Question
QUESTION: You mentioned on one of your answers about vegetable gardening to let the soil
dry out between waterings and then water deeply.  Since I'm new to this, what or
how much is watering deeply.  If I set up a sprinker, how long should I let it run?  
Any basic help would be great - I ruined my tomatoes last year because I kept
watering them everyday - overly excited that they were growing I guess.  
Thanks!

ANSWER: Tim, most vegetables require 1.5" to 2" of water per week. This is usually accomplished by watering for 12-15 minutes, twice per week. However, many other factors play in, including the type of soil (clay or sand), temperatures, and mulch.

Clay soil tends to retain water longer, but can also result in root-rot due to poor drainage. Sandy soils drain well, but do not retain water long enough to benefit the plants. The best soil is one composed of organic amendments including peat moss, aged manure, and compost. This soil will retain moisture, but still drain well. It also provides constant feeding due to the higher concentration of nutrients, thus reducing the need to fertilize.

Mulch is extrememly important because it cools the soil and helps retain moisture longer. Mulched soils require less watering. It also keeps weeds from germinating.

Finally, be sure to water in the early morning hours. The water tends to seep deeper and benefit the plants more effectively. Watering in the afternoon is often futile because of evaporation. And watering at night, though effective, can lead to fungus disease.

In summary, water for 12-15 minutes, twice per week. During hot periods, you may have to increase the frequency. The soil must be moist 3" below soil level for best results. You can either purchase a moisture meter at your local garden center or place a rain gauge in the general vicinity to measure the amount of water. But one thing to always remember, do not water everyday except during periods of drought. This causes the roots to reach for the surface, which in the long run, dries out the roots and causes the plant to suffer.

I hope this answered your question. Please write again if I can ever be of assistance.

Regards,

Mike

---------- FOLLOW-UP ----------

QUESTION: Thanks so much - Very helpful.  Yes - I was watering at night (knowing not to
water during the day) but not aware the problems it could cause.  I live in
Oregon and the soil here is very much clay.  I dug it up (it's a 9 x 14 spot) and
mixed in 15 big bags of Miracle Grow Garden Soil to the clay.  That seemed
like the right thing to do, but I'm just making it up as I go.  So that was the
base that I planted in. It definately had manure in it, but I'm not sure what
else.

I originally came across your answer on the brown spots on the bell peppers
and realized I was doing something wrong and actually stressing the plants.  
Since I was watering everyday, do you think I've washed away alot of the
nutrients in the soil I added?  I guess more importantly, what should I do now
to minimize any more damage and make the best of this growing season?  As
specific as you can be about any products I should use or depths of new soil
or material would be helpful.  Thanks so much - you've already been a huge
help!!

Answer
Tim, at this point in the growing season, all you can do is mulch with an organic material such as shredded bark or shredded leaves. This will slowly decompose and enrich the soil. It will also retain moisture and reduce the need for watering. Tilling in materials at this stage will only disturb the roots.

This fall, add more amendments to the soil. I would also consider a raised bed since that will eliminate the clay altogether. My vegetable beds are 12" in depth and framed in with 12"X2" cedar. The 12" depth allows me to grow root crops such as carrots and beets, and also provides substantial depth for root development for my other vegetables. I have two compost piles from which I supply new materials to the beds every fall. Throughout the summer, I add vegetable wastes, shredded leaves, grass clippings, and table scraps such as egg shells and banana peels. By mid-October, the materials have broken down and are tilled into the garden. By early spring, the soil is loamy and rich in nutrients. Plants absolutely thrive in this medium.

I wish you luck the rest of the growing season. Believe me, each year will get better as you gain experience, and as the soil continually is enriched by following the procedures I've outlined above.

Have a great weekend.

Mike