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How to Care for Carnivorous Plants During Dormancy



As the weather cools towards the end of the year many plants begin to die back for their winter rest, temperate carnivorous plants are no different and go through the same process.

Many temperate carnivorous plants grow in climates that have cold winters with a shortened photoperiod which is when they begin to lose their leaves and stop actively growing until the weather warms in spring and there is a longer photoperiod. Some carnivorous plants, such as tuberous Drosera, have a dormancy during the hot dry summer and lay dormant as a tuber until the cooler wet seasons occur. It is important to know the dormancy requirements (if they have any) for your plants in order to ensure they are long lived healthy plants.

For first time growers or even for growers placing their plants in dormancy for the first time it can be a daunting thing. Dormancy is often mistaken for a plant dying due to the blackening of leaves or sometimes plants during down to a rhizome. This blog will outline what dormancy is and how to care for your plants during that time.

Why do plants need a dormancy period?


Dormancy is a winter rest from which plants store energy whilst there is a reduce photo-period and colder temperatures. Naturally this often occurs from late October to March. In the plants natural habitats, they have adopted this growth pattern to suit their environments in order to live happily and healthy for many years. Therefore, denying them their natural growth pattern will often cause plants to die over time.

What carnivorous plants require a dormancy period?


- Sarracenia (North American Pitcher Plant)

- Dionaea (Venus flytrap)

- Darlingtonia (Cobra-lily)

- Temperate Drosera (Sundew)

- Temperate Pinguicula (Butterwort)


In order: Sarracenia flava var. atropurpurea, Dionaea muscipula 'Dentate', Darlingtonia californica, Drosera rotundifolia, Pinguicula grandiflora in my greenhouse during the growing season.


What plants do not require dormancy?

(Plants which can be kept inside year-round)


- Nepenthes (Tropical pitcher plant)

- Mexican Pinguicula (butterwort)

- Heliamphora (Sun pitcher)

- Sub-tropical and Tropical Drosera (Sundew)


In order: Nepenthes 'Gaya', Pinguicula 'Tina', Heliamphora heterodoxa x minor, Drosera x Helen


Others:

These plants listed below do also not require a dormancy period however I have kept these in an unheated greenhouse year-round in the UK without losses, sub-tropical may die down to the roots and come back in Spring:

- Cephalotus (Albany Pitcher Plant)

- Sub-tropical Drosera (capensis, aliciae, spatulata for example) (sundew)

- Utricularia (bladderwort)


In order: Cephalotus follicularis, Drosera aliciae, Utricularia sandersonii


What does dormancy look like?


Dormancy is often firstly identified by blackened or browning of the tips of leaves. During dormancy, plants may have little or no leaves at all and some forms a hibernaculum (winter resting bud). See below a selection of plants and what they look like during dormancy:

Sarracenia:
The browning of lids/ pitchers in Sarracenia is the first signs of dormancy. The pitchers will eventually go completely brown, and they can be cut back like in the last image.

Phyllodia:
In the autumn, Sarracenia often produce phyllodia, a non-carnivorous flat leaf which functions as a normal leaf on the plant. The plant can produce phyllodia any time of the year and you can choose whether to cut it off or not.

Dionaea:
Flytraps will often start with blackened tips to the traps and will stop producing leaves during dormancy. Over the winter they may only have a couple of leaves or none at all. Flytraps can tolerate below freezing temperatures providing they will be thawed by late morning. Some may even keep their traps over winter and barely die off.

Darlingtonia:
Similar to Sarracenia, Darlingtonia pitchers will often brown or yellow and die off. However, I find they often keep their pitchers over winter and die off when new ones are produced in Spring.

Temperate Drosera:
Firstly, your Drosera will lose all of it's leaves, they will go brown and can be cut back. Most Temperate Drosera will produce a hibernaculum during the winter which is a tight winter resting bud to protect the plant. The hibernaculum will either be green or purple in colour, they can be frozen, or snow covered and still survive the winter perfectly find. Other Drosera such as Drosera binata and Drosera regia sometimes make a similar tight bud or sometimes die off completely and come back from the roots in Spring.

In order: Drosera filiformis, Drosera anglica and Drosera intermedia 'alba' hibernaculum


In order: Drosera binata var. dichotoma died down for winter (Image 1 & 2). Drosera regia forming a winter bud kept in an unheated greenhouse.


Temperate Pinguicula:
Like Temperate Drosera, Temperate Pinguicula will lose all of their leaves and then form a hibernaculum. You know when the plant is about to lose its leaves because a dark purple centre will form at the crown of the plant which will be the hibernaculum. Some Pinguicula will produce gemmae which is a cellular bud that can be attached from the parent plant and sown to create new plants which will be found at the base of the hibernaculum.

