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My wife and I just returned from two wonderful weeks visiting, studying and hiking in the national parks of the Sierra Nevada mountains of California. We are talking about the big trees, high waterfalls, beautiful vistas and some record unexpected early season snow.

Of course I was very interested in the plant communities along the way. What struck me most was the importance of microclimate. The Yosemite Valley is just a mile and a half wide and yet the opposite sides of the valley support an entirely different group of plants.

With the high mountains, the side of mountain that catches most of the sun is much hotter and thus drier and vegetation is more sparse and challenged. The other factor is elevation. In those mountains a day trip is the same as traveling from the Florida border to north of the Hudson Bay if you are studying the plants.

While no where as pronounced here, microclimates are important in our local gardens. Soil, moisture, exposure, hills, wind and our proximity to the Chesapeake Bay, Atlantic Ocean and the Susquehanna River all come into play. Factors like these blur the lines between science and experience or art.

When I had the orchard I knew that a fruit blossom was most subject to freezing for a very short period just before they opened. If you can plant on a hillside, the air movement will drag the cold temperatures down the hill.

Another prudent move was to plant the same varieties of a given fruit on the north and south side of a hill. This usually staggered the bloom time and extended harvest season several days.

One of my favorite tales came from a man from Delaware. He was enthralled by the taste of our strawberries and wanted to grow the same ones in his garden a short hour away.

I told him the variety I planted and he ordered them. He wasn't happy. He repeated the process and again was not happy. He came to my fields and dug runners and again failed. Blame the microclimate.

On the ornamental side, I planted two identical coleus in identical patio pots and put one on the north side of my house and the other on the southeast side. You guessed it. You would have had a difficult time saying that it was the same plant.

Another example was the reseeding perennial blue flax. It danced through my garden and yet was a total failure on the other side of the hill several miles away.

This story has a moral. Many ornamental plants are easy to grow and will thrive regardless of what we do to them. Many others have rather exacting requirements. When you find a new plant try it, but don't make it the centerpiece of your landscape until you are sure you can grow it.

Most of us are familiar with the large tree, the American sycamore. It's the one with the large leaves, flaking white bark, and the small balls for seed heads that favors growing along stream banks or sites with plenty of moisture.

You may also have observed that it has trouble getting leaves in the early spring. Close inspection would have shown disease killing the first round of leaves. Fortunately for this plant, a second flush of leaves forms and by mid summer you see few traces of this spring problem.

The disease is Anthracnose. It thrives in cool, moist conditions. Naturally, we can suspect that 2004 was an exceptionally bad year. The real problem is that Anthracnose or some strain of it attacks many plants in our gardens or landscapes.

Tomatoes and vine crops are targets in the vegetable gardens. The plant breeders have done an excellent job of creating plants with a high level of resistance. Some of the heirlooms can be troubled, but these problems can be mitigated with careful sanitation or chemical fungicide.

A target in our landscapes is the popular common dogwood. With the dogwood, Anthracnose can be a fatal problem. Drive through the southern Appalachian and Smoky Mountains in the spring and you will see the demise of the native dogwood.

Normally the dogwood is an under-story tree, which is usually a slow drying site. The disease flourishes on wet leaves, and will attack new growth, killing branch tips and eventually weakening and destroying the tree. If you see twig death in one of your dogwoods, it should be cut out, cutting about a foot below the visible infection.

The good news is that we are just on the northern edge of the area with the greatest damage. In fact, I have a pair of pink ones in my yard for the last dozen years who never have shown anything beyond leaf damage. There are reasons, and I will get into that in a few sentences.

As with other plants, the breeders have made crosses that offer resistance. Using the Latin, the native Cornus florida is the biggest problem. If you find cultivars with fancier names, your plant will have some level of resistance. The large flowered, late blooming Kousa dogwood is resistant.

Plant talkers frequently use the word resistant in their descriptions. Don't be mislead. Resistance means added defenses but never total disease victory. Remember that.

Back to the dogwood, the key to success is cultural practices. As I said, the dogwood is an understory tree, but the fact is that it can grow in full sun where its leaves will dry more quickly. Avoid wetting the leaves with irrigation. Provide good air circulation.

I practice the above with my pink Cornus florida and have yet to face the need to remove dying branches.

Diseases, even with the same name, have varied looks and effects on different plants, but diseases can be managed. Practice sanitation. Check for resistance. Avoid excessive irrigation. Do not put problem plants in problem sites. Occasionally you may need some chemical aids.

I hope that you have your pruning shears well oiled and well sharpened. I also hope they are stashed in your garage or basement where they are out of sight and out of mind. Except for cleaning up storm damage your plants would favor a vacation for the shears lasting from mid August until after Christmas, maybe a bit longer.

From a disease and insect point of view, the quicker your pruning cuts heal, the better. Healing occurs quickest on an actively growing plant.

Pruning reduces winter hardiness. That does not matter if we are growing plants native to the Arctic, but since we grow many plants that are more marginal for our climate, winter hardiness is always an issue.

With our winters, we can expect wind every year and occasionally temperatures under zero. Either of these conditions can work against our plants. Why not wait until the worst of winter is over to evaluate winter damage and prune accordingly?

First on the list to prune are short needled evergreens and fruit trees, like apples and pears. When I had 30 acres of apples I would start just after Thanksgiving so I could complete the job. Christmas tree growers are busy in the middle of the winter. If I had just several of any of the above I would finish by the end of February.

If I had grapes or blueberries I would think about late February or early March. I would also think about pruning deciduous (lose their leaves) trees in this time slot. Ideally, they are pruned just before the sap starts to rise to reduce bleeding at the cuts.

