With tubular leaves and hoods arched invitingly open, carnivorous New World pitcher plants (Sarracenia spp.) lure insects to their doom in U.S. Department of Agriculture plant hardiness zones 2 to 11. Growing from horizontal rhizomes, the plants also send up nodding, five--petalled, 1- to 4-inch purplish-red or greenish-yellow flowers in late winter or early spring. The tropical Old World pitcher plants (Nepenthes spp.) are mostly vining varieties, which produce brightly painted cup-like pitchers and spikes of brown or purple flowers in USDA zones 11 to 12.
Where they are hardy, Sarracenias can be grown in bog gardens or in the soggy soil at the edges of garden pools. In either location, they should receive full sun for at least six to eight hours per day and the water level should remain 3 to 6 inches below the surface of their soil. Only Sarracenia purpurea varieties are perennial north of USDA zone 6, but you can cultivate types not hardy to your area by planting them in 6- to 8-inch pots with drainage holes. Those pots should be kept standing in metal or plastic trays of shallow water -- preferably rainwater. Fill the pots with a mix of half peat and half sand and keep the water in the trays 1 1/2 to 2 1/2 inches deep at all times.
Nepenthes are hardy only in USDA zones 11 to 12 and prefer partial shade in constantly moist, humus-rich soil. They are generally grown as house or greenhouse plants, most often in 6- to 10-inch pots with drainage holes. Fill those pots with a mix of half long-fiber sphagnum moss and half perlite, and keep that medium constantly damp but not soggy. The light requirements for Nepenthes vary according to species, but most prefer partial sunlight -- at least three to four hours per day -- or bright, indirect light. If you can’t provide high humidity, choose Nepenthes types with waxy leaves, which can tolerate lower humidity levels.
Pitcher plants don’t usually require fertilization, as they derive all the nutrients they need from the insects trapped in their pitchers. If you want to make sure yours are being fed, mix 1/2 teaspoon of a soluble seaweed plant food such as 16-16-16 with 1 gallon of water and sprinkle the plants with it once a month from spring through autumn. Despite the fact that they eat bugs, pitcher plants can suffer from insect pests such as aphids, mealybugs, thrips, and scale. If you see what looks like green lice, bits of cotton, silvery patches or brown bumps on the plants, treat them with an oil and pyrethrin insecticide. Wearing goggles, a respirator, and protective clothing, mix 2 tablespoons of the concentrate into 1 gallon of water, and spray the plants thoroughly, repeating the process a week later.
In the colder zones, cut back any dead leaves on in-ground Sarracenias in late fall and cover the plants with 4 inches of a light mulch such as straw or pine needles. If your Sarracenias are growing in pots, move those pots to a location such as an unheated garage or sun porch, where temperatures remain cool but above freezing. If you prefer, you can dig up and wash off the tubers instead. After removing any foliage, place them inside a zipper-type plastic bag, accompanied by a handful of damp moss, and store the bag in a refrigerator until late winter or early spring. Nepenthes plants should be kept growing as houseplants during the winter months, since they don’t require a dormant period.