Venus flytrap flowering: let it bloom or cut the stalk?

Recognizing a flower stalk

In spring, a mature Venus flytrap may push up something that looks nothing like a leaf: a bare stalk that keeps getting taller. NC State Extension describes clusters of white, cup-shaped flowers about 1.8 cm (0.7 in) across, each with five petals, on a leafless stalk 10 to 30 cm (4 to 12 in) tall, in May and June ^[5]. A CPN study of flytrap pollination describes the inflorescence as a branched cluster of 2 to 14 flowers, citing an average of six flowers on a stalk about 20 to 30 cm long, held well away from the traps ^[2].

Two things often come with it. In spring, as flower stalks emerge, many plants also put up upright leaves with long, narrow petioles; these are leaves and carry traps ^[6]. And the timing follows the seasons even indoors: wild plants flower in late May and June ^[1], an early study found flowering is triggered by day length ^[2], and the author of a CPN article on indoor flytraps reports that his plants under 15 hours of LED light a day still tend to bloom in spring, presumably because they also get some sunlight ^[7].

None of this is a problem in itself. Flowering is the plant behaving normally. The question is whether you want it to spend the energy. The troubleshooter lists spring flowering as the explanation for a sudden tall stalk.

Why most sources say cut it

The sources reviewed here agree on the usual advice:

• The ICPS checklist recommends cutting off flower stalks as soon as you see them, to keep the plant from spending its resources on flowering ^[3].
• The New York Botanical Garden says flowering takes a lot of energy from the plant and can reduce the number of leaves it produces. It suggests cutting any unusual stalk-like growth back to near the base once it is about 2.5 cm (1 in) long ^[4].
• A CPN article notes that growers cut off and discard emerging flower stalks every summer to conserve the plants’ energy ^[8].

NC State Extension adds a related warning: professional growers find that plants denied dormancy year after year become less vigorous and may exhaust themselves by flowering at the wrong time ^[9]. None of these sources measures how much a single flowering season costs a healthy plant, so the advice is precautionary.

How to do it. Cut the stalk near the base with clean scissors while it is still short ^[4]. Then keep giving the plant strong light and food; the ICPS says a plant that stops producing leaves should be fed as soon as possible ^[3]. See feeding.

When letting it bloom makes sense

A large, vigorous plant can be allowed to flower if you want to see the flowers or try for seed. A weak, small or recently repotted plant is better off without the extra demand, given the energy cost the sources describe ^[4].

What the flowers do. Field observations in Florida found that flowers open in late morning, shed pollen on the first day, and present a receptive stigma on the second; petals and stamens wither after the third day as the fruit starts to form. An earlier study found that the flowers do not pollinate themselves ^[2]. In the wild, the pollinators are mainly small bees and beetles. A study in the plant’s native range found almost no overlap between the insects that visit the flowers and those caught by the traps, and suggested that the distance between flowers and traps may help keep them apart ^[10].

What that means indoors. With no bees around, a flowering houseplant is unlikely to set seed on its own, because each flower’s pollen is shed before its own stigma is ready ^[2]. Growers who want seed have to move pollen between flowers themselves.

Seed and seedlings. Flora of North America gives about 20 to 30 seeds per capsule ^[11], and NC State Extension notes that the capsules open upward in June and July so raindrops can knock the seeds out ^[5]. The ICPS sows flytrap seed on the surface of the mix, keeps it at 20 to 25 °C (70 to 80 °F) in a plastic bag under lights, and warns that seedlings grow slowly: up to five years to maturity without regular feeding, or about two years with heavy feeding in the traps ^[6]. Seedlings vary. Nurseries propagate selected plants, perhaps one in a thousand from seed, by tissue culture, so a seedling from a named cultivar will not necessarily look like its parent ^[6]. See sowing seeds.

Using the stalk instead of discarding it

A cut stalk can still be useful to an ambitious grower. A CPN article reports successfully using flytrap flower stalks as starting material for tissue culture with a home kit; any part of the stalk from base to top worked, though the flower cluster at the top was hard to sterilize ^[8]. For most people, leaf pullings taken at repotting are the simpler way to make new plants ^[12]; see leaf pullings.

Keeping a flowering plant strong

• Decide early: cut the stalk as soon as it appears if the plant is small or struggling ^{[3, 4]}.
• Keep the light strong and feed regularly through and after flowering ^{[6, 3]}.
• Give outdoor plants their winter dormancy, or keep indoor plants under strong lights all year; switching back and forth is what the sources warn against ^{[6, 9]}. See dormancy.
• Expect tall, upright spring leaves alongside the stalk; they are normal, not a sign of low light ^[6]. If upright, pale growth continues all season, see weak color and floppy growth.

The Venus flytrap profile covers the plant’s flowering in the wild and its conservation.