There are quite a few options out there depending on the size of your garden. For most gardens with rows less than 100' long, a 5/8" mainline tubing and the fittings listed below will work perfectly. If you have rows longer than 100', then you have to upsize to a whole new category of fittings. As such, I'd recommend trying to keep your rows less than 100' long if possible.
Below we've listed all the necessary components (with links) of a drip irrigation for an in-ground garden. This checklist includes the filter, pressure regulator, mainline tubing, drip tape, and all the fittings you would need. Once you have all these pieces, you can successfully install a drip irrigation system in your garden.
3/4" Hose Thread Filter - This filter will serve as the beginning of your drip irrigation system. The filter catches any hard particles or debris that could possibly clog the drip tape. This particular filter has 3/4" hose threads so that your water hose connects directly to the filter without any additional connections.
Senninger 3/4" Hose Thread 10 PSI Pressure Regulator - Any drip tape irrigation system requires a pressure regulator to operate the tape properly. If the pressure is too high, it will burst the drip irrigation lines. This 10 PSI pressure regulator has 3/4" hose threads so that it easily connects to the filter above.
Irritec PermaLoc Tubing Tee with Female Hose Threads - This fitting connects to the white end of the pressure regulator via the 3/4" hose threads. It then splits into a tee so that you can install it in the center of a plot for more equal water distribution with your drip system.
Poly Mainline Tubing - Also called "supply line," this is the feeder line for your drip irrigation system. This 5/8" tubing will extend along the width of your plot. Individual drip lines can then be connected anywhere along that stretch of tubing.
PermaLoc Mainline Tubing End Cap - This fitting terminates the mainline tubing at the end of each plot. It also has a convenient, screw-on drainage cap that makes it easy to flush the mainline tubing. You'll need two of these for a basic garden plot.
Mainline Tubing Hole Punch - This tool is used to punch holes in the mainline tubing for installing drip lines. There are lots of different hole punch tools on the market, but this is by far the best one we've ever used.
8 mil Drip Irrigation Tape - This is the preferred drip tape at Lazy Dog Farm. This P1 drip tape is durable and usually lasts us several seasons. We prefer the 8 mil tape with 12" emitter spacing, but there are a wide variety of options for each gardener.
Drip Tape Row Start Fitting - These fittings connect the mainline tubing to the drip tape. You'll need one of these fittings for each row you're going to have in your garden, so keep that in mind when ordering.
Drip Tape Row End Fitting - These fittings terminate the end of the drip tape by crimping the tape. Much like the row start fittings, you'll need one of these for each row you plan on having in your garden.