Anchorage Daily News

Here is a question every gardener would normally be asking this time of year but for record snowfalls, as was the case last weekend: Do I really need to fertilize my gardens and lawn?

Given that one of the first things that greet gardeners when they visit nurseries and garden centers, snow or no snow, from May on is pallets stacked with all sorts of fertilizers, this might seem to be a strange question. Of course you need to fertilize, right?

Well, actually, you might not. The chemical fertilizer approach for the home market is no different from selling any other product. Labels are designed to induce you to shell out for products: bigger vegetables, higher yields, deeper roots, greener lawns. You know the routine. You have fallen for it for years.

First of all, all fertilizer labels have a trilogy of numbers representing the proportions of nitrogen (N), phosphorous (P) and potassium (K), or NPK. Some emphasize high amounts of nitrogen for leaf growth or "greenness." High phosphorous is touted for great root growth and so on. Others suggest they are "balanced," a nice phrasing that soothes the bewildered who can't make up their mind as to what is really needed.

In theory, you are supposed to get your soils tested and then buy the right NPK mix to make up for deficiencies. The truth of the matter is that natural soils already contain all the nutrients your plants will need, either in humus, which can be NPK-tested, or in biology, which isn't NPK-tested.

The real need for fertilizers arises only when the gardener has previously chemically messed up the soil and reduced its biology. Oddly enough, the main cause of this is use of chemical fertilizers! My regular readers know that destroying the soil food web with chemical salts (i.e. fertilizers) prevents the natural nutrients in soils from being utilized.

Problems are compounded by taking away the organic matter -- grass clippings, leaves and dead plants (as in harvesting vegetables, cutting flowers, cleaning up beds in the fall and collecting leaves and grass clippings) -- that would have provided nourishment for the soil biology that naturally feeds plants.

So what to do? Natural (organic) gardeners don't need fertilizers at all. What might be needed, however, is putting back sufficient organic matter to feed the biology. Compost is best -- no more than half an inch on garden beds and lawns. In lieu of compost, organic "microbe foods" such as soybean, fish, blood meals, corn gluten and the like (which state and federal laws require to be labeled as "fertilizers") will provide the necessary biological nutrient base.

If you have been using the chemical approach, adding the missing microbiology back into your soils is necessary -- not adding the missing NPK the microbiology produces. You can do this with aerated compost tea or compost. Later in the season, you might want to add some form of microbe food to feed your newly established micro-herd.

Is there anything wrong with using chemical fertilizers? Well, yes. The high-nitrogen stuff pushed on you for lawns will require much more frequent mowing and watering. And by killing off the mycorrhizal fungi that feed your trees, shrubs and perennials, you will have to chemical-load them as well.

Moreover, there are health risks. Nitrates go into the water table and can affect drinking water. Babies, in particular, are at risk. Then there is the fact that excessive nitrates cause chickweed and other annual weeds to thrive. Expensive phosphate is locked up and, without biology to release it, is next to impossible for your plants to use.

I know this is going to be controversial, and some purveyors are going to argue otherwise. But it is time to get off the chemical-commercial merry-go-round. I also know that the idea of applying compost to a lawn might prove difficult without a good spreader or a modicum of back work, but it (or aerated compost tea) is the thing to use, not salt-based fertilizers.

Such is the ever-changing world of garden and yard care. Now is a good time to make the conversion.

Jeff Lowenfels is a member of the Garden Writers Hall of Fame. Reach him at gardenerjeff.googlepages.com or by joining the "Garden Party" radio show, 10 a.m.-noon Saturday on KBYR 700 AM.

Garden calendar

• ALASKA MASTER GARDENERS CONFERENCE, May 9-10, features international gardening experts and authors Ciscoe Morris, Larry Hodgson and Sara Williams in addition to local experts on a variety of topics. You must register. Go to www.alaska mastergardeners.org.

• VEGETABLES TO START FROM SEED INDOORS: summer squash, pumpkins.

• VEGETABLES TO (POSSIBLY) PLANT OUTDOORS: peas, chard, spinach, mustard, onion sets, potatoes -- if your soils are thawed.

• RHUBARB: Put a box or paper bag over yours to encourage faster growth and an earlier harvest. Devise some way to anchor your device so it won't blow away.

• WANT A HEDGE? If so, reserve plants at your nursery and pick them up "bare-rooted," which should save you up to 50 percent. Now is the time to reserve.

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