hearts, Clerodendron thomsoniae; Lavender Trumpet Vine, Clytostoma callistegoides; Carolina Jasmine, Gelsemium sempervirens; Heart Vine, Ipomoea batatas; Chinese Jasmine, Jasminum polyanthum; Brazilian Firecracker Vine, Manettia inflata; Mailbox Plant, Mandevilla x Amblilis; Red Mandevilla, Mandevilla sanderi; Peaches and Cream, Mandevilla 'Peaches and Cream'; Pink Mandevilla, Mandevilla splendens; White Passion Vine, Passiflora; Blue Passion Vine, Passiflora x Alato-Caerulea; Red Passion Flower, Passiflora coccinea; Lady Banks Rose, Rosa banksiae; Blue Glory Vine, Thunbergia battiscombei; White Sky Vine; Thunbergia grandiflora; Confederate Jasmine, Trachelospermum jasminoides; Blue Wisteria, Wisteria sinensis; White Wisteria, Wisteria sinensis 'Alba';
Groundcover perennial plants are beautifully colored and fast growing, to keep soil erosion under control. Recommended groundcover plants are: Ajuga reptans 'Burgundy Glow', Burgundy Glow; Allium tuberosum, Society Garlic; Arachis glabrata, Perennial Peanut; Ardisia japonica 'Variegata', Ardisia japonica 'Variegata'; Aspidistra elatior, Cast Iron Plant; Aspidistra elatior 'Variegata', Aspidistra elatior 'Variegata'; Apsidistra lurida 'Milky Way', Apsidistra lurida 'Milky Way'; Asystasia gangetica, Ganges Primrose; Curculigo capitulata, Palm Grass; Ficus repens 'Variegata', Creeping Fig Vine; Ficus repens 'Variegata', Ficus repens 'Variegata'; Houttuynia cordata 'Chameleon', Chameleon; Liriope; Liriope muscari 'Big Blue', Border Grass; Liriope muscari 'Royal Purple', Liriope muscari 'Royal Purple'; Liriope muscari 'Super Green Giant'; Liriope muscari 'Variegata'; Liriope muscari 'Silver Dragon'; Lysimachia congestiflora 'Eco Dark Satin', Golden Globes; Ophiopogon intermedius 'Aztec'; Ophiopogon japonicus nana, Dwarf Mondo Grass; Ophiopogon planiscapus 'Ebony Knight', Black Mondo; Persicaria capitatum, Jump Seed; Persicaria microcephala, Red Dragon; Setcreasea pallida, Purple Heart; Setcreasea pallida, Pale Puma; Pseuderanthemum alatum, Chocolate Soldiers; Rubus calycinoides, Emerald Carpet; Scuttelaria longifolia, Red Fountain Sage; Spilanthese oleracea, Eyeball Plant / Toothpaste Plant; Trachelospermum asiaticum, Asiatic Jasmine; Tulbaghia fragrans, White Fragrant Garlic; Tulbaghia violacea, Society Garlic; Tulbaghia violacea 'Tricolor', Tricolor, Society Garlic; Vinca major 'Maculata', Periwinkle; Vinca major 'Variegata', Periwinkle; Vinca major 'Wojo's Gem'.
