Ferns

Overview:

As a general rule, if you have a partially shaded spot which does not get too dry in the summer you will be able to grow hardy ferns successfully.

Some fern varieties are acid soil or lime tolerant, some will survive in dry shade, but most prefer a moist, well-drained, shady site in humus-rich, neutral to alkaline soil which does not get too dry.

Evergreen ferns are often the most tolerant of dry sunny conditions.

Those that are grown in dry shade will require watering in their first season, and a mulch of organic material to conserve the moisture.

Select evergreen types for winter interest particulurly when covered in hoarfrost, and deciduous types to witness the unfurling of the young crosiers in the spring.

Evergreen ferns pretty much look after themselves, generally the only pruning required is to cut out dead or unsightly fronds, these should be removed before new crosiers appear.

Watering:

Care should be taken when watering.

Water should be directed towards the roots avoiding the fronds and crown as this can encourage rot.

If rot does develop, treat with a general fungicide.

Do not let the plant dry out during the winter as this is a frequent cause of failure, rather than the cold.

To avoid containerised plants drying out stand the pot in a shallow tray of water and keep this topped up, but not in winter.

During winter it is better to prop the container on bricks to allow any excess rainwater to drain off.

Feeding:

Feed containerised plants between March and September with a balanced liquid fertiliser.

Rake in a granular balanced fertiliser around the base of plants being grown in the border circa Week 15.

Pests and Diseases:

Ferns are generally free of pests if planted in the ground, but may suffer from a vine-weevil attack when grown in pots.

New growth may be attacked by slugs / snails in spring.

Some of the denser growing ferns may get occasional leaf spot.

Thinning out and removing dead fronds to increase the ventilation around the plant/s should alleviate this problem.

Environment:

Ferns will grow quite satisfactorily indoors providing they can be kept in a humid position in a warm moist greenhouse.

Another suggestion would be the bathroom.

They like a light position but not full sunshine.

Apply a light spray of water overhead daily.

Cultivation:

Week 14:

Tidy up indoor ferns, repot those that have become pot-bound or very straggly.

To repot, cut back the top growth with scissors, taking care to avoid damaging new fronds emerging from crown.

Carefully tease away old compost and cut off dead roots, repot into a container of similar size using well-drained compost.

Divide large congested plants, setting each division in a pot of sufficient size to take roots.

Remove and pot up fern offsets.

Vegetative propagation should be used to increase named cultivars as few ferns breed true, plus some can be sterile.

Week 20:

Ferns can be propagated by sowing spores, providing strict hygiene is observed.

Very few spore-producing ferns breed true.

To locate spores look for small heaps or lines on the underside of mature fronds.

With some varieties they may be located at the apex of the frond.

Unripe spores tend to be pale green, turning deep brown as they ripen.

To collect the spores place a small piece of spore-bearing frond in a dry paper bag or envelope and keep for two / three days in a warm, dry place.

Spores will settle in the bottom as a dust-like brown, yellow or black powder.

Preparation:

Fill 70mm (3”) pots with finely sifted 50-50 mix of seed compost and sharp/silver sand.

Place a disc of newspaper on the surface of the pot and pour boiling water over the compost, to kill any stray fungal, moss or fern spores contained within the mixture.

Allow the compost to thoroughly cool before sowing the spores.

When sufficiently cooled, sprinkle the spores thinly over the soil surface and immediately cover the pot with a layer of clear polythene or cling film, secured in place with string or an elastic band.

If propagating different batches, sow each in a different room to avoid cross-contamination.

Place the pot in a cool lightly shaded site indoors for one to two months.

During this period a green film will appear on the surface of the compost.

After about another month or so the first tiny fronds of the new ferns should appear.

When two to three fronds are visible, prick out small clumps new growths into pots of sterilised compost.

Enclose these in a polythene bag in indirect light for a few days, as exposure to dry air at this stage can be fatal.

It may take another six months or so for true fern fronds to appear.

Grow on in a pot for one to two years until the young ferns are large enough to be planted out in the garden.

Winter care:

Dicksonia antarctica may need a little winter protection particularly if they are relatively young.

Circa week 44:

Push straw into the crown of the plant, this helps to keep the crown dry and also insulates the growing point from frost damage.

Circa Week 15:

or when the worst of the frost have passed, remove the straw and the new fronds will soon emerge.

Container plants should either be taken under cover for the winter months or wrapped in bubble wrap to protect the root ball.

The Gardeners Almanac

The place to find out what to do in the garden this week