Plumbing – How to connect to an unthreaded galvanized pipe stub for a garden hose

You branch off from the copper tubing with a 1/4" compression tee. Cut out a small section of tubing for which the tee replaces. You must use a tubing cutter to do this, any other method will cause the tube to become oval.

Install the short piece removed on the side outlet of the tee. Attach a 1/4" compression x 1/2" pipe thread adapter to the short section. If you can find a tee with a pipe thread side outlet (preferred), skip the previous step.

Connect a 1/2" pipe thread to hose adapter. When buying parts, ensure the male and female parts mate correctly. If you can't find the proper mates, get a short nipple or coupler to change gender. Use several layers of teflon tape on male pipe threads, wrapped in the direction that causes it to get more snug when the pipe is screwed in.

Attach hose and controller. After all this, there probably isn't much pressure left, meaning you could probably transition from hose to 1/4" drip fittings for the run from controller to plants, keeping the installation less obtrusive. If you use pressure adaptive drip fittings, you can better regulate the flow to each plant, otherwise the first plant will get the most water, the last hardly any.

Be careful, though unlikely in this case, as high pressure can cause drip fittings to blow apart. You also can't use most pressure reducers, as they can spill water as they function. You'll probably have to go from hose to 1/2" drip main to 1/4" drip distrubution. The 1/2 to 1/4 punched connection can leak slightly, so it should be done over the first plant.

Check at a hardware store. They often sell a bag of faucet washers of a mix of sizes that can be used to repair your faucet. You pick out the one from the kit that suits your faucet.

Sometimes the hardware store will have a whole section of individual faucet repair parts. Take the faucet washer and stem seal with you to match them up with new parts.

On the other hand the garden faucets probably are available in only so many styles. You could take a picture of your existing leaky faucet and take it along with you to the hardware store or other big box type store and purchase a new one of the same or very similar style. Then take it apart to redeploy the rubber parts from it for use in your old faucet.

Added Information:

I have actually repaired a faucet that was an outdoor spigot type in a unique way. It's valve stem piece was very corroded and logically led to the conclusion to replace the whole faucet. Unfortunately I found that the faucet was soldered onto a pipe inside the wall behind a stucco exterior and no direct access from the inside of the wall either. I took a sharp focused picture of the faucet and traveled off to the big box store and happened to find a full new faucet that was identical in every way to the old faucet. I was able to re-use the stem, top portion of the faucet body and the packing nut from the new faucet on the old lower portion faucet body and restore to like new performance without having to break any stucco or tear down a blind inside wall.