West of the Cascades, the question of which method is superior is a bit complex, with pros and cons on both sides.  Without a long winter freeze to set populations back, permanent thick mulch quickly breeds so many slugs, earwhigs, and sowbugs that it cannot be maintained for more than one year before vegetable gardening becomes very difficult.  Laying down a fairly thin mulch in June after the soil has warmed up well, raking up what remains of the mulch early the next spring, and composting it prevents destructive insect population levels from developing while simultaneously reducing surface compaction by winter rains and beneficially enhancing the survival and multiplication of earthworms.  But a thin mulch also enhances the summer germination of weed seeds without being thick enough to suppress their emergence.  And any mulch, even a thin one, makes hoeing virtually impossible, while hand weeding through mulch is tedious.

Mulch has some unqualified pluses in hotter climates.  Most of the organic matter in soil and consequently most of the available nitrogen is found in the surface few inches.  Levels of other mineral nutrients are usually two or three times as high in the topsoil as well.  However, if the surface few inches of soil becomes completely desiccated, no root activity will occur there and the plants are forced to feed deeper, in soil far less fertile.  Keeping the topsoil damp does greatly improve the growth of some shallow-feeding species such as lettuce and radishes.  But with our climate’s cool nights, most vegetables need the soil as warm as possible, and the cooling effect of mulch can be as much a hindrance as a help.  I’ve tried mulching quite a few species while dry gardening and found little or no improvement in plant growth with most of them.  Probably, the enhancement of nutrition compensates for the harm from lowering soil temperature.  Fertigation is better all around.

Windbreaks

Plants transpire more moisture when the sun shines, when temperatures are high, and when the wind blows; it is just like drying laundry.  Windbreaks also help the garden grow in winter by increasing temperature.  Many other garden books discuss windbreaks, and I conclude that I have a better use for the small amount of words my publisher allows me than to repeat this data; Binda Colebrook’s [i]Winter Gardening in the Maritime Northwest[i] (Sasquatch Books, 1989) is especially good on this topic.

Fertilizing, Fertigating and Foliar Spraying

In our heavily leached region almost no soil is naturally rich, while fertilizers, manures, and potent composts mainly improve the topsoil.  But the water-wise gardener must get nutrition down deep, where the soil stays damp through the summer.

If plants with enough remaining elbow room stop growing in summer and begin to appear gnarly, it is just as likely due to lack of nutrition as lack of water.  Several things can be done to limit or prevent midsummer stunting.  First, before sowing or transplanting large species like tomato, squash or big brassicas, dig out a small pit about 12 inches deep and below that blend in a handful or two of organic fertilizer.  Then fill the hole back in.  This double-digging process places concentrated fertility mixed 18 to 24 inches below the seeds or seedlings.