First steps in setting up an irrigation system

By Christina Muller  UC Master Gardener

What should I know before setting up an irrigation system for my garden?  Katie in SLO

Living as we do in a Mediterranean climate, water is a valuable resource and for some people it may be the largest annual expenditure in the garden.  It makes sense to conserve and apply water as judiciously as possible.  A well-planned irrigation system can accomplish this.

It is important to first study the site.  Consider your soil type since water will infiltrate at varying rates.  For instance, sandy soils hold less water than clay and need more frequent irrigation.  Know which plants are drought tolerant as they may be able to survive on seasonal rains, thus requiring no additional irrigation.  Take into account the root depth of plants; annuals may not need to be watered as deeply as those with longer roots.  Steep sites may benefit from terracing to slow water enough that it soaks into the soil instead of running downhill.  Finally, know that sun, shade, temperature, humidity, and wind impact the amount of water that plants require.

A common concern for gardeners is how to effectively irrigate their lawns.  A well-designed sprinkler system will water evenly without overspray onto sidewalks or driveways.  The “Lawn Watering Guide for California” is a free UC publication athttp://anrcatalog.ucdavis.edu/pdf/8044.pdf .  Gardeners can use this to determine the output of their sprinklers and learn the suggested frequency and duration to water each month of the year.

Another helpful resource is the San Luis Obispo County Water-Wise Landscaping site athttp://www.slowaterwiselandscaping.com/Garden-Resources/ .   In addition to information on irrigation systems, gardeners can learn more about water conservation by mulching and grouping plants with similar needs.

To learn more about setting up a system and to see a demonstration with various irrigation components, attend the Advice to Grow By seminar at the Garden of the Seven Sisters, 2156 Sierra Way, San Luis Obispo, on Saturday, May 18 from 10 am to noon.

I notice moths flying around my oak tree, should I be concerned?  Ann M.  Atascadero

By Andrea  Peck  Master Gardener

The small grey or tan moths that you see flitting about your oak tree are likely the oak moth.  About ½ inch in length with pronounced wing veins, the moths are commonly seen during the fall and summer months. Two to three dozen tiny white eggs are laid on the underside of the leaves; eggs turn pink to brown before hatching. The larva that emerges is known as the California oakworm.

The oakworm, unlike its name, is actually a caterpillar. This small, yellow-green caterpillar has a notably large brown head and dark stripes that run along its sides.  Caterpillars extend to about 1 inch when fully grown. As the oakworm grows, it feeds on the oak tree, silently munching through the leaves. When populations are high, defoliation may occur and can be visually alarming. During warm, dry winters, caterpillars thrive.  Drought conditions may precipitate a third  generation of breeding, feeding and metamorphosis. Mass “balding” throughout neighborhoods and groves may lead to the generally erroneous thinking that “something must be done to save the trees!”

The good news is that action is generally not required. The healthy oak can withstand quite a bit of feeding from these tiny gnawers. On occasion, the oakworm will abandon a defoliated tree in search of other food sources. These tiny herds have been known to scale walls, cross lawns and even sneak inside homes to be found hanging from draperies. Not to worry, these hapless creatures do no harm. When food is scarce, the oakworm may rampage nearby plants.  Despite heavy feasting and the subsequent wear and tear on the plant, the oakworm cannot mature on non-oak species and therefore, seldom poses a permanent threat.

Management of the oak moth begins with proper care of the tree. Pesticide use is generally discouraged even when masses of oak moths appear overwhelming. A healthy tree will naturally attract animal and insect hunters. Birds, spiders and predatory insects all love the sight of your tree brimming with their next meal. Your best bet is to pull up a seat and enjoy the show.

May is the time to prepare for your summer garden!

Terri Sonleitner Law,  UC Master Gardener

 I love the blooms in my garden now, but I know summer is just around the corner. What things should I be doing in my garden in May to prepare for summer?  Charla, Atascadero.

 Gardeners all look forward to May. Plant growth is at its peak, everything seems to be in bloom, and all heat loving summer vegetables can be planted in the vegetable garden. May is a great time to be outside enjoying the garden, but it’s also the time to prepare the yard and garden for summer.

* Prune winter and spring flowering vines, bushes and trees after they complete their bloom cycles. Pinch back chrysanthemums to about 12 inches for flowers with shorter stems in the fall.

* Remove spent flowers and deadhead roses regularly to encourage further blooms. Feed your roses every 6 weeks for continuous blooms.

* After mid-May sow seeds outdoors for warm season vegetables, including corn, cucumbers, green beans, melons, pumpkins, winter and summer squash. After mid-May plant out seedlings of eggplant, tomatoes and peppers. In the North County, you may want to wait to plant out heat-loving vegetables until the latter part of May when the soil has warmed.

* In the herb garden, pinch back the tops of herbs frequently for continual production. Harvest herbs in the morning for best flavor.

* If you didn’t fertilize your lawn in April, do so now. Dethatch your lawn if it needs it.

* Deeply water trees and shrubs through a soaker hose or drip system. A thorough soaking each week, or twice per month, uses less water than frequent lighter applications. Check sprinkler timers, sprinkler heads and drip emitters, and be sure to apply water during the morning hours.

* Above all, enjoy your time in the garden! May is also a great time to plan a visit to an arboretum, or to take a garden tour. It’s inspiring to see landscapes while they are at their very best and during their peak bloom period.