Over the past 50 years that vegetable nutrients have been measured, the decline in nutrients has been startling. Some experts blame farmers for the decline in nutrients, as they grow crops faster and faster, but changes in favored varieties of vegetables may be to blame as well.

We can't blame farmers for trying to make their land as productive as possible, but we should seek the cause for this decline.

We now have to eat more calories to get the same nutrients we got from our food 50 or 60 years ago. That might partially account for the epidemic of obesity we've been suffering in this country: We're overfed but hungry for nutrition.

We gardeners have some responsibility in this area, too. We don't need to grow the biggest, fastest-maturing vegetables on the planet. Take it easy with dilute natural fertilizers, and pay attention to taking good care of your soil. That will produce good vegetables.

Also, pay attention to your seed. Are you growing varieties that taste good to you? Good enough that you won't waste food? Can you save your own seeds and grow that crop again next year?

A TRELLIS WILL HELP YOU MAXIMIZE A SMALL SPACE

One of the ways we can maximize your food production from a small lot or even a balcony is to grow "up." That means we must erect a trellis of some kind. What do you intend to erect it on? You could set poles (bamboo, conduit pipes, PVC or even rebar) in containers, and tie up string trellises.

String trellises are available in garden centers, but if you intend to use them year after year, that gets costly. Removing dead plant material from string netting is tedious and time consuming, so we usually discard the trellis and buy a new one the next year.

Once you decide you want to grow upward in subsequent years, you could use a section of galvanized fencing wired to your poles. One way to make growing upward more flexible is to pound "sleeves" into the ground so you can insert or withdraw your poles. The sleeve material must just have a hole larger than the stakes you intend to use. I've been using scrap galvanized pipe of a size larger than my pipe poles.

I am using two such trellises in my raised beds, and intend to add a third this spring, all with broad sides facing north and south. Our prevailing winds are east-west, and when foliage completely covers a trellis oriented in either of those directions it may act as a sail in the wind and bend or blow completely over.

An alternative to the rectangular trellis is a teepee of bamboo or tree prunings, with cord wrapped around, or a commercial expandable cone-shaped structure. I grew vining Achocha on one of those cones a couple of years ago, and it was amazingly stable.

If you're intending to grow any vegetable heavy enough to require hammock support, it's most easily affixed to the fence treatment, though.

FOR MAXIMUM GREENHOUSE INSULATION, BUILD A 'WALIPINI'

Two weeks ago I wrote about different greenhouses, before I learned about "walipini," or "warm places" because they're mostly underground. Enter "walipini" in your search engine for descriptions and photos of this clever installation. They should have called it "hot diggety," I think, because that would be more accurately descriptive.

It takes advantage of the insulating factor of earth, but I'd build a more steeply sloped roof than they show. We don't get deep snows often, but even a 6-inch-deep snow is heavy enough to pull my cover off the bed's ribs.

Send garden questions to melauter@ earthlink.net or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.