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Soil is not something people first consider when they think of pitcher plants. Because pitcher plants are famous for getting their nutrients from trapped insects, the other aspects of their horticulture can kind of fall by the wayside when people consider what it takes to keep them.
So how do you make soil for pitcher plants? Here are the basic things you need to know about composing soil for pitcher plants:
- Pitcher plants are American natives that come from the Southeastern part of the United States in areas with very poor soil.
- Pitcher plants do not need rich soil, but they need to be in a soil medium that drains
- Potted pitcher plants thrive in a low-fertility mixture of peat moss, bark, and vermiculite.
- Outdoor pitcher plants can be grown in slightly acidic soils.
- Outdoor pitcher plants are swamp plants and must be kept wet. Pitcher plants need boggy, moist soil and do well at the edge of water gardens.
- A combination of half-perlite and half sphagnum moss works well for pitcher plants at a ratio of 2:1. Horticultural sand (lime-free) can be incorporated for drainage as well.
- Indoor pitcher plants generally don’t require fertilization but can be fertilized with orchid food once a month from spring through fall. Be careful not to over-fertilize, which can lead to a build-up of minerals and deterioration in the plant.
- Peat is a controversial soil additive due to its effects on habitat damage and global warming, so many growers are moving towards peat-free mixes such as milled bark, horticultural grit, and perlite, at a ratio of 2:1:1.
Pitcher plants gather a lot of their own food from their surroundings and do not need a lot of extra help. However, because they evolved to live in a very specific habitat for adverse conditions, they need people who grow them to mimic those conditions for them to thrive.
Read on to find out more about how pitcher plants interact with the soil they grow in, and what you should grow them in for the maximum health and beauty of your plants.
What Do Pitcher Plants Need from Soil?
Despite the fact that they are classified as carnivorous, pitcher plants are the same as many other plants in what they need from the soil they grow in. Pitcher plants and all other plants are supported biologically by soil in the following ways:
- Soil gives root systems a way to anchor plants for stabilize itself, which prevents injury and makes biological processes more efficient.
- Pitcher plants breathe through the oxygen stored in the soil and use this oxygen to break down sugars and release the energy they need to live and grow.
- Pitcher plants draw water up through the soil and use that water to cool themselves, maintain cell size, transport nutrients, and as a raw material in the process of photosynthesis.
- Soil acts as an insulator to protect sensitive roots, which is vital to the survival of the plant during the hottest and coldest times of the year.
- Soil supplies nutrients and minerals to the plant.
Pitcher plants are unique in that they evolved to grow in environments with extremely low-nutrient soil. This drove these plants to evolve to uptake nutrients both through their roots and through the use of insect traps, or pitchers.
Pitcher plants drown their prey in these pitchers and take in nutrients from the dissolved carcasses of insects and other small animals. They get less of their nutrients through the soil.
Despite this, the soil composition used to grow pitcher plants is still very important. They need consistently moist soil, but they need soil that drains well too. They also don’t do well in rich organic soils, which are the opposite of the type of soil they evolved to grow in.
What Components Are Used in Pitcher Plant Soil Mixes?
Since pitcher plants are sensitive to the composition of the soil they’re grown in, growers have come to use a very specific set of soil amendments in conjunction with each other in order to make a soil mix that has the highest rate of success in growing pitcher plants.
Ratios of aerating materials to water/nutrient retention materials can vary, but it is important to have a mix of both in order to provide the kind of good drainage that pitcher plants require without drying them out.
These are the different kinds of soil amendments typically used to make a soil mix for growing
- Sphagnum/peat moss: Peat moss is the dead, fibrous material that forms when mosses and other plant life decompose in a peat bog. Peat moss is prized in gardening soils because it holds several times its weight in moisture and holds nutrients in the soil.
- Perlite: Perlite is a non-toxic, lightweight white soil additive made from superheated volcanic glass. Perlite provides excellent drainage and aeration to soil mixes, making it an important component for plants that prefer wet but well-drained soils.
- Vermiculite: Vermiculite is formed of hydrated laminar minerals and is used to add water and nutrient retention to soil mixes. Vermiculite is sterile and does not rot or mold, and is also organic, odorless, and long-lasting.
