Saratoga News

Gardening

California blue sage is a tall, graceful evergreen shrub whose leaves and flowers are both fragrant. This drought-tolerant sage is also available in several popular hybrids, including 'Pozo Blue' and 'Winifred Gilman.'

The rainy season has ended, so it's time to water the lawn

By Tony Tomeo

Getting back into the habit of watering the lawn and garden in the spring seems like much more work than it was last year. Yet, it is the same routine. The rain stops. Weather gets warm. Everything in the garden starts to grow and get more demanding. Plants that were getting more rain than they could use, even if they were not dormant, suddenly want water.

These same plants also become susceptible to many diseases and insect infestations that were not a concern in winter. Like the plants, bacterial and fungal pathogens (organisms associated with disease) become active as weather gets warmer, particularly if warm weather is mixed with rainy weather for a long time. Such weather patterns mix the two things that these pathogens like most: moisture and warmth.

The constantly rainy winter weather provided plenty of moisture, but was too cool. Hot summer weather later will provide plenty of warmth, but lacks moisture and humidity. This is why peach leaf curl and anthracnose are so troublesome as new foliage appears in spring. Peach leaf curl affects peaches, nectarines, plums, almonds and related stonefruit.

Anthracnose has been a problem among ash and sycamore trees. Both diseases look disastrous, but as weather gets warmer and drier, new replacement foliage grows faster than it can be ruined by the slowing anthracnose. Many insect pathogens behave similarly, but unfortunately most stay active through summer.

With their preferred combination of moisture and warmth that comes naturally with spring weather, these diseases and insect pests certainly do not need any help infesting. Yet, they often get it. Long after the rain has stopped, watering the garden provides the moisture these pathogens crave. This is why timing of watering, both in frequency and in duration, is so important.

Most of the problems I find in gardens and landscapes are caused by excessive irrigation. If watering is too frequent, it goes into the soil about as fast as it can drain out. If duration is too long, more water goes into the soil than can drain out in the time between watering. Either way, saturation is maintained, causing root rot, molds or other fungal diseases. This moisture also increases ambient humidity, causing foliar diseases such as powdery mildew and rust.

Plants and lawns should be watered only as much as necessary. Lawns that are constantly soggy or mossy are too wet. Tree or shrub roots at the surface of the soil indicate that lower strata are too wet for the roots to live in. Plants with shallow fibrous roots, such as lawns and annual flowers, need frequent watering, but do not need much water. Trees like a bit more water, but not very often.

Unfortunately, frequency and duration of watering can only be determined by trial and error. There are simply too many variables to consider, like plant and soil types, and exposure. Watering should be done in the morning so that the area can dry during the day, and not be humid overnight.

Flower of the Week: California blue sage

Although quite common in the hills of Southern California, California blue sage, Salvia clevelandii, is not very common among local gardens. It enjoys the sunny and warm climate here, but does not like the frequent watering that most gardens get. It is more tolerant of moisture if drainage is very good. However, with less water, it can be happy in inferior or even dense soil. (Dense soil does not drain well.) This makes it a good choice for areas of the garden that are too dry and too exposed for other plants.

Most varieties of California blue sage are wider than tall when mature--about 6 feet wide and 4 feet tall. The grayish evergreen foliage is remarkably aromatic and actually makes a good tea. The individual wrinkly, serrate leaves are about 2 inches long. In spring or early summer, delicate whorls of fragrant, inch-long flowers bloom on stems as tall as 2 feet. (Whorls are radial arrangements of flowers or leaves.) Removal of fading flower spikes promotes continuing bloom. Flowers are traditionally very pale purple to light blue, but modern varieties are more brightly colored. The "Pozo Blue" hybrid seems to be especially popular.

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