Ask the Master Gardener: Don’t worry, pets are safe around carnivorous plants

There are approximately 40 carnivorous plant species found in the United States. You can purchase them at nurseries, florists, and garden centers that carry unusual plants or from a gardening catalog.

The pitcher plant is a member of the carnivorous family of plants. Photo by Jennifer Knutson

Dear Master Gardener: I think it would be fun to have a carnivorous plant. Are they easy to grow as a houseplant, where do I obtain one, can it be put outside during the summer, and will it eat my cat (just kidding)?

Answer: Carnivorous plants are a fascinating group of plants -- and you can grow one right in your home without any fear of losing a favorite pet! In nature they grow in bogs, which typically lack nitrogen, so they get the nitrogen they need from the bodies of insects or other small creatures they digest. There are approximately 40 carnivorous plant species found in the United States. You can purchase them at nurseries, florists, and garden centers that carry unusual plants or from a gardening catalog. Check to make sure they are nursery-grown and not dug up from the wild since most of them are endangered. Carnivorous plants are easy care houseplants, but do need lots of moisture. A terrarium is an ideal place to grow them because it simulates the warm, humid environment of their native habitats. These plants require a moist, acidic growing medium, which should consist of two-parts sphagnum peat moss and one-part coarse sand. They grow best in a bright spot (west, east, or south facing window). Use distilled or rain water to water carnivorous plants because tap water may be too alkaline or contain minerals. Lightly sprinkle water around the plant without getting the foliage wet and keep the soil damp all the time. Do not fertilize carnivorous plants. Like all green plants, they contain chlorophyll and manufacture food by photosynthesis. They also gather nutrients from the soil and gases in the air -- insects are a supplemental food source. Most carnivorous plants only need one or two insects per month in order to thrive. If you have fungus gnats or fruit flies in your home you are in business! If not, during the winter you may have to purchase freeze-dried insects from a pet shop. Carnivorous plants grow quite well outside during the summer if placed in a bright spot and will be able to collect plenty of insects on their own.

The most commonly grown carnivorous plants for indoors are the pitcher plant, Venus flytrap, butterwort and sundew.

  • The pitcher plant has modified leaves that resemble a pitcher. Insects are attracted to the cavity formed by the cupped leaf which is filled with liquid. Insects slip down the pitcher, are trapped, and quickly digested by the plant’s enzymes.

  • The Venus flytrap has a rosette of flattened leaves with a trap-like structure on the upper portion of each leaf. The teeth-like projections interlock and trap the victim inside, which stimulates the secretion of digestive juices. These juices digest the soft parts of the insect.

  • The butterwort typically has rosettes of flat leaves with upturned margins. The leaf surface is covered with minute, sticky hairs that catch small prey such as fungus gnats and fruit flies. The glands in the leaves secrete a liquid of enzymes and acids that quickly overcome and dissolve the unsuspecting prey.

  • The sundew plant consists of a rosette of foliage covered with tiny red hairs. These hairs exude a sticky, sweet smelling fluid that attracts an unwary victim, which becomes stuck in the fluid and is digested into plant nutrients.

Dear Master Gardener: I would like to purchase a shamrock plant for a St. Patrick’s Day decoration. Will it keep as a houseplant? If so, how do I care for it?

Answer: In March local florists and garden centers sell shamrock (Oxalis) plants to celebrate St. Patrick’s Day. These “shamrock” plants have green or purple leaves with three triangular-shaped leaflets and small, five-petaled white flowers. Oxalis are good houseplants. They do well in normal indoor temperatures, but cooler nights will prolong blooming. Place them in an area with bright, indirect light. Their roots are shallow and they seem to prefer being pot-bound. While they are flowering you can fertilize them every two to three weeks with a liquid houseplant fertilizer at half the recommended strength. An interesting characteristic of many Oxalis plants is the movement of their leaves in response to light levels. Their leaves open in bright light and close on an overcast day and at night.


Shamrocks purchased as houseplants for St. Patrick’s Day are not the same shamrock found in Ireland. The word shamrock comes from the Irish Gaelic word seamróg, which means “young clover.” The shamrock that is the Irish symbol is actually a three-leaf clover (Trifolium). According to legend, the shamrock was a sacred plant to the Druids because three was a mystical number in the Celtic religion. When St. Patrick, Ireland’s patron saint, brought Christianity to Ireland in the fifth century, he used the shamrock to explain the concept of the Holy Trinity.

March Gardening Tips

  • Prune apple (including crabapple) and other fruit trees either in March or April, as long as it is before buds break and growth begins.

  • March is the month to prune oak, maple, birch, honey locust, mountain ash, hawthorn, butternut, walnut, ironwood, and beech.

  • Check for black knot, a fungal disease, on chokecherries and other members of the cherry family. Look for hard swollen black galls (tumor-like growths) that form on branches and sometimes on trunks. Make the pruning cut at least four inches below the black knot gall. It is best to prune when temperatures are below freezing to prevent black knot spores from infecting the pruning wound. If possible, dip your pruners into a bleach solution between cuts.

  • By mid-March start vegetable seeds, such as broccoli, brussels sprouts, cabbage, cauliflower, and head lettuce. By the end of March start eggplant, okra, and peppers. Check seed packets to see how many weeks ahead of transplanting they should be started and proper planting depth. Keep in mind the last frost dates for our area -- there is a 10% chance the temperatures will go below 32 degrees after May 27 and a 20% chance after May 21. Memorial Day is a good target date.

  • By the middle of the month start seeds for annuals such as ageratum, coleus, dusty miller, nicotiana, dianthus (pinks), snapdragons, and verbena. Seed alyssum, cleome, moss rose, and salvia at the end of the month. Again, check seed packets for seed starting information as species and cultivars will vary.

  • Move plants you have been overwintering into a sunny window. Cut off dead leaves and stems and start watering. Fertilize when you see new growth.

  • Sharpen pruning tools with a sharpening stone or have them professionally sharpened.

  • Use a file to sharpen the blades of spades, shovels, trowels, garden forks, and other digging tools.

  • Prune hydrangeas to the first pair of buds above ground or three feet up if you want stronger, less floppy stems.

  • Prune grapes before new growth emerges.

  • Cut back yellow and red raspberry canes to four to five feet tall before new growth begins.

  • You can begin fertilizing houseplants this month when you see new growth. Fertilize with liquid fertilizer at half-strength.

University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. All information given in this column is based on university research. To ask a question, call the Master Gardener Help Line at 218-454-GROW (4769) and leave a recorded message. A Master Gardener will return your call.
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