By Tamara Galbraith

It's the middle of summer. The heat is on, and while you're sporting a nice tan, your plants have suddenly taken on a pale, pasty look. What gives? Say hello to the fungus disease known as powdery mildew.

A common condition found on plant life throughout North America, powdery mildew is characterized by spots or patches of white to grayish, talcum-powder-like growth. Fortunately, it is usually more of an effect than a problem itself. In other words, in addition to treating the plant, you'll probably want to take a look at the surrounding conditions and make some adjustments.

First and foremost is to make sure you give plants plenty of room. Good air circulation goes a long way. Trim plants that have gotten crowded or bushy. Avoid overhead watering, and don't make late summer applications of nitrogen fertilizer, as powdery mildew loves to attack the newest plant growth which, of course, nitrogen encourages.

To halt the fungus in its tracks, spray with a good fungicide, such as Bonide Fung-onil. And next time around, try to choose the more mildew-resistant cultivars of plants that are most susceptible to powdery mildew, like zinnias, beebalm, crape myrtles, cucumbers and squash.

By Tamara Galbraith

Ok, hold up a trowel if you know what USDA Hardiness Zone you're in.

As a gardener, knowing your zone is one of the most basic and important pieces of information you can possess. Your hardiness zone tells you what kinds of plants grow well in your area, and when to plant, according to your climate.

Originally developed in 1960, the USDA Hardiness Zone Map divides North America into 11 separate zones. There are also two 'subzones,' labeled "a" and "b" within zones 2 through 10. The map is divided based on the average annual minimum temperature range, by increments of 5 degrees.

For example, the average yearly minimum temp for zone 8a is 10-15° F. The average yearly minimum temp for zone 8b is 15-20° F.

So, when you read a description for a plant that says it grows in Zones 3-8, and you know you're in Zone 7, it is likely the plant will do well in your neck of the woods.

The rules can be bent in either direction. You can create heated "micro-climates" in your landscape (a south-facing sunny site against a brick wall, for example) and artificially raise your zone a whole step. Conversely, warm climate gardeners can put a plant that prefers cooler temps in complete shade, in some cases.

Of course, other cultural and environmental issues contribute to your plants' well-being, so while the USDA Hardiness Zone map is a great tool, it is not foolproof and should be looked at as only a guide. Several U.S. states also have their own hardiness maps, which are much more detailed. The American Horticultural Society also recently came out with a Heat Zone Map, sort of the opposite of the USDA Hardiness Zone map. The Heat Zone Map bases the zones on the average number of days each year that a given region experiences temperatures over 86° F.

Confused by all these zones and maps? Yeah, me too sometimes. But being a good gardener means also being an educated gardener. In addition to your local nursery experts, several sources out on the Web will tell you all you need to know about your area and the plants that do well there.

Web Sources:
USDA Zone Map
Heat Zone Map

By Tamara Galbraith

Mulch. The word doesn't exactly roll off the tongue like a Shakespeare sonnet, does it? But for everything the word lacks, the actual stuff, when placed on your garden beds around flowers, vegetables, trees and shrubs, compensates by helping your plants live longer in summer's heat by keeping roots cool and soil at an even level of moisture.

Wood mulches look better but, in general, provide less nutrition to your plants. We prefer using a nutritious mulch, such as Master Nursery Black Forest Organic Compost, unless you are mulching a large unplanted area and need the look of a good wood mulch.

So, how much mulch to use? Generally, you should plan to cover all exposed soil areas with 2-3" of mulch. DO NOT place mulch right up against the stems of plants and trunks of trees. Back off about 2" or so, as this allows water and air to reach the base of the plant, and also ensures against rotting from constant contact with the mulch. Also, don't think that more is better in the case of mulch. With trees, especially, think "wider" not "higher." Avoid piling mulch up in a volcano formation around the trunks of trees and thinking it will help - it won't.

There are several online calculators that help you figure out how much mulch you'll need to buy, depending on your garden size. Generally, one cubic yard of mulch covers about 100 square feet at 3" deep.

Be sure to fluff and add to your mulch every once in awhile, as it will compact and break down over time.

By Tamara Galbraith

Summer's in full swing, and your previously glorious flowers are starting to look a little ragged around the edges.

Many plants will benefit - and even rebloom - after a mid-summer session of "deadheading," that is, removing spent flowers and/or stems to promote new growth.

Here's a quick guide of deadheading techniques for different types of flowers:

Pinch off individual dead flowers on: balloonflower, bellflower, daylily, delphinium, foxglove, hibiscus, hollyhock. (Also included: some irises that will rebloom in the fall, depending on the variety.)

Do an overall snip of dead blooms (about 2" below the flower) on: blanketflower, columbines, globe thistle, goldenrod, geranium, Jacob's ladder, salvia, coreopsis/tickseed.

Cut the entire spent flower stem off to either a sideshoot or to the plant's base on: baby's breath, bleeding heart, cardinal flower, catmint, coral bells, foamflower, gaura, Jupiter's beard, lavender, lupine, mullein, painted daisy, pincushion flower, coneflower, Shasta daisy, speedwell, spiderwort, Stoke's aster.