In order: Pinguicula grandiflora about to go dormant with purple hibernacula at the centre. Fully formed hibernaculum with gemmae at the base. A cluster of hibernacula and gemmae.


What do plants coming out of dormancy look like?


When the weather starts to warm up in Spring the plants will start to resume growth, these images show healthy plants coming out of dormancy:

Sarracenia - Mature plants will firstly send out flower spikes before pitchers begin to form, younger plants will start with new pitchers from the crown of the plant and open once they get to the right height:
Dionaea - Flytraps will begin by producing new traps from the crown of the plants, often followed by flowers:
Darlingtonia -Mature plants will firstly produce flowers followed by new pitchers which start lighter in colour and darken with age, similar to Sarracenia:
Drosera - Those from hibernacula and from the roots will begin to unfurl new leaves:
Pinguicula - Similar to Drosera, will start to open up from hibernacula and produce new leaves and often followed by flowers:

How to care for your plants when they are dormant?


Where to keep your plants?

If you keep your temperate plants in an unheated greenhouse or unheated conservatory year-round, then they will naturally enter dormancy when the weather drops. Similarly, if you keep your plants outside then that is also good for allowing dormancy, just be aware if you live in an area which freezes for long periods of time (constant for days) then your plants may need some protection.

In order: My unheated greenhouse in Spring, my unheated greenhouse snow covered in winter, the inside of my snow-covered greenhouse. Plants are frozen but will often thaw out by the afternoon each day we have a freeze.


If you keep your plants inside during the active season, then it is important to respect their dormancy requirements and offer it when it is time. A chilly windowsill, or a cool room for example is unlikely to be cold enough to ensure a proper dormancy occurs. Temperate carnivorous plants often experience long periods of temperatures down to 0°C, especially from where they are most native in the south-east of the United States. They can even survive below freezing, some species can go down to -15°C, such as Sarracenia purpurea. These plants are very hardy which is often a surprise to many growers!

A collage of images of my outside bog barrels during the winter frozen and snow covered. Plants are subject to the elements and not protected with never any losses. Even Drosera capensis which have come up as weed are often frozen and still survive the winter.


You can keep your plants in an unheated greenhouse, conservatory, garage, shed, porch or similar. It is important to transition your plants into these positions as the temperature begins to drop around October. Do not place your plants straight into a cold spot from a heated room, start day placing your plants in their dormancy spot during the day and then bring then in each evening in the coolest spot in the house, repeat this for a while before leaving them outside during winter.

Watering

Even though dormant, your plants still need to be damp, never let your plants dry out completely during dormancy as this will kill them. Watering should only be reduced so that plants are not constantly sitting in water.

If you have planted bogs, containers or barrels outside which are naturally watered by rain then you do not need to worry about plants being too wet, due to the air flow there is less chance of mold or rot forming. There is a higher risk of this in more humid environments such as greenhouses and therefore should be reduced.

Lighting

During dormancy, plants do not need to be in a dark spot, they should still receive the natural photoperiod during winter, so if placing in a shed or garage then by a window would be best.

Feeding


During dormancy, plants are not actively growing and do not feeding. Even plants with traps remaining on a plant whilst dormant are unlikely to function due to the cold.

Commonly asked questions:


I do not have access to a cold spot or live in a country which has no winter, what can I do?

If you live in a flat with no garden or balcony for example or even a country which is warm for most of the year, then you can still keep temperate carnivorous plants and give them the dormancy period they require. You can use the fridge method; this is the process where you place your potted or uprooted plant in a plastic bag and place in the fridge from Halloween to Valentine's Day as a rough guide.

I’m worried my plant is dead, how can I tell?

Sometimes your plants may die down completely during dormancy having one or no leaves at all and so might assume the worst, the best way to tell is to uproot the plant and check the rhizome (flytraps and Sarracenia) which should be white/pink or whether there is a hibernacula (Drosera and Pinguicula) which will be a small tight cluster often green or purple in colour.

A healthy Sarracenia rhizome cut back for winter
Can I skip the first dormancy?

For first year seedlings or even plants purchased from somewhere like a warm garden centre you may wish to skip the first dormancy for your plants and grow them inside if this is your preferred way, but this should only be done once and not constant. However, seedlings can happily survive in an unheated greenhouse in their first year over winter.

For mature plants over a year or plants purchased in winter by sellers who give dormancy then they should receive dormancy as usual.

Some year old flytrap seedlings kept in my unheated greenhouse over winter

When is the best time of year to purchase a plant?

The best time to purchase a temperate carnivorous plant is in winter when plants are dormant. This is because plants will unlikely be affected by re-potting, dividing and being transported bare root, allowing you to a new beautiful plant in spring.

3 Sarracenia I received last year freshly potted up in the winter

Want more?


Why not check out my YouTube Channel (Carnivorous_plant_girl) where I have also covered a video on carnivorous plant dormancy:



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