Polypodium

These are leaf-losing (deciduous) and hardy evergreen Ferns that are found in many parts of the world including tropical, semitropical and temperate areas. Some may be cultivated in hothouses and some in cool greenhouses. The bright green leaves are thin and tough and may vary from only a few inches to 6 feet long. They may be pinnate (feathery-divided once), bipinnate (divided twice), or simple (undivided).

POTTING - Hothouse and Greenhouse kinds: Those grown in the hothouse require a minimum winter temperature of 55 degrees and those grown in a cool greenhouse require one that is 45 degrees. The best compost to use consists of equal parts of loam, peat, leaf mold and sand, with a bit of crushed charcoal added. Repotting should be done between February and April, or as soon as new growth begins. The plants should be removed from their pots and the roots examined. Those that have a healthy root system can be repotted into larger pots; those that haven't yet filled their pots should be placed back in their old pots until later in the season or following spring. If the soil has rotted because of insufficient drainage and the roots have decayed, every bit of soil needs to be washed off the roots in a pail of water that is room temperature. The roots should be cut back to the healthy sections and then replanted in pots just large enough to hold them without cramping. When repotting healthy specimens, the old crocks and loose soil should be removed and the new pots should have a layer of crocks that are covered with rough siftings from the compost or coarse leaves. Press the new compost firmly with your fingers. After potting, the soil shouldn't be watered until it is fairly dry, then it's completely soaked. Repeat this procedure until they have grown a sufficient amount of roots and when they have, keep the soil moist. Towards autumn, when growth has ceased, the water supply is decreased and during the winter the soil is only watered when it becomes moderately dry. The Polypodiums that lose their leaves in the winter should only be watered occasionally, just enough to keep the roots from withering. A humid atmosphere should be maintained at all times by wetting the benches, walls and floors, although less humidity is necessary in the winter especially in very cold winter. Several kinds can be grown in hanging baskets, such as P. subauriculatum. Line the baskets with moss and fill them with compost. Plant the Ferns in the baskets and hang them. Water them as you would if they were in pots. The best way to water them is by setting them in a pail of water.

Hardy kinds: These Ferns need a shaded or partially shaded spot and they are great for growing in rock and wild gardens, in shaded borders, in sheltered nooks in shrubbery, or in specially prepared beds. The best soil consists of equal parts of loam (or good garden soil) and leaf mold. Planting should be done in the fall or spring and the soil needs to be kept moist. A layer of leaf mold can be spread over the soil in March or April to help hold moisture in. The fronds of the deciduous Polypodiums shouldn't be removed until the spring because they protect the crowns.

Propagation

As soon as the spores are ripe, they can be sown. To tell if they are ripe, a frond is plucked and placed in a paper bag. This is hung in a room for 24 hours. The spores that fall to the bottom of the bag are ready for sowing. Small pots are filled half way with crocks, which in turn are covered with rough siftings from the compost. Fill the rest of the pot with finely sifted compost and moisten it by setting the pot in a pail of water. Scatter the spores thinly on top of the soil. A pinch of spores is plenty enough for a 5-inch pot. After they are sown do not apply any water. Keep the soil moist by setting the pot in a saucer of water and cover it with a pane of glass. As soon as they are big enough to handle, they can be pricked out in little clusters and planted an inch apart in a deep seed pan filled with finely sifted compost. Moisten the soil and lay a pane of glass over them for a few days so they can become established. When they're large enough to be potted separately, do so in 2-inch pots and later on in larger pots. The hothouse kinds should be raised in nighttime temperatures of 65-70 degrees and those belonging in a cool greenhouse should have 50- to 60-degree temperatures. Division is also another means to increase these Ferns, especially the crested and tessellated varieties. Those grown in a greenhouse are divided at potting time. When they're taken out of their pots and the crocks and loose soil are removed from their roots, they can be divided into several pieces, each containing a portion of the crown or rhizome, roots and a couple of fronds. They are each potted in a pot just large enough to hold the roots without cramping. The procedure for the hardy kinds is the same way and it is done in April. The pieces are planted directly in their permanent spots.

P. pectinatum

VARIETIES

• Hothouse varieties:
  P. albido-squamatum;
  P. loriceum;
  P. pectinatum;
  P. quercifolium (Oak-leaved Fern);
  P. verrucosum.
• Cool greenhouse varieties:
  P. aureum;
  P. aureum Mandaianum;
  P. Billardieri;
  P. pustulatum;
  P. subauriculatum;
  P. subauriculatum Knightiae.
• Hardy varieties:
  P. vulgare and its varieties bifidum, cristatum, elegantissimum, hesperium, occidentale and trichomanoides;
  P.polypodioides.