Ferns

Growing Ferns in Containers

Most ferns will grow successfully in containers provided the containers are placed in an environment suited to that variety. Some varieties, particularly those with sensitive roots systems, are not suited to growing in containers at all.

There are a number of points to remember when choosing ferns to grow in containers. Firstly, there is a greater tendency for temperature to fluctuate in the root zone of a container-grown plant. The roots will almost certainly get hotter on a hot day and cooler on a cold day than they would if they were planted out into the ground. Secondly, the roots are restricted by the volume of the container. A vigorous fern cannot invade and compete for nourishment with neighbouring plants. Thirdly, a container has only a limited supply of nutrients. When you water a container nutrients are leached through and lost. Feeding is thus more important for container plants that for those growing in the ground. Lastly, plants in containers tend to dry out faster than those growing in the ground.

Types of Containers

Baskets: There are basically two types of hanging baskets, the open framework which needs to be lined with sphagnum moss or bark to retain the soil, and the solid basket with small holes for drainage. These solid types should have a little better  than average drainage material in the bottom, e.g. crocks (broken pieces of ceramic material) or stones. Ferns in hanging baskets are more exposed, thus they dry out faster. Plants which can withstand periods of dryness are ideal for baskets, e.g. Nephrolepis. Almost any plant can be grown in a basket, though some will require a lot more attention than others.  Baskets can be grown inside our outside - depending on the type of plant used.

Slabs: Epiphytes are plants which can be grown on other plants. Stag or elk ferns which grow on the trunk or limbs of large trees are examples. Most epiphytes will grow attached to a living plant, a piece of wood (which can be hung on a wall), a slab or some other type of material (provided there is ample organic matter behind the plant for it to feed on). Alternatively, they can be grown in a container though the growing medium needs to be very rich in organic matter).

Some epiphytic ferns will grow equally well as an epiphyte or in normal soil. Epiphytic ferns can be fed by tucking organic material such as fruit or vegetable scraps behind or under the fronds.

Terrariums: Ferns growing inside enclosed transparent containers may be established in bottles, jars, glass domes or other such things. To a large extent, they are insulated from the outside environment, protected from periods of low temperature and low humidity which can be a problem for many ferns. They also protect plants from draughts of cold air.

There are however, disadvantages to growing ferns in terrariums. Diseases can develop more easily and plants can easily become too hot in a terrarium. Never place a terrarium in direct sunlight. Problems with terrariums are generally more likely if the container is sealed - an uncorked bottle or an old aquarium with the lid off will be less likely to have problems with diseases or heat build-up. There are many different ways of providing soil in the bottom of a terrarium. Often a thin layer of charcoal chunks is placed at the bottom to help with the drainage. (Excess water sitting in charcoal is less likely to breed disease). On top of this, sometimes a thin layer of sand or sphagnum moss is used before a layer of potting mix. Sometimes the potting mix is placed straight on top of the charcoal. The potting mix can be any standard fern potting mix, provided it is well-drained and high in organic matter. After placing the soil medium in the terrarium container, you can plant it and water it. Remember though, watering should be sparse for a terrarium. There is nowhere for the excess water to go, and that makes the problem of overwatering something you must watch very carefully. 

A very simple terrarium can be made from an empty 2 litre soft drink bottle. The black cup stuck to the base of the bottle is simply pulled off. The top neck section can be cut off and the bottle inverted, then fitted into the base cup to make a domed cover. There are holes in the base for the cup to drain, but a hole about 1.35cm across should be cut in the top for ventilation. Soil can be put in the black cup and ferns can be planted there along with any other plants e.g. wandering Jew, moss, peperomia, African violet, or ivy. Then the bottle dome is fitted on the top. Other types of plastic bottle can be adapted similarly using pots or bonsai trays as bases.

Pots and Tubs: Growing ferns in tubs and other containers has certain advantages and disadvantages. Above all, plants in tubs are flexible - they make a landscape changeable. Tub plants can be removed out of view when they are sick and returned when they become healthy again. Plants in tubs need more watering and feeding than those in soil, so it is essential that the tub be properly drained. Sufficient holes in the bottom of the tub are needed, and perhaps some large stones for a drainage layer below the soil. Other Containers Non-glazed ceramic containers will drain through the water-absorbent walls and generally require a soil mix which retains more moisture. Glazed ceramic and plastics absorb no moisture at all through the side of the pot, this means more holes are needed in the bottom of the container and they will need a potting mix that has very good drainage characteristics.

Timber containers will rot after a time if not treated regularly with some type of timber preservative such as creosote. Remember that treated pine does not necessarily last for years.

Maintaining Plants in Pots

During warmer weather it can be advantageous to mulch the surface of the pots to prevent water loss. In windy or hot weather, pots of ferns should be kept in a protected position, as either wind or sunlight can speed up the rate of water loss considerably. This is more critical for porous ceramics such as terracotta.

If you are going away during warmer weather, you can prolong the period potted plants don’t need watering by sitting the container in a bucket or pond containing water. The water should not cover more than the bottom quarter of the roots though. The treatment is not a preferred way to treat ferns and should not be done for prolonged periods. Most ferns growing in containers should be re-potted every few years. This is necessary to maintain the health of a fern. The few ferns which are particularly susceptible to root disturbance you should avoid potting-up. If a fern remains in a pot for too many years, its roots can become congested. The tight root ball may repel water so that when you water the plant the water runs down between the side of the pot and the outer edge of the roots without properly wetting the roots in the centre. A plant which has reached this stage has probably depleted most of its nutrients and becomes susceptible to attack by pests and diseases, due to a general low level of health.

When you pot-up a plant, remove some of the old roots and soil. If the plant is very pot-bound you will need to break up the old root ball a lot. You can re-pot it back into the same container it came from, provided around 25% or more of the old soil roots have been removed and replaced with fresh potting mix. If you re-pot into a larger container, you might not need to remove so much of the old soil and roots

 

Who Will Benefit From This Course? 

• Extend your knowledge as a hobbyists
• Become an expert in ferns
• Extend your design opportunities as a garden designer
• Know how to look after ferns in your or other peoples' gardens