Philodendrons are examples of tropical jungle plants that must grow fast to get to and stay on top of the forest canopy. If they grew as slowly as climbing roses, they would be overwhelmed and shaded out by other, more aggressive plants. Philodendrons are so well adapted to this sort of competition that the types with large leaves employ long petioles (leaf stems) to push their emerging leaves through foliage of other plants. Once through, the large leaves unfurl over any other plants below.

Bear's breech (Acanthus mollis) is an example of a plant that grows quickly to more efficiently exploit a brief growing season. New plants become established and grow quite large even during their first year. The foliage then dies in winter. The new foliage that emerges suddenly in spring can be impressively lush and abundant, and surrounded by several new pups (side-shoots). During the second year, the pups can grow as rapidly as the parent plant did the previous summer!

Birches are a classic pioneer species. After a birch habitat has burned, birches are the first trees to start growing. They grow quickly and profusely; they will eventually be displaced by slower but more competitive oaks and maples. Birches will eventually become less common, but not quite completely absent. There will always be at least a few to keep the forest floor littered with seed, in anticipation of the next fire.

Fast growth is both the one common asset and the one common flaw shared by many fast-growing plants. They grow rapidly enough to function as intended in the garden within a few years or less. However, they just as quickly develop problems that slower-growing plants need many years to develop. For example, a shamel ash tree will provide shade before it is even 5 years old, but can develop structural problems before it is 10.

Many fast-growing plants are aggressive, and some have short life spans. Lombardy poplars grow so large so quickly that within only a few years, their root buttresses can displace concrete pavement, their roots can deprive other plants and their canopies can shade out lawns. After being such a bully in the garden for about 25 years, Lombardy poplars suddenly die, leaving a large void where everything else was displaced!

Poplars, alders, willows, many ash, most eucalypti, most acacias, silver maple and Leyland cypress are some of the fastest growing trees. Silver maple is actually a nice shade tree for large areas. Leyland cypress is a good evergreen screen. However, poplars and willows are too aggressive for refined landscapes. Philodendron (selloum), New Zealand flax and bear's breech are some of the fastest growing perennials. Oleander, photinia and glossy privet are some of the faster shrubbery.

Flower of the Week: Yarrow

Although Achillea millefolium is known as "common" yarrow, there is nothing common about the flower colors that have been developed during recent years. This traditionally white flower now blooms with various shades of yellow, orange, red and pink. The individually small flowers are packed tightly onto flat rounded clusters held above foliage on stems as tall as 3 feet. Bloom is mostly during summer and early autumn, but may begin in spring. The finely textured and slightly aromatic leaves can be green or grayish green.

Most types of yarrow require only minimal care. They appreciate full sun and moderate watering. They are quite tolerant of draught when established. Removal of faded flower stems promotes healthier subsequent bloom. Large clumps can be cut back and divided in winter.

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