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The Monday before Thanksgiving I ventured a bit north of here and was startled by the white roofs and the patchwork of snow and green on the ground. I guess that season is nearing.

On the way home I could still get excited about the colorful leaves clinging desperately to a significant number of trees. The wind, rain and temperatures of the last week have done the job on most of the leaves near my house.

That leaves one important garden chore perhaps undone. Yard grass and a heavy coat of leaves are not friends. Rake them, blow them or visit them with several passes of the riding mower, but whatever you do compost them or incorporate them somewhere in the garden.

Maple leaves, especially the large ones found on the common Norway maple that was a favorite planting 20 or 30 years ago, will kill most grass if left where they land.

Another job that could be waiting is the mulching of any plants you added this fall. Waiting for temperatures that freeze the soil and then mulching will prevent or minimize heaving caused by the ups and downs of temperatures that we have in the winter.

I did a lot of early fall mulching, only to read that mulching too early is a winter lodging invitation to moles and voles. I have spotted a few mole tunnels, but probably not enough to be concerned.

Moles are those stubby fat ones with the pointed noise and tails who are seldom seen above ground. They eat grubs (insect larvae) and will not generally damage plants except in very high concentrations. Their tunnels just contribute 'ugly' to the landscape.

Voles, on the other hand, are small, skinny, hopping mice that will do a number on tender bark and roots. The problem is that they love to share the mole tunnels.

As a kid I remember dad had a serious collection of slabs of tin and plywood he used in the orchard. A slab, some poison and a big stone or cement block was his answer to voles that can devastate fruit trees. My working cats are also quite effective.

Returning to the thought of snow and, of course, clearing it comes to mind. The first defense is a shovel, snow blower or some plowing device. What I want to comment on is what then.

Most of us use some salt or snow melt to keep our walks clear of ice. They work chemically by lowering the freezing point of water melting. Their chemical action continues in the nearby soil or runoff areas.

Usually this is not an issue, but if you use a lot of these materials, have plant problems along your walk or drive, or have some landscaping beside a public road it might be wise to consider some salt tolerant plants.

Other options include sand, gravel or mulch. They melt snow when the sun warms their dark surfaces. They work about as well as the chemicals. For me, sand refills the cobblestone walk while mulch can easily be sweep into the adjoining flowerbed.

If I wasn't a fan of our changing seasons I wouldn't like winter. On second thought, tolerate might be a better word.

Last week I told you about who plant breeders are. This week, we'll talk about what they do.

Breeders travel around the world for undiscovered specimens to cross with existing plants. The Wave petunias were bred by a Japanese beer maker searching for new hops in South America. He brought one of the wild petunias back to Japan and crossed it with garden petunias and Voila! A petunia that revolutionized your flower bed.

Sometimes, they stay at home. Jim Ault at the Chicago Botanic Garden and Richard Saul at Itsaul Gardens in Georgia crossed 2-3 native North American coneflowers to get the new yellow, orange, and reddish-pink echinaceas that are so popular for late summer perennial borders. The Meadowbrite series came out of Chicago and the Big Sky series came from Saul's efforts in Georgia.

The mechanisms of plant breeding are simply taking pollen (male) from one parent and putting it on a receptive flower stigma (female) of another parent. This is called a cross. Think of breeders as really tall bees.

The difficulty lies in keeping ONLY the parent pollen on the stigma. To this end, breeders put bags around each flower to prevent foreign pollen. If you are lucky, the flower you are breeding is self-incompatible (unable to be pollinated by itself) or male sterile (makes no pollen). If not, breeders must emasculate each flower (remove self pollen). This is generally hand-done, a very labor-intensive work.

After the flowers are fertilized, the seeds begin to grow. If the cross is between 2 different species, the seeds may not grow to maturity on the plant and must be grown in tissue culture. This is a method of growing plants in a lab under sterile conditions with artificial hormones and nutrients given to them in a gel-like substance.

