Drosera Care, Cold Hardy

Drosera, Cold Hardy

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The United States is home to several species of cold hardy sundews, such as Drosera anglica, D. filiformis, D. intermedia, D. linearis, D. rotundifolia, and D. tracyi. While there are certain idiosyncrasies that vary from species to species and hybrid to hybrid, the general care is the same for all of them. Use the following as a guideline to growing cold hardy sundews.
Drosera rotundifolia
Drosera filiformis
Drosera filiformis x intermedia

USDA Zone of Native Habitat: Zone 2-8

Most sundews found in the United States occur naturally where wintertime temperatures can sometimes reach as low as 10°F (-12°C) for brief periods of time. In cultivation, it is always recommended to follow proper winter care when growing these sundews in zones 8 or colder, regardless of a plant's cold tolerance. See below for more information.

Where to Grow

Cold hardy sundews grow best outdoors as a container or potted plant. They make an excellent addition to any sunny deck or patio. You may also grow them in a pond or fountain, but keep the crowns above water. Because of their specific soil requirement, avoid planting them directly in the ground unless you have created a specific type of bog garden.

Sunlight

During the growing season, grow your sundew outside in partial to full sun. Provide 4 or more hours of direct sunlight for vigorous growth.

D. filiformis and flytraps have the same growing requirements.
They can grow together in the same pot.

Heat Tolerance

Most cold hardy sundews are quite tolerant of the summer heat since hey originate from areas, where temperatures above 90°F (32°C) are common during summer. (See above for information about its range.) However, in their native habitat, the soil temperature is moderated by a slow seepage of spring water.

If you grow your sundew in containers, you will need to pay attention to soil temperature. While it may not be necessary to shade your plant during the hottest parts of summer, you may need to top water your plants daily to prevent the roots from over heating. This occurs when the soil temperature approaches 110°F (43°). Monitor soil temperature whenever the daytime temperature rises above 100°F (38°C).

If you live in areas where temperatures routinely rise above 100°F (38°C) during the summer, watch Grow Carnivorous Plants DVD, Volume 1 for growing instructions specifically for desert climates.

Water

If you are growing your plant in a pond or fountain, keep the water level no higher than halfway up the pot. Avoid drowning the crown of the plant.

Soil

requires nutrient-free soil that provides good drainage and aeration. Use a standard soil mixture of 1 part peat moss and 1 part perlite. Never use potting soil, compost or fertilizer. These ingredients will kill your plant.

Winter Care

By early fall, your sundew will slow down in growth and all of its leaves will die off. This is perfectly normal. As the weather gets cooler, the entire plant will eventually shut down and form a small bud, called a hibernaculum, found resting on the soil surface. This is how your plant prepares itself for winter dormancy, which is triggered by cold temperatures (below 50°F or 10°C) and shorter daylight hours.

Even while dormant, your plant will still need to sit in a small amount of standing water to prevent the soil from drying out. Remove all dead leaves.

Don’t worry about over night temperature dips as low as 20°F (-7°). While dormant, your plant can certainly tolerate nighttime frosts with minimal winter protection.

However, plants are very susceptible to freeze damage when grown in containers. You will need to protect your dormant sundew when the temperature falls below 20°F (-7°C) or whenever there is both a combination of freezing temperatures and wind. Both types of winter conditions can certainly cause serious frost burn. To prevent frost burn, cover your plant with black plastic or a tarp, or move it into an unheated garage or shed.

As soon as the freeze is over and the temperature rises above 35°F (2° C), uncover your plant and allow it to continue its dormancy outdoors.

If you live an area where the temperature routinely goes below 32°F (0°C) for more than a week at a time, such as in zones 7 or less, you will need to winterize your container plants. Container plants can certainly tolerate brief freezes, but with prolonged freezes, your plants are at risk for frost burn.

In early to mid spring look for new leaves emerging from the hibernaculum.

For more information on winter care in cold climates, watch Grow Carnivorous Plants DVD, Volume 1.

Feeding

Although some growers like to feed their sundews, it is not necessary. Carnivorous plants have adapted to capturing insects on their own, and insects will naturally be attracted to your plant.

If you choose to feed your plant, use recently killed insects that will fit comfortably on the leaves. Avoid putting too much on the leaves, because the leaves will rot.

Do not feed your plant meat. Use insects only. When it comes to feeding your plant, it is very tempting to over do it. Keep in mind that none is better than too much. Feeding is not at all required during the winter months when the plant is dormant.

Repotting

For a robust sundew, repot it every year. Change the soil, and if necessary, put them in a larger pot. Changing the soil restores soil acidity, improves root aeration and strengthens the health of your plants.

Repotting is best done in late winter and early spring while the plant is still in its hibernaculum state. Although its roots are often long and quite distinct during the growing season, during dormancy the roots are generally small and difficult to distinguish. Just make sure when you repot your plant that the hibernaculum is in its upright position.

You can also repot your plant during its growing season. If you do so, make sure to keep the roots intact and undisturbed as much as possible.

When changing pots, use a tall one that will easily accommodate its long root system. Sundews tend to grow faster and bigger when their roots have room to grow. Large pots will also give your plants added protection during the winter.

Indoor Care

Because of sun requirements and winter dormancy, we do not recommend growing hardy sundews indoors, including terrariums. They grow best outdoors as container plants or in bog gardens.