Tender fruit trees are pruned best about bloom time. These include peaches, cherries, nectarines, and plums. The ones with just one seed are the tender ones.

Summer flowering shrubs should wait until after you have assessed the winter damage. Then prune to thin, shape and mitigate the winter damage. Since the late summer bloomers bloom on new wood, you can prune these hard if you wish.

Last spring was a bit unusual. After a colder winter, the normal March warming came only to be followed by two days of wind and freezing temperatures. This did a number on many shrubs. It was lethal to many butterfly bushes, especially those that had been pruned.

Those of us that were dismayed by these events and puzzled what to do were greatly rewarded as shrubs and trees recovered remarkably well. It was mid to late May until this event played itself out.

My bottom line with the fall bloomers is to wait and wait. I like mid April, even a bit later.

This is getting a bit long so I will quit after adding briefly that the spring bloomers are best pruned immediately after bloom to give the plant plenty of time to form buds for next year.

It feels like fall. It looks like fall. The good news for us garden optimists is that in five months it will feel like this again and it will be spring. One way to increase your spring enjoyment is to add some spring flowering bulbs to your garden.

The ideal time to plant them is in the fall as night temperatures drop below 50 degrees and before the ground gets hard from freezing. That's now, and I'll let you guess how long that will last.

Traditional wisdom suggests that they receive a planting depth of two to three times the size of the bulb. Ignore the mulch or mulch lightly ahead of winter as the temperature falls. Heavy mulch may increase disease problems, however disease is never much of a problem with spring bulbs.

Bulbs are not picky about soil. You and your bulbs will not be unhappy unless you pick a boggy spot. Stay away from wet feet and it's hard not to have success.

The biggest problem with bulbs is what to do with the foliage between spring bloom and when it naturally disappears in the early summer. Ideally, you do nothing. A translation and suggestions about the last four words follows.

I recently grabbed 50 daffodil bulbs which are destined to find a home in an evolving garden that over the last dozen years has transformed itself repeatedly, after starting as a planting of odds and ends.

First, the Shasta daisies seemed to dominate. Then the black-eyed susans took control, and finally, the coneflowers are top dog. There are lots of other perennials that are holding their own, but it looked a bit underwhelming last year in the earliest days of spring.

In go the bulbs, and their dying foliage will be covered by other plants. In the shade, you can use hostas, ferns, astilbes or a host of other plants to do the same job. Bulbs will do well in deciduous (drop their leaves) shade since these sites are sunny while the bulbs are active and shady only while they are resting.

If you wish to scatter crocus or other small bulbs throughout your yard, you should set the mower higher until their foliage completely dies.

Most bulbs will naturalize. The exception is the large flowered tulips that will go down hill rather quickly. It wouldn't be a bad idea to separate thickening plantings every half dozen or so years. I'll tell you that, but I doubt that that will ever be a priority in my garden.If you live in a squirrel-dominated community, and they steal your tulip bulbs, you can thwart them by laying a small piece of one-inch mesh chicken wire over the bulbs when you plant. It seems they only like tulips.

Fertilize sparingly. Do it after bloom. Use a bulb fertilizer or one that has a near even ratio. The only good reason to fertilize is if you are trying to coax a second or third year out of the large flowered tulips.

Think spring. Act now.

To my dismay I found my windshield a bit thicker than normal several days ago. The low end of my yard glistened rather white. Granted, I live in a cold hole near the west branch of the Octoraro, but as I suggested last week, colder weather is rapidly approaching.

There was no damage to even the tenderest annuals, just a reminder that the clock is ticking toward winter.

Last week we talked about plants above the ground. Today let's go underground. In the vegetable garden it's time to get the potatoes, sweet potatoes and onions out if you haven't already done so. It may be an old wives tale, but I have always been told that a killing frost on sweet potato vines reduces their quality and storage life.

We never do red beets beyond the active growing season, but they can be canned. The taste of turnips improves with frosty weather. I suspect that carrots are almost as tough as turnips.

Potatoes need to be stored in a cool, damp site. If your supply will last past Christmas, or you will be buying big bags of them after Christmas, adding a few apples to the closed bag will retard spring sprouting.

Sweet potatoes should be dug on a warm day, left air dry and then stored in one of your warmest rooms. As a kid we put them near the chimney in an upstairs room. We favor some of the local varieties, but my wife cheats. She cooks them off and puts them in the freezer. That's not quite as good as fresh but sure solves the storage problems.

We never have much luck keeping onions beyond our short-term needs. Turnips can stay in the garden until the ground is ready to freeze and are then treated like potatoes.

The summer flower bulbs or corms, like gladiolas, dahlias, cannas and green elephant ears need to be dug before they get a steady diet of hard frosts. I'm sure there is someone out there that will leave them in the ground and claim great winter survival. I just won't believe them, but if it works, do it.

Again, I suggest digging on a warm day so you can let them air dry. Then shake off as much dirt as you can. A dip in a fungicide solution or a ten- percent solution of chloride will greatly reduce mold.

Store them in the dark, in a spot not too dry but not too wet. A paper or burlap bag is fine. Packing them in peat moss or fine wood chips is even better, but is a lot more work if you have very many.

The black elephant ears that are becoming very popular are just a vegetative root. We dig ours, cut it back severely and put in a pot. It adds some nice winter foliage to a warm sunny corner by a window. I can see the day coming when the size of the pot and the strength of my back will battle as equals.

It's fall. There is a lot to do in the garden. Don't spend all your time scraping your windshield.