When the seeds are collected the results of the cross are planted and evaluated for beneficial characteristics. Often further crossing is done, either back to one of the parents, or among siblings, or to something else entirely. Once a breeder is happy with the result, the plants are trialed.

Trialing takes 2-5 years, at various locations around the country, comparing the new plant to what is already available in the marketplace. Who needs another red geranium if it isn't better than the ones already for sale?

I will add one caveat- when several breeders are working on one new thing sometimes the first to the market isn't the best and everyone gets burned. Be sure to ask at your garden center if they have had good experience with a new variety before you try it.

Next spring when you are looking closely at your favorite flowers, find the pollen and the stigma and rub them together. Who knows, it might become a passion for you, too.

Now that the gardening season is winding down, I thought we'd spend a little time on a subject near and dear to my heart. Plant breeding.

Why are there so many new Echinacea and coral bell hybrids and where did they all come from? Not to mention iris, daylilies, and new annuals every year.

Some specialty perennials have been bred for hundreds of years. In 16th century Netherlands, a few tulip bulbs and seeds were brought from Turkey to the University of Leiden. Carolus Clusius, garden curator, began breeding them, sparking "Tulipmania".

In a few short years, a pound of prized cultivars sold for thousands of dollars. Fortunes were made and lost. Almost every aristocratic family had tulips as a symbol of power and prestige.

A futures market was even started for the trading of tulips. In the 1630's the bottom fell out of the market, but the bulbs remained popular and to this day the brightly-colored spring favorites are part of the Dutch identity.

Can you imagine a garden with out impatiens? Believe it or not Claude Hope introduced the first impatiens, the Elfin series, in 1969. Impatiens were an orange weed 3-4 feet tall, native to West Africa, before Claude started working on them at his home in Costa Rica.

Sometimes new hybrids need to wait for their time to come. Three decades ago a Ball Seed salesman, who collected unusual begonias, bred Dragon Wings. The powers that be didn't know what to do with such a large, enthusiastic begonia when the fashion was for small balls of color. Perseverance paid off and today Dragon Wings begonias are one of the best sellers for PanAmerican Seed.

Daylilies and irises are primarily bred by back-yard garden enthusiasts. Search the internet and you will find hundreds of cultivars of either. Flowers with only one stigma (female part) and prominent anthers (male part) are easy targets for amateur plant breeders with limited time and space.

David Culp, a local gardening consultant, breeds hellebores and has helped to popularize this wonderful genus. His Brandywine Hybrids introduced many new colors to the Lenten Rose.

Public gardens such as the Chicago Botanic Garden and Longwood Gardens often have breeding or selection programs and have introduced plants of merit. 'Longwood Blue' Caryopteris and the Meadowbrite series of Echinaceas from Chicago readily come to mind.

Universities also have long been sources of new plants. Dick Craig at Penn State has given us the Martha Washington geraniums usually on the market today. He was also instrumental in popularizing seed geraniums. 'Husker Red' Penstemon, the Perennial Plant of the Year 1996, was bred at the University of Nebraska. Most of the land grant universities have breeding programs of some nature.

Of course, private companies introduce dozens of new perennials and annuals each year.

Next spring and summer go outside and really look at your flowers. If you like what you see, thank a plant breeder.

When was the last time that we saw so many leaves still hanging around in early November? When did so many leaves land on the ground with so little color? Blame the weather of course. I'll try to explain without more information than we need.

In our climate all plants either die or head into dormancy as frost and cooler temperatures arrive. Day length and available moisture also play significant roles. Day length is consistent from one year to the next but the other two can vary greatly.

All plant activity results from chemical activity in the plant. Perhaps a good analogy would be hormones in people.

Lack of moisture, or water stress, increases the concentration of abscisic acid, which in turn encourages the plant to shed its leaves. This offers the plant an effective way to conserve water when the growing season is ending. That explains the early leaf drop before much color appeared.

The wonderful fall colors are in the leaves from new spring growth to fall leaf drop. They are hidden by the active food-producing chlorophyll in the leaves. It is when growth slows and the chlorophyll fades that the colors appear. The significantly higher temperatures of September and most of October worked to maintain growth and delay colors.