- Grated/milled bark: Due to the environmental concerns involved with mining peat moss, many growers have turned to grated or milled bark as an alternative. These mixes are available in garden stores and can be used as a substitute for sphagnum moss.
- Horticultural grit: Horticultural grit is a fine grit (1-6mm) with a neutral pH that is intended for use in homemade soil mixes. It is a crushed stone mixture that helps aerate the soil and particularly helps in breaking up very heavy clay soils.
- Horticultural charcoal: Horticultural charcoal is a good alternative to orchid substrate for people who want to keep pitcher plants in a similar soil consistency, because it is inert and does not contain rich nutrients like orchid soil does.
- Horticultural sand: Horticultural sand can be used to aerate heavy soils like grit or perlite. Playground sand can also be used in place of horticultural sand as long as it is well-washed before use to avoid any chemical residues.
When choosing soil amendments for pitcher plants, it’s important to avoid commercial soil mixes (which are too rich as a general rule) and compost, which is also too rich. Remember that for pitcher plants, drainage and anchorage are far more important than nutrients.
Pitcher Plant Soil Ratios
In general, pitcher plants will require a higher proportion of drainage material in their soil mixes than soil and water retention materials, so you’ll need to put equal or even more emphasis on soil amendments such as perlite and horticultural grit over peat moss or milled bark.
Here are two good soil mix ratios for pitcher plant soil mixes:
- 2 parts perlite to 1 part sphagnum moss
- 2 parts milled bark to 1 part perlite and 1 part horticultural grit
Keep in mind that the main things pitcher plants need out of their soil are both water retention and drainage. They don’t need much food from the soil, but they are water-dependent plants and need to have constant access to moisture.
Commercial Pitcher Plant Soil Mixes
While most potting soils found in gardening centers and home improvement stores are not suitable for pitcher plants because they are geared towards being rich with organic materials and fertilizing elements, there are a few soil mixes out there designed for pitcher plants.
Carnivorous plant mixes are made specifically for pitcher plants and other carnivorous plants. While they can be significantly more expensive than making your own potting mix because they are a specialty item, they can also take a lot of the guesswork out of pitcher plant soil.
Here are a few of the brands of commercial potting soil available that are suitable for use with pitcher plants:
- Rio Hamza Trading Carnivorous Plant Soil Mix: This potted plant mix is a fifty-fifty mix of perlite/peat moss and is all-natural with no additives.
- Josh’s Frogs Carnivorous Plant Soil Mix: A special mixture of peat and perlite that is suitable for pitcher plants, Venus fly traps, and sundews.
- Organic Earth’s Carnivorous Plant Soil Mix: An organic soil suitable for pitcher plant pots and carnivorous plant terrariums.
- Jessie Mae Carnivorous Plant Potting Soil Mix: A mixture of peat moss, washed sand, and perlite that is 100% organic with a light and airy mix that deters root rot.
Moisture Content in Pitcher Plant Soil
Pitcher plants are bog plants and want their soil to be wet the majority of the time. However, this level of moisture needs to be maintained right above the level of being soggy, which the pitcher plant will not like. Keeping a proper soil moisture level for bog plants can be tricky.
To avoid the soil from becoming too saturated with water, make sure that the pot you keep your indoor pitcher plant in can drain completely between waterings, and never allow your plant to be in standing water. This can cause the plant’s root system to rot.
One way to give a pitcher plant constant access to water is to make sure that it is in a well-draining soil mix and then set the entire pot in a tray of water so the plant can draw water as it becomes dry. Maintain 1/4 inch of water in the tray and fill with extra water when necessary.
For indoor plants, always use distilled mineral-free water or rainwater to add moisture to the soil, as pitcher plants are very sensitive to the chemicals in water treated for human consumption, such as chloramines.
Outdoor Pitcher Plants and Soil Moisture
Outdoor pitcher plants that are grown on the margin of a water feature such as a koi pond will usually get enough water from the water margin to be happy, but if they start to look dried out, make sure to supplement with extra water. Rain barrels are a good choice for this.
Another option for keeping outdoor pitcher plants while still maintaining control over the soil is to put outdoor pitcher plants in hanging pots and attaching them to the eaves of a roof.
Not only will they get plenty of food from the insects drawn by porchlights, it is much easier to maintain the levels of water they will receive from the soil when you can go around and water them from beneath with a spouted watering can made for houseplants.
