There still may be a month or more before spring is full upon the land, but if the winter has been gentle and the temperatures moderate, by early March a watcher can find clear signs of the impending change of season.

For those of us with our eyes focused on the small, spring arrives when buds start to swell.

This is one of those intimate reveals of spring, like finding the first crocus pushing up through an April snow or an early robin sitting on a branch outside your window.

Along the roads and in hedgerows protected from the wind, south-facing plants first show the effect of the warming sun. Last week, I was surprised to see a forsythia bush, snug against a sunny rock wall, already throwing a few golden blooms, but that is surely an anomaly and not the norm.

Grapevines wake slowly from dormancy, but now is when the work begins preparing for future harvests.

As soon as the fields are dry enough to be worked, and sometimes a bit before if there are many acres to cover and the work crew is small, people can be seen moving among the vines.

Among the advances of technology seen in today's farming — power sprayers, automatic grape pickers, even cumbersome machines that spread and pick up the netting used to protect the ripe grapes from marauding birds — field pruning still is done the old-fashioned way: One person wielding a pair of well-sharpened pruners.

I recently saw a demo video of an automated pruner and pre-pruner towed by a tractor, but that technology has yet to be adapted to Colorado's uneven and unforgiving terrain.

Pruning may start as soon as the vine goes dormant, and when you prune may affect bud break, which around western Colorado usually occurs about the time daily average temperatures reach 50 degrees.

This is when the vines "come alive" and start pushing nutrients through the system. Buds turn green and swell and soon push out small leaves. The summer growth cycle goes from there.

Growers tell me the vines pruned later in the season usually start spring growth slightly later than those pruned mid-dormancy. Depending on the grape variety and the chance of a late frost (something common in western Colorado), delaying pruning and bud break may be an option.

Pruning last year's growth isn't difficult, but learning to do it well takes practice as well as a diligent teacher and student.

You prune for several reasons, most importantly because vines produce fruit only on first-year wood. Other key reasons include regulating crop load and matching the training system you want.

This last refers to the system you use to manage the plant's growth to promote efficient, sustainable and economical fruit production.

Grapes are produced from buds that will grow into shoots on 1-year-old canes, those long stems or shoots you see wildly tangled on winter vines.

Pruning allows the grower to shape the vines to get the most production.

Growers, according to their own system and personal preferences, generally use either cane pruning, in which a single long shoot is left and tied to run along a support wire, or spur pruning, in whch the cane is cut short, leaving three to five nubby spurs from which the fruit will grow.

One advantage of cane pruning is that should the weather turn cold, the farthest end of the cane suffers the damage and the parts closer to the trunk may survive.

Spur pruning, on the other hand, is less labor-intensive.

However — there are many qualifiers when dealing with living plants — some recent research has shown that in northern climates (that's us) vine training systems are more important for productivity and reducing cold damage than pruning techniques.

Vines are often trained to a trellis — most often wires are strung between posts — and there are probably as many training systems as there are grape growers and winemakers.

Keeping the vines off the ground allows the cold air to pass under the fruit, reducing cold damage.

State viticulturist Horst Caspari has done a lot with monitoring temperatures at various heights above the ground and has talked about how a few feet and a few degrees can affect a grape crop.

Among the systems you'll see around the Grand Valley are the single- and double-Guyot, Smart-Dyson and, more recently, the Geneva Double Curtain.

All of these allow the grower to control how much air and sunlight reach the leaves and fruit, and offer varying amounts of protection from the late-summer sun.

Once the pruning is finished, the growers and winemakers turn to the thousand-and-one other chores to be done before there is wine to be bottled.

Really, it's not quite that simple, but you get the idea. The vines may be resting in winter, but the growers aren't.

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