Columnar apples are apple trees (Malthus spp.) which have been bred to produce no side-branches. The fruit and leaves protrude solely from a single vertical main stem. Columnar apples are a modified dwarf apple tree stock, growing 8 to 12 feet tall depending on the variety, though they can be pruned to keep the height significantly less than this to suit your landscape needs. Grow columnar apples in a large container to add a beauty to your deck or balcony or a handy fresh-picked snack just outside your door.
Drop terracotta flower pots on the ground from a height to smash them; place the shattered remnants of 1 to 2 6-inch pots in the bottom of each 15 gallon decorative container for drainage. If a single large curved piece of terra cotta remains, place it upside down over the main drainage hole of the planter.
Mix one part well-aged compost with two parts potting medium. Moisten with rainwater until it is damp and crumbly. Fill the large decorative pots about two-thirds of the way with this mixture. Form the potting mixture into a cone pointing upward in the center of the pot.
Remove the columnar apple tree from its nursery or shipping container. Hold the stem with one hand and lower it into the pot, gently spreading the roots over the cone of potting material with the other hand. Continuing to hold the stem upright, fill in over the roots with potting mixture until enough soil is in the pot to hold the columnar apple tree upright. Fill to the rim and water lightly. Add soil after the potting mix has settled in a few days to bring the soil level just to the base of the columnar apple stem.
Set each decorative pot on three bricks arranged to hold the pot stable and level while allowing good drainage. Place the pots within 6 to 10 feet of one another to maximize pollination and fruit production, in a full-sun location.
Water the columnar apples frequently in dry weather, adding liquid fish emulsion fertilizer to the watering once a month.
Move the pots to a sheltered location in winter, outdoors or in a garage or basement, where temperatures will remain above a hard freeze but below 45 degrees. Water infrequently through winter dormancy, just enough to keep the soil from drying out. Begin regular watering and return the plants to a sunny outdoor location in spring.