Fertilizers in Pitcher Plant Soil
Because the pitcher plant is designed to scrape up every possible mineral and nutrients from its surroundings, if it is placed in soil that is too rich, it will become oversaturated with these minerals, and the health of the plant will suffer.
Pitcher plants typically do not need any additional fertilization past the nutrients that they can glean themselves through their prey, but if you have indoor pitcher plants and think they aren’t getting fed enough, you can use an orchid food diluted by half from spring through fall.
Rather than use fertilizers, it is better to provide a few freshly killed insects or dried insects every month to an indoor pitcher plant without access to trap its own food. Make sure that the insect is small enough to be submerged completely in the pitcher plant’s well.
Outdoor pitcher plants do not require fertilization at all, as they are ruthless hunters and will have plenty of insects to feast on, especially if they are placed near outdoor lighting.
Soil pH for Pitcher Plants
In their natural habitat, pitcher plants grow in acidic soils. Whether you use soil out in the garden or have your pitcher plants in pots in the house, you’ll need to make sure that your pitcher plant soil veers to the acidic side of the pH range.
There is an inexpensive, easy way to test your how acid or alkaline your soil is. To perform this test, you will need the following:
A soil sample of the soil you intend to use for planting
- White vinegar
- Baking soda
- Two cups
Once you have your soil sample, you first separate out some of the soil into a cup and pour half a cup of vinegar on the soil. If the soil fizzes or bubbles, it is alkaline. That means it is not suitable for pitcher plants and needs to be amended with plenty of acidic materials.
If there is no reaction, take a second bit of soil out of your sample and put it in the second cup, then add half a cup of water and mix well. Then add a half cup of baking soda. If the soil bubbles or fizzes, that means the soil is highly acidic, and pitcher plants will like it.
If there is no reaction to the baking soda or vinegar, that means that the soil has a neutral pH and should have some acidic materials added to make it suitable for pitcher plants.
What Components to Avoid in Pitcher Plant Soil
Aside from soil mixes with high organic content such as potting soil, orchid substrate, and compost or manure, certain kinds of sand should be avoided in pitcher plant soil mixes.
It is fine to use playground sand to replace horticultural sand if it is not available (or not cheap) in your area, but you will want to wash it carefully before use.
Avoid contractor’s sand, which can contain lots of silt and other clay-like materials, and also avoid beach sand, which has lime and salt that can hurt the plants. Pitcher plants are strictly freshwater bog plants and cannot tolerate salt.
I Used Bad Soil for My Pitcher Plant, Now What?
Sometimes people get carnivorous plants without knowing enough about their husbandry to really help them thrive. Without doing some background reading, many would-be gardeners assume the pitcher plant can pretty much care for itself.
However, if you plant pitcher plants in a rich organic soil and leave it that way, it will eventually die. Left without intervention, the pitcher plant may produce a few distorted leaves with no working pitchers and will rot.
To avoid this problem, you should repot your pitcher plant regardless of the season as soon as possible in a mixture of half and half peat moss and horticultural grit. Then be sure to read up more on your species of pitcher plant to make sure you don’t make any other mistakes.
How to Re-pot Pitcher Plants
Like other potted houseplants, pitcher plants require regular re-potting to be able to maintain a steady rate of growth and stay healthy. On average, pitcher plants should be re-potted every one to two years.
The best time of year to re-pot a pitcher plant is in early spring, before the plant begins to put on significant amounts of new growth. Re-potting is a stressful time for plants, and you don’t want to damage them when they have tender new leaves and pitchers starting to form already.
While the plant is still dormant, use the following method to re-pot a pitcher plant into new
- Remove the plant from its soil mix and gently remove as much planting medium as you can by brushing the plant gently off.
- Make a new pitcher plant soil mixture out of sand, horticultural charcoal, sphagnum moss and peat moss. Keep the ratios 2:1 for moss and sand/charcoal. Perlite and milled bark can also be used in place of horticultural sand and peat moss.
- Mix the ingredients of the soil mixture together thoroughly. Stand the pitcher plant in a new plastic planter and scoop soil gently into the pot to cover the roots.
- Tap the planter on the table to settle the soil in the pot, then top it off. Water the soil to
remove any hidden air pockets and top the soil off again as needed until it is just below the lip of the planter.
