Thanks for this. What has stopped me from going down this route is that a large part of my irrigation network is old steel pipe which is not suitable for carrying fertilizer enriched water (due to corrosion issues). If, one day, I manage to replace these, I will install an injection pump downstream from my pressure pump. This will also allow me to correct the pH of my irrigation water by adding acid to it.

The truth is, I only fertilize my roses once a year, counting on mulch and compost to supply anything else. Feed the soil, not the plant. Of course, my soil is a sandy clay, and clay holds on to nutrients. If I had a soil that had less clay in it, I would probably need to fertilize more frequently and might be looking for a system like this. Or if I grew roses for exhibition I might feel compelled to use more fertilizer. But I don't, so I don't.

As it is, once I finish the winter pruning (in California we prune roses in the winter), I spread a granular organic fertilizer, then water, then cover with this year's new mulch. It there is old mulch left on the ground from the previous year, I count on the watering to wash the fertilizer down to the surface of the soil.

And that's about it. Could not be easier.

My fertilizing regime is much like Rosefolly's. All roses get bagged cow manure when they show the first signs of life in spring. I ordered 15 70-litre bags (equals about 16 gallons per bag I think) in March and 7 bags of bark mulch. This is for the whole garden, not only the roses. My aim is to give reblooming roses a dose of whatever pelleted or liquid fertilizer I happen to find, some cheap brand, in early summer but before the end of July. But I don't always find the time and many years I trust my heavy clay soil to be rich enough especially for larger shrubs. I take more care with polys and floribundas.

As a further aside, this is the same concept used by garden centers. You know when you stroll through and someone is always busy watering all the plants? Well, that isn't just water. They also use a fertigation system that injects micro quantities of fertilizer into that water. That's what keeps those hanging baskets looking so good!

I have a drip irrigation system, and was doing this for years when I was heavily into exhibiting.

clarion2, that and plant hormones. You can control blooming time and bloom quality, growth, internodal length and lots of such things with these..