day. (Ryegrasses are known to make more roots than most plants.) I
calculate that a cubic foot of silty soil offers about 30,000 square
feet of surface area to plant roots. If 3 miles of microscopic root
tips and hairs (roughly 16,000 lineal feet) draws water only from a
few millimeters of surrounding soil, then that single rye plant
should be able to continue ramifying into a cubic foot of silty soil
and find enough water for quite a few days before wilting. These
arithmetical estimates agree with my observations in the garden, and
with my experiences raising transplants in pots.

Lowered Plant Density: The Key to Water-Wise Gardening

I always think my latest try at writing a near-perfect garden book
is quite a bit better than the last. _Growing Vegetables West of the
Cascades_, recommended somewhat wider spacings on raised beds than I
did in 1980 because I'd repeatedly noticed that once a leaf canopy
forms, plant growth slows markedly. Adding a little more fertilizer
helps after plants "bump," but still the rate of growth never equals
that of younger plants. For years I assumed crowded plants stopped
producing as much because competition developed for light. But now I
see that unseen competition for root room also slows them down. Even
if moisture is regularly recharged by irrigation, and although
nutrients are replaced, once a bit of earth has been occupied by the
roots of one plant it is not so readily available to the roots of
another. So allocating more elbow room allows vegetables to get
larger and yield longer and allows the gardener to reduce the
frequency of irrigations.

Though hot, baking sun and wind can desiccate the few inches of
surface soil, withdrawals of moisture from greater depths are made