This year has been the "endless summer", day after day of hot sunny weather without rain, not even getting much in the way of thunderstorms. Once the soil reaches a certain level of dryness, where even trees and shrubs show the effects of drought, it becomes an uphill battle trying to resuscitate them by watering; a hose can barely begin to keep pace (and not to mention the water bans, restricted to watering every other day, which isn't too bad). The soil can become so hard, dry and dusty, that it reaches an "unwettable" state by actually repelling water.
Some plants cope just fine with the drought, others of course, do not. Has anyone used any techniques to help the more moisture sensitive plants stay hydrated? I was thinking about doing the following, I wonder if it would work or whether it would be a waste of time:
Take 2-liter soda bottles and cut off the bottom ends. Drill a few small holes in the caps, them screw them back on. Submerge a few open-ended bottles into the ground around water-sensitive plants (such as Kirengoshoma). Fill the bottle with coarse gravel, and cover with normal coarse-grade bark or stone mulch so that they're not visible. The idea is, after a watering "event" by hose, rain, or thunderstorm, the inverted open-ended bottles would collect water, and the reservoir of water could slowly trickle into the soil. The sheer fact the open-ended bottles would collect and redirect water downwards versus the inevitable run-off during brief downpours and the aforementioned unwettable soil states, I think could be an advantage.
Any other techniques?