This is an excellent question, and one I didn't really really pay
attention to when I first pulled out my shovel. I made the raised
beds parallel to the slope with no drainage option, mostly because you
want raised beds to be flat on top, and it's much easier to make them
flat if you build parallel to the slope.
Since reading Eric's comment, I've been keeping my eye on the beds and I've been pleasantly surprised to see very little water
building up in the aisles between. Granted, it's been
relatively dry here (you know, an average of only about half an inch of
rain per week), so the groundwater isn't terribly high. But my sky
pond is still about halfway full, despite the fact that Lucy thought
there was some kind of critter in the drainpipe from the roof and ripped it to shreds
a couple of months ago, meaning only groundwater is recharging the
pond. (I really should fix that....)
Barring extreme waterlogging in my new gully beds, I figure I'll just
plant with the water in mind. For example, I discovered this
summer that the watermelons planted in a raised bed above some very
soggy soil did much better than those in the main part of the garden, so
those would be a good choice for our chinampa beds. And for all I
know, next year will be as dry as this one was wet, and I'll be glad
for every ounce of water retained.
Or maybe I'll change my mind and add some drainage! Only time will tell.
By the way, I decided not to bore you with a full-blown advertising post, but did want to alert you to the new sale on our chicken waterer website
--- I hope it makes your holiday shopping easier! Cold weather
has been keeping me inside, so I'm also making changes to my email lists
--- please stay alert and click to confirm that you want to stay on my
lists if you see an email from me in your inbox. Thanks for
bearing with the marketing interruptions!
I am happy to hear that the beds seem to be working well without drainage!
Have you thought about trying some hugelkulture beds further down the gully? I read in another blog somewhere about using rotten wood in a standing position, as opposed to laying it horizontally. They claimed better results. I sense an experiment waiting to happen....