If you're wondering what to plant in your yard to reduce water use, cut runoff, rein in the need for air conditioning in summer and heating in winter, plus provide a home for urban wildlife, "trees are the answer."

If you're wondering what to plant in your yard to reduce water use, cut runoff, rein in the need for air conditioning in summer and heating in winter, plus provide a home for urban wildlife, "trees are the answer."

That's the name of a class being taught by Medford city arborist Bill Harrington at the popular, annual "Winter Dreams, Summer Gardens" symposium on Saturday, Nov. 6. It is organized by the Oregon State University Extension Service and the Jackson County Master Gardener Association.

The event, which runs from, 9 a.m. to 4:30 p.m., will be held at the RCC/SOU Higher Education Center in downtown Medford. The cost is $40, which allows you to choose four classes from dozens of offerings. Lunch is included. Registration is at http://extension.oregonstate.edu/sorec/gardening.

Lawns, as we're all becoming painfully aware, take a lot of water and a lot of work, both of which are in short supply during our long, sunny summers.

Trees are the answer, said Harrington during a stroll of Hawthorne Park, because they help save the planet and prevent climate change by storing a lot of carbon, pumping out a lot of oxygen, using a lot less water than lawns, slowing rain runoff to sewers and providing shade, thus reducing the "heat island" of urban hardscape.

In this day of saving resources, you want to research which trees are drought-tolerant — for our practically rainless summers — and also which ones fit your lot size, says Harrington. Most people pick the species first, then try to make it work on a limited lot with a large paved area — often too near structures and wiring, where it will have to be cut back.

You'll want to reverse that process, taking a realistic look at your lot, then find the species that will be happy there and be able to expand its root system two to three times the area beyond the dripline or outer edge of the tree canopy, he notes.

"You need to be realistic about the amount of room you have and not plant a 70-foot tree if your yard only will support a 20-foot tree," he says. "And if you plant it under wires, the utility line people are required by law to prune it. Wires and trees can't coexist peacefully."

Drought-tolerant trees include Vanderwolf pine, golden rain tree, flowering pear, oak, burr oak, Hungarian or Italian oak, paperbark maple and gum tree.

Trees can help with energy conservation (something lawns never thought of doing), by shading the south and west sides of your house, lessening the need for air conditioning by blocking sun with their leaves — but allowing sun during winter when leaves fall off, says Harrington.

In addition, trees transpire and add moisture to your local atmosphere, add value to your house and are proven to boost your mood and speed up healing time if you're sick, he notes.

Once you get trees planted, it's best to resist the temptation to treat them like bushes and start pruning or topping them — a practice that weakens trees and makes them more prone to fall. You also want to research the life span of the tree you're planting. A lot of them, including maple, have the lifespan of a human, and when they get old, they're more susceptible to disease and toppling over.

Harrington unrolls a big aerial photo of downtown Medford, which instantly shocks you with its absence of trees over a large area, leaving a heat-radiating mass of arid concrete, something he plans to remedy with a $50,000 grant to remove a few old dying trees and plant 65 new ones, suited for an "urban forest," which means an area where people outnumber trees.

The Winter Dreams event, now in its 12th year, features a wide spectrum of classes, including segments on drought-tolerant plants, invasive weeds, growing roses, irrigation systems, organic pest management, veggies for beginners, plant diseases, rain gardens, raising ferns, honeybees, seed saving and urban chickens.

Many classes will address the vital topic of soil-building, which stresses "feed the soil and it will feed the plants." Classes include "Build Your On Topsoil," by Denny Morrelli; "Why Feed Plants Anyway," by Claudia Groth; "Living Soils: Why Bugs are So Important," by Andy Moldenke; "Wondrous World of Worms," by Rhianna Simes; and "Soil Basics," by Marcus Buchanan.

Baldassare Mineo, formerly of Siskiyou Rare Plant Nursery, will talk on "Fantastic Rock Gardens." Chad and Gabrielle Hahn, owners of Mud Puddle Farms, will teach "Perennial Vegetables Culture and Consumption" on the propagation, care and cooking of artichokes, sunchokes, rhubarb, cardoons, asparagus, seakale, sorrel and "walking" onions.

Preregistration by Nov. 3 is recommended to ensure your choice of lunch and classes.

John Darling is a freelance writer living in Ashland. E-mail him at jdarling@jeffnet.org.