Houseplant Handbook. David Squire

      Air Layering

      Air layering is used to increase large, woody houseplants such as Ficus elastica (Rubber Plant) that have grown tall, with bare woody stems. Best undertaken in early and midsummer, it involves partially severing a stem just below the lowest leaf and encouraging it to develop roots.

      Step-by-Step: Air Layering a Rubber Plant

      1 Choose a healthy plant that is bare of leaves on the lower part of its stem. The top 1 ½ft (45cm) of the plant should have healthy leaves.

      2 Use a sharp knife to make an upward-slanting cut, two-thirds through the stem and 3–4in (7.5–10cm) below the lowest leaf. Take care that the top part does not snap off.

      3 Insert a matchstick into the cut to hold it open. Trim off its ends and use a small brush to coat the cut surfaces with a hormone rooting powder.

      4 Wind a piece of clear polythene film, about 9in (23cm) wide and 12in (30cm) long, around the stem, and secure its base about 2in (5cm) below the cut.

      5 Fill the tube formed by the polythene with moist peat. Pack it to about 3in (7.5cm) below the tube’s top. Tie the top around the stem with string.

      6 Keep the compost in the pot moist so the plant continues to grow. Six to eight weeks later you will see through the polythene that roots have formed.

      7 Hold the top of the plant and sever the stem directly below the polythene. Carefully remove the film.

      8 Immediately place the plant into potting compost in a clean pot. Dribble compost around the roots and carefully pack it. Support the stem until the plant is established. Do not throw away the old plant. Instead, cut it to about 9in (23cm) high and place in gentle warmth, about 54–64°F (12–18°C). Young shoots will develop from the stem to form a multistemmed plant.

      Houseplants from Plantlets

      A few houseplants develop small plantlets along or at the edges of leaves; these can be removed and encouraged to produce roots and develop into separate plants.

      Step-by-Step: Plants with Plantlets

      1 Choose a healthy mother plant (such as the Kalanchoe daigremontiana) and gently detach plantlets growing along a leaf’s edges.

      2 Fill a pot that is 3in (7.5cm) wide with compost and pack it to about ½in (12mm) below the rim. Space out plantlets on the surface and slightly press them into the compost. Gently water the plantlets from above, taking care not to disturb them.

      3 When rooted and growing well, transfer them to individual small pots. When potting rooted plantlets of Kalanchoe delagoensis, put three plants in each pot.

      Houseplants from Runners

      Some houseplants produce plantlets at the ends of long, runner-like stems, perhaps the best-known example being Chlorophytum comosum (Spider Plant). Although this can be performed throughout the year, late spring to late summer is best.

      Step-by-Step: Increasing a Spider Plant

      1 Water the compost in the mother plant and select several long, healthy stems, each with a healthy plantlet at its end. Fill several pots with compost and pack it to ½in (12mm) below the rim. Position a plantlet in the compost and use U-shaped pieces of wire to hold it in place. Lightly water the compost and stand the mother plant and the pots with pegged-down plantlets in a large seed tray. This makes it easy to move them as a unit.

      2 When new shoots develop from the plantlet, sever the runner close to the plantlet. Also cut off the stem close to the mother plant’s base.