Willow Glen Resident

Gardening

Shade Lovers: Fibrous begonias are popular bedding plants that bloom in shades of pink, red and white. They grow best in loose, rich soil with regular irrigation and occasional fertilization.

Horticulturist growing plants on his 'concrete slab' garden

By Tony Tomeo

It is so ironic I am the only horticulturist in the neighborhood, and one of only a few in the entire town, but I have more pavement in the garden than anyone else does. It is good pavement though--great for a basketball court, parking lot, space shuttle launch pad or whatever I want to use a vast concrete slab for. Unfortunately, one of the few things it is not good for is gardening. In order to make the pavement conducive to gardening without removing it, everything that grows on it must be containerized.

The main advantage to containerized plants is portability. Flowering plants with short bloom cycles can be moved to more prominent places in the garden when they are at their best, and then moved elsewhere when finished. During hot summer weather or cold winter weather, plants that might be damaged by exposure can be moved to more sheltered locations. Some people simply like to be able to move certain plants around to modify their gardens.

Large pots or urns are useful to elevate low plants. Some bedding plants that are nice on the ground, like fibrous begonia and petunia, are even more pleasing if their flowers or foliar qualities can be seen a bit closer. Certain creeping or sprawling plants likewise look better if they can spill out over the edge of a large pot, just as some of the smaller ones, such as fuchsia and verbena, do from hanging baskets.

The disadvantages to containerized plants are confinement and lack of root insulation. Large woody plants cannot disperse their roots nearly as far as they would if they were planted in the garden. They quickly use up all the moisture within their container and become desiccated because their roots do not extend into anything with more moisture. Small plants and annuals may need considerably less water than they would in the garden, but larger plants may need more.

Containerized drought-tolerant plants are often more sensitive to desiccation than are those that like more water. Because they do not need as much water as frequently, they are sometimes neglected. With their naturally broad and deeply dispersed roots, this would not be a problem in the garden. However, if confined without extensive roots, they can dry out as soon as their soil does. Larger or overgrown plants will, of course, need more water because they have so much more foliar surface area (leaves) from which moisture evaporates.

Because containers are exposed on all sides, the temperature of the soil within fluctuates with the weather, and can get uncomfortably warm. Parts of containers that are exposed to sunlight absorb additional radiant heat and transfer it to internal soil. Plants in vinyl (plastic) pots, particularly the darkly colored ones, are more vulnerable than are those in thick clay pots. I like to grow certain large items in black vinyl nursery cans, surrounding them with smaller plants in clay pots that both obscure and shade the vinyl. Freezing in winter fortunately is not much of concern locally.

Flower of the Week: Fibrous begonia

Whether cool season annuals in warm climates, or warm season annuals in cool climates, fibrous begonias, which are also known as bedding, wax or semperflorens begonias, are actually perennials that can survive through their off-season to recover when the weather is more favorable. The Santa Clara Valley is neither too hot nor too cold for them, so they look only a bit singed after the warmest summer weather, and sometimes freeze only during the coolest winter weather. Partly shaded plants should not burn and are less likely to freeze (if under trees or eaves), but are not quite as compact nor bloom quite as well as more exposed plants.

Begonias like rich, loose soil, and appreciate occasional application of fertilizer. They are easy to propagate by stem or leaf cuttings, or by division of larger clumps, even though some of the parts divided may lack roots. The most popular varieties of fibrous begonias are about 6 inches tall. Larger varieties can be as tall as 10 inches. Their white, pink or red flowers are most profuse during warm weather, and can continue to bloom sporadically through winter. Foliage may be green, bronze, reddish or even variegated.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.