Cheap fertilizer injector mod
Hey guys, here's a little mod I put together so I could fertigate my ever growing collection of container plants. Wrestling with the watering can and teaspoons was just getting too time consuming. And the other cheap fertigation solutions out there (Ez-Flo, Hozon) have marginal reviews and seem difficult to dial in correctly, if they work at all. The Dosatron/Dosmatic route is the best, but at over $250 each, they're too expensive for the three areas around my house that need watering.
I'm using the Gilmour 362 sprayer ($18 Amazon) and a Melnor wand ($8 home depot). There's a number of Gilmour sprayers, but the 362 is the highest rated and built like a little brass tank. The ratio goes down to a single teaspoon per gallon, which is great for Dyna-Gro -- fill up a quarter to half the container with fertilizer and the rest with water and you're good to go. At the lowest setting, you'll get 100 gallons before needing to refill.
Also, it's easy to double check that the Gilmour is actually proportioning the fertilizer correctly. Set the dial to 10 and fill up a gallon jug. 10 tbs (5 oz) should disappear from the tank if your water pressure is a standard 50-60 psi.
The problem with the Gilmour is its nozzles -- either a flat 10' wide fan or a beam of water that'll strip paint. That's where the Melnor wand comes in. Just about any wand will work, though you'll need a hose thread adapter to connect the wand to the tube. I'm using 1/2" tubing from Home Depot along with metal screw clamps to tie the whole thing together. I'm sure one could rig up a nozzle directly to the end of the sprayer without the hose. If Gilmour strapped a watering wand on the end of this sprayer, it'd be the best hose fertigator around.