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.
Foliar feeding is another water-wise technique that keeps plants
growing through the summer. Soluble nutrients sprayed on plant
leaves are rapidly taken into the vascular system. Unfortunately,
dilute nutrient solutions that won't burn leaves only provoke a
strong growth response for 3 to 5 days. Optimally, foliar nutrition
must be applied weekly or even more frequently. To efficiently spray
a garden larger than a few hundred square feet, I suggest buying an
industrial-grade, 3-gallon backpack sprayer with a side-handle pump.
Approximate cost as of this writing was $80. The store that sells it
(probably a farm supply store) will also support you with a complete
assortment of inexpensive nozzles that can vary the rate of emission
and the spray pattern. High-quality equipment like this outlasts
many, many cheaper and smaller sprayers designed for the consumer
market, and replacement parts are also available. Keep in mind that
consumer merchandise is designed to be consumed; stuff made for
farming is built to last.