A: This is one of the most common questions I get every February. Gardenias, like azaleas, would need to be pruned after they have finished flowering, which will be sometime late spring or early summer. The best management practice for most any flowering plant is to prune directly after flowering. If they are pruned now in late winter, then we will reduce the number of flowers produce as the buds for flowering have already been formed.
Gardenias and azaleas really require very little pruning except to improve their shape and/or remove broken or diseased stems. It is possible to prune azaleas or gardenias to increase flower production but keep the removal of stems to a minimum. Selectively prune a stem by hand rather than use a motorized pruning utensil. Hand prune the stems selectively by cutting back to a bud and be sure the stems are cut at a proper angle. Cuts should be made about ¼ inch above the bud. It is also best to prune the shrubs so they are smaller on the top and larger on the bottom to allow for the best exposure to sunlight.
Remember, gardenias like well-drained, acid, organic soils. It is important not to water them as often as we do lawns. Avoid using heavy rock mulch around the root area as this will cause compacted soil. Consider using pine straw or pine bark as a mulch. Leave an area about 12-18 inches around the trunk with nothing but soil and air, which is an excellent practice for any tree or shrub. I know everyone is eager to get out and prune their perennials but it is best to wait a little longer until we are certain the fear of freezing temperatures is truly over.