Watering Dahlias
Presenter:  Wayne Lobaugh
06-11-13
Wayne Lobaugh gave a very interesting talk with Power Point slides showing how he irrigates his dahlias.
He has a very low capacity well(13 gallons per minute) and must balance watering his dahlias with their
domestic water use. He uses an automated system with an electronic controller that turns on numerous
zones for one to two hours depending on the season. He says that at the warmest point in the season
each dahlia plant needs two gallons of water per day. He uses t-tape that he buys from Drip Works. His
dahlias are planted in double rows with about a foot between the rows. Since he has such feeble well, he
runs four drip lines on each double row(he is in the process of determining if three would be enough).
Each 100 foot long row with the four T-tape lines is a zone. He has to run the system 24 hours per day(
two hours per zone, apparently 12 zones) during the very hot weather. The electronic controller is very
flexible as to what zones run for what period of time. The T-tape has the holes every 4 inches and the
water pressure is 8 pounds and is set by a pressure reducer placed very close to the beginning of each
zone. Half inch poly tubing forms the "manifold" for the four lines. He has a 200 mesh filter to keep out grit
from clogging the lines.

He says that many other growers have switched to T-tape. Dan's Dahlias uses it too. One of our club
members has a t-tape system also.

There are many ways to irrigate dahlias and Swan Island uses the huge commercial sprinklers with the
huge aluminum pipes that are moved around the fields. They have a nearly unlimited water supply from a
river(very old water rights) and I know at least one field has a well. Phil Mingus uses sprinklers too.

It may be surprising that we have to water our dahlias so much here in the rainy Pacific Northwest. But our
weather in the summers is exceedingly dry, especially the period from July 1st through September 15th.
There have been July's with no rainfall at all. We sometimes get some thunder storms in late August but
not in the last several years.