I don't think I'm dreaming when I say that with the recent heavy rain and several frosty mornings that we are seeing better color. Unfortunately, too many leaves have already dropped to make this a banner year.

As the plant gets ready for winter, food is transferred to the roots. Woody plants also store extra water in their stems. The latter storage can be impacted by stem wounds. Thus, pruning in the fall should be discouraged. Likewise, early top removal of perennials can reduce the transfer of food to the roots.

One sidebar is that often contact herbicides are quite effective when applied in late fall. A month or so ago I mowed a small field that is polluted with thistles. Right now the thistles look lush and green.

Given what we have talked about above, the weed killer would now be quickly transported directly to the roots, unlike spring or summer applications. I sure hope I can find time to have a good-bye party for those thistles. I know of no other way short of herbicides to get rid of Canadian thistles and now is a good time to attack.

I think you can also surmise from the above that anything that encourages growth late in the season has the potential to slow dormancy and increase the risk of winter injury. The fertilizer on perennials and shrubs should cease no later than early August if you use it. The water hose should be put away given the recent heavy rain.

As you can guess, something approaching the opposite happens as spring arrives. One thought is that well-mulched soil will have a more uniform and cooler temperature than one that has no mulch. The cooler temperature will delay spring growth a bit and maybe save the plant from damage during late spring frosts.

All plant growth is cyclical and dependent on environmental conditions. Dormancy is a natural "rest" period for perennials, trees and shrubs. That time is about here.

If the six-week absence of rainfall in September and early October foiled your plans to add plants to your garden, don't despair; get moving. Although more seasonal temperatures are in the forecast there is still a bit of time if you follow a few guidelines.

Evergreen trees and shrubs, unless planted in a rather protected spot, may need some extra protection. This protection can be a physical barrier like burlap or a spray to reduce water loss.

The issue with evergreen plants is that they continue respiration even during the winter. Although respiration slows greatly in cold weather the plant continues to use water. Problems can occur if the roots are not established enough to supply the needed water.

It most likely goes without saying that the larger the plant the larger the potential for problems.

Plants that lose their leaves are generally less problematic. At this time of year, as the leaves disappear, respiration almost ceases. In reality, the next several weeks might be the best time if adding a sizable tree to the landscape is planned.

Planting now would give you a bit of time for the roots to establish before the high demands of growth come in the spring. The soil temperature now is probably about the same as it is in late April and early May when most of us get into a planting frenzy.

Soil temperatures make the roots. Air temperatures make the plant. It goes without saying that good roots make good plants and poor roots make poor plants.

At this time of the year I would most likely pay a bit more attention to the overall hardiness of the plant. Things that are marginal or difficult should wait until next year.

Spring flowering bulbs can still be planted without much thought. Some weeks ago my daughter, Kris, covered that topic better than I ever could. Bulb Article

If thinking about perennials, reread the comments two paragraphs back and grab the shovel. Warm season ornamental grasses and lavender are two that quickly come to mind that are iffy on my late fall planting list.

My guess is that the vegetable garden has about run its course for the season. Planting a cover crop of something like rye now to be tilled in the spring will pay dividends over time.

I also threw out about 100 pounds of grass seed as part of a major project that commenced with the first rains about ten days ago. I'm starting to see some hints and may be brazen enough to scatter a bit more in the next several days.

The only problem with planting now that I can think of, is that with a quick change in the weather the roots of container grown plants may not completely grab the soil. The up and downs of day and night temperatures may push the plant upward.

There have been occasions when I have seen plants heaved halfway out of the ground. I offer two solutions for this problem if it occurs. First find the family member with the biggest foot and have them press the plant back into the ground.

Second, if you let the ground freeze before you mulch your new plantings that will stabilize the soil temperatures and greatly reduce the potential for heaving.

The clock is ticking, time is running out, but your shovel could successfully do a few more errands if you wish.