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To irrigate a standard 4 x 8-foot raised bed, you'll need to purchase two 10-foot lengths of half-inch PVC pipe, plus four right-angle couplers, one tee (3-point) coupler and one double-tee (4-point) coupler. Also, you'll need a 5/64 drill bit to perforate the tubing. The couplers provide such a snug fit that you won't necessarily need to buy PVC bonding compound. That way you can knock the assembly apart for winter storage.
Once you've got the rig assembled, find an old length of garden hose, chop off the male end and slip the stub over the entry tube. A 50-cent tightening hose clamp will provide a leakproof connection. There's a commercial version of this setup that will allow you to thread a stock ¾-inch hose connector directly onto their system. That sells for $24.95. Gardeners Supply Company markets something similar that is suitable for irrigating 3-by-3-foot raised beds, and that's selling for $16.95.