Thanks for all the replies. I'm having trouble finding sprinkler heads with a spray distance that will work. I have seen that there are converters that will change your standard sprinkler head into a drip system. These seem like a cheap and easy solution to the problem, but how well do they work? Do they work with any standard irrigation system? My system allows for a maximum of 99 minutes per station. Will that be enough time for a thorough watering under a drip system? Or would I be better off just hooking it up to a hose (that would only work for one of the beds)?
With the drip system, since we're talking about one planting area, if you are not getting enough water from what ever drip stuff you install... you simply put in more drip equipement.
Of course, even in drip, you actually have lots of choises. You can use actual drip emmitters (where emmitters come in 0.5, 1, and 2 gph (gallons per hour) of flow rate. The total amount of water you get will depend upon which size emmitters you get and how far apart you space them. But then, beyond the basic "drip" emmitter is actual spray emmitters. They make little emmitters that send a spray in full arcs, emmitters with 1/2 arcs, 1/4 arcs. They usually get installed on top of a stake and the stake usually has a know that allows you to adjust the water (and therefore the distance) the emmitter throws the water.
The only MAIN thing to know about drip is that it requires a VERY FINE mess filter (because the smallest of particals can quickly clog the small opennings in drip equipment), and that it will all be designed to operate at pressures below 50psi. The reason for the 50 psi is because most drip equipment is designed such that you have a 1/2" thin wall pipe, and you install the emmitters by just punching a hole in the pipe and inserting the barb of the emmitter. At pressures above 50psi, the barbs can be pushed out of the 1/2" tubing.
There are plenty of ways to convert and existing sprinkler to drip, the main key being that you MUST have a filter and something to limit the pressure to less than 50psi. If you currently have a bunch of spray heads in the planter and want to convert to drip, you really just need one of these sprays converted to drip and cap off the rest (or ripe them out all together). Because once you get water to the bed, you get it from one side of the bed to the other with the 1/2" tubing laid on the ground (and covered with mulch) with the emmitters poked into the 1/2" tubing where ever you need the water.