UNITED STATES—Ready or not, it will be autumn in just a few days. Formal hedges can be shorn one last time if they need it. They will not grow much until spring. Actually, photinia and the various pittosporums should not be shorn much later than now if they exhibit any dieback. Some of the diseases that cause dieback are more likely to infest freshly cut stems during rainy weather. Citrus and plants that can be sensitive to frost should not be pruned later, since pruning can stimulate new growth that will be more sensitive.
For the same reason, most plants should not need fertilizer as their growth naturally slows. Through winter, new growth is likely to be damaged by wind or discolored by nutrient deficiency. Even if the nutrients that keep foliage green prior to autumn are in the soil, some are less soluble at cooler temperatures. It is really best to allow plants to get some rest. Only plants that are active through winter, like cool season vegetables, cool season annuals, and some cool season turf, will benefit from fertilizer.
However, some plants that are generally dormant through cool winter weather will not be completely inactive. Many plants, particularly tough evergreen perennials like lily-of-the-Nile, African iris and many ferns, continue to disperse their roots to be ready to sustain new foliar growth next spring. This is one of the reasons why autumn is the best time to get such plants into the garden, even if they do not seem to do much until spring. Autumn is also a good time to seed lawns or install sod.
The other reason for planting in autumn is that, as the weather gets cooler and rainy, new plants that have not yet dispersed their roots will be less likely to dry out than they would be in spring or summer. Some bulbs that will soon be available in nurseries want to be in the garden before winter because a bit of cold weather promotes healthier bloom.
highlight: gardenia
It seems that everyone who has ever experienced the seductive yet powerful fragrance of gardenia, Gardenia jasminoides, wants to grow it, but very few actually can. Gardenias like warmth, but prefer more humidity than they get here, which is why they seem to be happier in partial shade, in atriums, or in urns that can be moved out of harsh exposure during summer. In such sheltered spots, aphid, scale and sometimes whitefly can be problematic.
Gardenias want their own space, where their roots will not be bothered by excavation or roots of more aggressive plants. They do not even want annuals around them, because annuals need such regular cultivation. Docile ground cover plants or simple mulch is best. Gardenias like rich soil and acid fertilizer or fish emulsion to be applied regularly as long as the weather is warm.
The creamy white flowers that fade to French vanilla can seem mundane relative to their alluring fragrance and handsomely glossy foliage. The largest flowers rarely get to three inches wide. ‘Mystery’, which can slowly get four feet tall, is the most familiar cultivar, even though it does not bloom so much after spring. ‘Veitchii’, which can eventually get three feet tall and twice as wide, has small inch-wide flowers, but is still blooming. Modern cultivars bloom just as late, but with larger flowers.
By Tony Tomeo
