The Care and Feeding of Pinguicula, Butterworts Ó 2004

By Karen Oudean

The word Pinguicula comes from Latin and means small and greasy. The description fits the plant. It has small rosettes of leaves that feel like they have been buttered. Many warm climate butterwort species have a long blooming season. The beautiful little African-violet-like flowers come in shades of yellow, white, pink, lavender, blue-violet, and purple, depending on the species or hybrid. The hardy butterworts have all the charm of woodland violets. They bloom in the spring in shades of blue and purple.

Fungus gnats, fruit flies and other tiny insects are lured to their death by the fungal odor of the butterwort’s leaves. The leaves produce a slippery ooze, which traps insects as they land to look for food. Struggling victims activate glands, in the leaves, that produce a digestive enzyme. The enzyme breaks down the edible parts of the little bodies. The leaves then absorb the nutrient solution. The carcasses remain, littering the leaves. During this process the leaves appear to move very little. The leaves of some species may slowly curl or dimple to pool digestive fluids around the bug. Grow these sparkling gems with your houseplants and all the plants will benefit. Butterworts are not hard to grow if one understands and provides for their few special needs.

A. Warm Climate Butterworts:

Species discussed: P. agnata*, P. caerulea, P. esseriana*, P. ehlersae*, P. ionantha, P. zecheri, P. moranensis*, P. primuliflora, P. laueana* and their hybrids

*Plants form tight rosettes with smaller, more succulent leaves in winter months.

1. Light Requirement:

a) Indoor Culture: Place the plant in any bright window at room temperature. Butterworts need lots of indirect light. If sunlight falls directly on the leaves for any length of time, the plant may gradually turn transparent and die. A lace or sheer curtain will give the plant protection from sunburn. In hot climates this may not be enough protection. Pull the plant just out of the path of the sunlight that comes in the window. If you have no suitable window, use two 32W fluorescent tubes in a shop light or a 23W compact fluorescent plant light in a desk lamp, placed 6” to 8” above the plants’ leaves. In terrariums, use high intensity plant lights and keep the tank out of the sun so the plants will not get cooked. 70°F is the best temperature. 10 ° higher or lower is still fine.

b) Summer Patio Culture: Place the plant in light shade or dappled light all day.

2. Water Requirements:

a) Indoor Culture: This is a bog plant. Never let the soil dry out. Keep the potted plant in a deep saucer or bowl of water during the growing season. I grow my plants in water trays. The water is about ¼” to ½” deep in winter months, 1” to 2” deep the rest of the year. Trays may be allowed to go almost dry between watering as long as the soil does not dry out. Use rain or distilled water.

b) Summer Patio Culture: This is a bog plant. Do not allow the soil to dry out. It is less of a chore if plants are in large pots, set in deep water bowls. While the plants are still in their semi dormant stage, pot them in large pots with holes in the bottom. Place the potted plants in a bowl that is at least 2” shorter than the pot. This will keep the butterworts from being submerged in water by a rainstorm. Check the water level often in hot weather. Do not fertilize. While you are on vacation, fill the water bowl to the top. The water level can drop to the bottom of the pot between watering as long as the soil stays moist. Use rain or distilled water.

3. Dormancy: Warm climate butterworts bloom best if they have 3 - 4 months of cool temperatures (40°F to 50°F) to rest. If you do not have an unheated room or cool greenhouse that does not experience freezing temperatures, put them in a cool window and treat them as house plants. They may be grown outdoors all year if you are in a frost-free climate. Request our Outdoor Bog Sheet.

B. Hardy Butterworts:

Species discussed: P. vulgaris, P. grandiflora, P. macroceras, and P. macroceras ssp. nortensis

1. Indoor Culture: The general care of hardy butterworts is the same as for the warm climate butterworts. The main difference is their dormancy. They will go dormant in continuous hot weather, sometimes reappearing in the fall for a short time before they take their winter nap. Hardy butterworts need a dormancy of 4 – 5 months of temperatures at or below 40°F. They will go into the tight leaf bud of dormancy for the winter, even in warmer temperatures. If your climate is extreme or outdoor culture is not possible, grow your plants in a cool southeast or southwest window, in the summer. When they go into their dormant bud in the fall, pack them in damp (not soggy) sphagnum moss or damp paper towels and place them in a labeled and dated zip-lock baggie in the vegetable draw of the refrigerator for the winter. They may rot if they are kept at warmer temperatures. Repot them and place them in the window in the spring.

2. Outdoor culture: We have tested the hardiness of the temperate butterworts, mentioned above to 12°F with success for five years, in outdoor bogs, in the Pacific Northwest. See our Bog Sheet for easy building instructions. Container bogs for the patio are quick and easy to assemble. Plant your other hardy carnivorous plants in your container first. Place a mulch of 5/8”, or smaller, crushed gravel or medium orchid bark, 1” deep on top of the bog. Plant the butterworts by moving just enough of the mulch to tuck them into the soil. Gently push some of the mulch back over the soil and up to the base of the plant. Water the plants to clean them and settle them into the soil. In the winter, the plants form small tight buds that look like tiny green bulbs on top or half buried in the soil. The crushed gravel or bark will keep hard rains from washing these dormant buds away. The mulch also prevents the splattering of soil onto the plants’ leaves or the patio.

C. Potting Instructions: Winter is the best time to repot butterworts, as the roots are minimal at this time of year. Hardy butterworts form little green bulb-like resting buds with few or no roots. Many warm climate butterwort species and hybrids form tight rosettes of thick, succulent leaves while dormant. Their fleshy, white roots are extremely delicate. A light touch is very important. I use a mix 1 part peat and 2 parts fine, plug grade perlite for warm climate species that form winter rosettes. For warm climate species that do not form winter rosettes and hardy species that form winter resting buds, I use 1 part peat moss and 1 part fine perlite or sand. Mix and moisten the ingredients well. In the bottom of a 3”(or larger) pot, place enough orchid bark or crushed gravel to cover the holes so the soil mix stays in place. Fill the rest of the pot with soil mix. Press it firmly into the pot and mound the top of the soil slightly. When planting winter buds, tuck the blunt end just barely into the soil mix. If you are planting warm climate species or nondormant hardy butterworts, use your thumb or a spoon to make a depression, in the soil, in the center of the pot. Make sure the depression is large enough to fit the roots of the plant without bending or breaking them. If you received your plant bare-root, unpack it carefully and place it in the depression. If you are transplanting your plant, lift the root ball and a little soil mix with a spoon and place it in the depression in the soil. Gently, cover the roots with soil. If you feel you need to press the soil mix down, do it very lightly, so the roots will not be crushed. Tap the bottom of the pot to settle the soil. Place the potted plant in its water saucer or bowl. Water the plant overhead to finish settling the soil mix and rinse off the leaves.

D. For More Information: There is an excellent TIME/LIFE videotape at most public libraries entitled “Death Trap”. Timber Press sells the book “Carnivorous Plants of the World” by Pietropaolo and Pietropaolo. “ The Savage Garden” is a great new book by Peter D’Amato.