Ferns are special plants. Fossil records show that they date back to the Paleozoic era, 400 million years ago. Ferns have been around for millions of years, and they’ve adapted to nearly every climate and environment on Earth. They flourish in alpine areas and deserts of the world, in ponds and lakes, on the ground and high in trees, and in temperate and tropical climates.
Many plant lovers shy away from ferns, considering them hard to grow. But growing ferns can be simple if you follow a few basic guidelines.
How Humidity Affects Ferns
Ferns must have humidity, which is usually lacking in modern homes.
- To humidify your ferns, fill a saucer or tray half full with gravel. Let the plant pot sit on top of the gravel.
- Keep a little water in the gravel at all times, but don’t let the water level reach high enough to touch the bottom of the pot.
- If your potted fern grows in a decorative planter, you can stuff moist sphagnum moss between the pots and remoisten as needed.
Ferns do best in areas not warmer than 72 degrees F. Temperatures from 60 to 65 are ideal. Keep ferns away from drafts.
- If possible, use distilled or rainwater. If you must use tap water, let it stand a few hours before applying.
- Don’t pour water over the fern foliage. This applies to ferns in hanging baskets, as well.
- Don’t let water touch the foliage if you water your hanging basket fern by immersing it in water.
- Fern baskets hanging outside should be in complete shade, protected from wind.
- Good drainage is crucial because the soil should be kept moist.
Light & Ferns
Although we associate ferns with shady, moist gardens, they still need adequate light indoors.
- Indoor ferns grow best in bright, indirect light.
- Place your ferns in bright windows. A window with an eastern exposure is best; sheer curtains can veil south and west windows for fern culture.
- Don’t move your plants too far from these windows (no more than 2 to 3 feet away), as this reduces the light significantly.
If necessary, use insecticidal soap, a non-chemical insect control. Be sure to follow the label directions for mixing.
Ferns are grouped by their natural habitat. We classify them as epiphytic (growing in trees), terrestrial (growing in soil), or aquatic (growing in water).
Epiphytic ferns need coarse soil that allows fast and thorough drainage. It should be rich in organic leaf mold, sphagnum moss, or peat moss. Epiphytic ferns can be planted in hanging baskets or pots with the proper soil mix. They can also be mounted on logs, slabs, plaques or mats.
Staghorn and the Polypodium “footed ferns” are examples of epiphytic ferns.
Terrestrial ferns, the largest group of ferns, will grow in normal potting soils. Their mix should contain peat moss, perlite for added drainage, and maybe some sand for added weight. Terrestrial ferns can be planted in hanging baskets, pots, or tubs.
Boston ferns and their many varieties and Maidenhair ferns are examples of terrestrial ferns.
Aquatic ferns are usually found floating in or at the edges of ponds and lakes. They’re suitable for outdoor koi ponds, aquaria, and patio container water gardens. The water clover, Marsilea Quadrifolia, is a good example of an aquatic fern that can adapt to soil. The widespread mosquito fern, Azolla caroliniana, which sometimes covers hundreds of square feet as a single colony, is an example of a free-floating water fern.
Potted ferns should be fed monthly from March to October. Ferns growing in hanging baskets should be fed every two weeks.
Organic fertilizers, fish emulsion being one of the best, won’t burn your ferns. Water-soluble fertilizers also give superior results if you precisely follow the manufacturer’s directions.
Fertilizer burns are more likely to occur with ferns in hanging baskets because the roots are close to the fertilizer granules. Dilute the fertilizer and apply it to the soil, not the foliage.
Re-potting & Divisions
Ferns need repotting every one to three years, depending on the size of the pot and the rate at which your fern grows.
Ferns also benefit from division every three to five years. You can do this in the spring or fall.
To re-pot, remove the fern from its pot, shake away excess soil, and cut away any dead or damaged roots with a sharp knife, taking care not to injure the crown.
Then replant it in a slightly larger pot than the original one. Add soil and press it firmly around the roots. Water thoroughly after re-potting.
The best time for division is early spring when new growth begins. Always use sterile potting mix when repotting or dividing ferns.