- Pitcher plants should be planted in plastic, rather than in terra cotta pots, which can lose salts too quickly.
It is easy to amend soil for pitcher plants that are houseplants in pots but amending an outdoor area for pitcher plants can be a little bit larger of an undertaking.
How to Amend Soil for Outdoor Pitcher Plants
When keeping pitcher plants, you may choose to keep your plants outdoors rather than indoors, and if you are living in an area where pitcher plants are native, you might not even have to amend the soil that much to keep them happy and healthy.
The biggest challenge to growing pitcher plants in the Southeast where they are native is that the Southeast also tends to have heavy clay soils, which do not drain well and are not suitable for growing pitcher plants.
If you are trying to grow pitcher plants in an area with heavy clay soils or rich organic soils, you will need to add a lot of low-nutrient aerating materials such as perlite or horticultural grit to break the soil up and decrease the nutrient uptake of the plants.
When grown outdoors, pitcher plants do best in warm, humid environments, but do require two elements to do well: a boggy garden environment and a period of winter dormancy.
How to Build an Outdoor Bog Garden for Pitcher Plants
One way to ensure happy outdoor pitcher plants is to build a habitat that is especially suited to them and their preferred environment. Since pitcher plants are naturally bog plants, one way to make them happy in your garden is to build a bog.
A bog garden is a good choice for people who already have (or want) outdoor water features such as koi ponds. Bogs occur naturally around low-lying areas and watery areas such as lakes, swamps, and streambeds.
To construct a backyard bog garden, perform the following steps:
- Dig a hole about two feet deep and as wide as you would like your garden bed to be. Line this trench with a sheet of pond liner and press it down so it contours flush with the whole.
- Leave at least a foot of liner exposed to accommodate for the bog settling. You can hide this liner edge later with mulch or rocks and boulders, which can be attractive garden features in and of themselves.
- Poke drainage holes around the edge of the liner, one foot below the soil surface. This will keep water from standing in the pool liner and rotting out the roots of the plants.
- Fill your bog garden with a mixture of 30% coarse sand or horticultural grit and 70% peat moss and native topsoil.
- Allow the bog to settle for one week and keep well-watered before you begin planting.
Other Plants That Can Be Planted in Pitcher Plant Soil
If you want to add some variety to your outdoor pitcher plant garden, there are a few other plants that also do well in the same soil mix that pitcher plants require. Here are some good companions for pitcher plants to add visual interest and beauty.
- Giant rhubarb: Giant rhubarb is very tolerant of soil acidity levels but prefers acidic soil like pitcher plants do.
- Flag iris. Flag irises grow well in moist, well-drained soil and prefer acidic soil mixes.
- Venus fly traps. Because they live in similar habitats, Venus fly traps do well in the same areas that pitcher plants grow in.
- Jack-in-the-pulpit. Like giant rhubarb, jack-in-the-pulpit is very tolerant of soil acidity, but does well in the same soil type as pitcher plants.
- St. John’s wort. St. John’s wort is a bog plant that does well in a variety of soils and can even be used for medicinal purposes if you have any would-be herbalists in the house.
Pitcher Plant Soil and Winter Dormancy
One thing to take into consideration for planting outdoor pitcher plants is that pitcher plants require a period of winter dormancy between November and February in order to thrive, so if you live in the tropical South where your winters are mild, your pitcher plants may not do well.
If you want to plant outdoor pitcher plants in areas that do not get cold enough in the winter to sustain them, you can dig up your pitcher plants, brush the dirt off them, put them in plastic storage bags, and refrigerate them through the winter months to be replanted in the spring.
In areas where you do get a cold winter and are cultivating pitcher plants outdoors, you can cover your dormant pitcher plants with three inches of pine needle mulch. This will both protect the dormant plants from freezing temperatures and leech needed acid into the soil to amend it.
Pitcher Plants Are Easy to Care for If You Get Their Soil Right
Pitcher plants are a beautiful and unusual addition to your houseplant collection or your home garden, provided you take the time to learn a little bit about their horticulture and the best ways to keep them happy and healthy.
While pitcher plants do not derive many of their nutrients for the soil, the moisture level, acidity, and composition of the soil are still crucial to make sure your pitcher plants can look their best.