Herbacious perennial plants freeze during the winter, but return in the following spring to produce flowers of many colors and rare forms. Recommended cultivars are: Bee Balm, Monarda didyma 'Jacob Cline'; Blue Butterfly Flower, Clerodendrum ugandense; Blue Woodland Phlox, Phlox divaricata; Brunfelsia Pauciflora; Buckeye, Red, Aesculus pavia; Butterfly Bush, Buddleia lindleyana; Cestrum aurantiacum; Cigarette Plant, Cuphea micropetala; Clerodendrum bungeii; Cone Flower, Echinacea paradoxa; Cuphea 'Allyson'; Devil Star Lily, Clerodendrum puniculatum; Echinacea 'White Swan'; Echinacea purpurea; Firebush, Hamelia patens; Flowering Maple, Abutilion x hybridrum; Gaillardia 'Pin Wheel'; Lestrum fasciculatum 'Newellii'; Liatris spicata 'Blazing Stars'; Liatris spicata 'Floristan'; Lions Head, Leonitus leonarus; Obediant Plant, Physostegia virginiana; Orange Shrimp Plant, Justicia ovata; Orange Tongue Plant, Justicia leonardii; Phlox maculata 'Alpha'; Pink Tongues, Justicia carnea; Platycodon grandiflora; Plumbago auriculata 'Monott' PP7822; Princess Flower, Tibouchina urvillenana; Purple Butterfly Bush, Buddleia davidii 'Lochinch'; Red Cigar Plant, Sinningia sellovii;Red Prince, Weigela florida; Red Shrimp Plant, Justicia brandegeana 'Red'; Mouth of Hollywood, Rehmannia Elata; Rudbeckia hirta 'Becky Mix'; Ruellia brittoniana 'Katie'; Ruellia elegans; Scarlet Butterfly Lily, Odontonema cuspidatum; Shasta Daisy, Leucanthemum x superbum 'Alaska'; Shower of Gold Shrub, Galphimia glauca; Tecoma stans 'Yellow Bells'; Turks Cap, Malvaviscus drummondi; White Tongues, Justicia carnea; Yellow Creeping Jenny, Lysimachia nummularia 'Aurea'; Yellow Shrimp Plant, Justicia brandegeana 'Yellow'; Yellow Tongue Plant, Justicia aura.
Yucca is a genus of evergreen plants, with approximately 40 species that grow in dry, desert-like areas. However, this is a common misconception, because members of the Yucca family can be found growing in 30 of the States in America, from New Jersey, down to Florida, and west to California. Yuccas can be grown as small shrubs or yucca trees, up to 30 feet tall, depending upon the yucca species. Yucca has lance-shaped leaves growing in a rosette pattern, on a woody stem or trunk-like frame. Yucca plants may vary dramatically in color from shades of green, to white or yellow stripes, to blue-green hues, as with Yucca rostrata, a jewel for any garden. Most yucca plants are stiff and sharp pointed, like the Spanish Bayonet (Yucca aloifolia), while some yuccas have flexable soft leaves, such as Golden Garland Yucca (Yucca flaccida). The flower blooms of yucca grow in summer, and develop into a beautiful, creamy-white pendulum of bell-shaped flowers that tower 8 feet above the mother plant. Yuccas are very adaptable and are among the oldest living trees in the world. The Joshua Tree (Yucca brevifolia), Yucca filimentosa (Bear Grass or Adam's Needle) is among the most cold-hardy and widely grown varieties. The strong, stringy filament (fiber), that run a course from the needle tip, down the margin of the leaf, was used by native Americans for making into garments and possibly the treating of war wounds. The roots of Yucca were also used to make soap. The primary use for yucca plants in todays landscapes are for their ornamental beauty, like we find in Yucca flaccida 'Golden Sword', in terracotta pots or in ground landscape plantings. Some people use Yucca aloifolia 'Spanish Bayonet', Yucca treculeana 'Spanish Dagger', or even Yucca brevifolia 'Joshua Tree', as security hedges for their beautiful and exotically bazaar, stiff leaves, hence the nickname, "Burlars' Nightmare." Yucca plants are typicall sunlovers, growing in well drained soils, but are adaptive and often grow faster in moderately moist areas, such as the Southeastern U.S.. Recommended yucca cultivar plants are: Yucca aloifolia; Yucca brevifolia; Bear Grass, Yucca filamentos; Bright Edge, Yucca filamentosa; Golden Garland, Yucca flaccida; Golden Sword, Yucca flaccida; Ivory Tower, Yucca flaccida; Variegata, Yucca flaccida; Silverstar, Yucca elephantippes; Soft Leaf Yucca, Yucca recurvifolia; Spanish Dagger, Yucca treculeana; Rigida, Yucca rostrata; Linearis, Yucca rostrata; HesperYucca paviflora; Cordyline 'Baueri.'
Patrick A. Malcolm, owner of TyTy Nursery, has an M.S. degree in Biochemistry and has cultivated perennial plants for over three decades.Article Source: ArticlesBase.com - Rare And Exotic Garden Perennials For Landscape Planting