The days are lengthening and the temperature is perceptibly slightly warmer. We decided to plant a tree fern into the open ground in a sheltered, shady spot. Our Dicksonia antarctica resembled a log with hardly any roots and no fronds. This poor specimen had been in a very windy position and one day, we found it had been blown over. A lovely Gesneriad, Asteranthera ovata, a Chilean plant with bright red, tubular flowers, had taken root up its trunk and we carefully transplanted this by binding the plant’s root to the tree fern trunk.
We dug a hole about a foot deep and then setting the trunk upright, hammered in four square pegs to stop the bole wobbling in the wind and breaking any roots which may emanate from it. Then we added some general-purpose compost and then some soil to top up. With the fern now solidly upright, we set up a hose and thoroughly wet the trunk. We will give it a thorough wetting each week until all the new fronds are completely unfurled. Tree ferns produce their roots in their crown, immediately under the croziers. They travel down the inside of the fibrous trunk where it is 100% relative humidity. Wetting the trunk on a regular basis, prevents the trunk’s interior from drying out, so the roots can continue growing. This time next year, we could remove the four pegs, as the tree fern will have a collar of fibrous roots established to stabilize itself. Once the tree fern has unfurled all its croziers, anywhere from a dozen to 16 new fronds, foliar feeding can begin to form next year’s crop of croziers. All ferns respond really well to half strength liquid seaweed extract applied to the foliage monthly. This will make a huge difference to their general health and vigour.
Many of our cuttings were potted into 9cm square liners and now, many have roots protruding from their drainage holes. This is the time to shift them up a couple of pot sizes and once they have settled, those which we hope to train into standards will receive their first high Nitrogen feed of the year to push growth on and to prevent them running to flower. The pots are turned a quarter turn every day to keep them vertical and as soon as roots are seen emanating from the bottom of these new pots, they will be shifted up a couple of pot sizes again. The aim is to allow no impediment to the plant’s vigorous development. In the autumn, they will be kept close in a slightly heated glasshouse all winter. The idea is to prevent the sap retrenching down to the roots. This keeps the plant’s transport vessels, the xylem and phloem, expanded and alive, so that by the following autumn, the sap will not fully retrench from the crown and that when the sap rises again in the following spring, the standard will break up in the head rather than send up shoots from the roots.