Quit with the fertiliser. It's like feeding a baby on steak.

Did you move them from indoors to outdoors? If so they should have been hardened off.

I'm amazed they grew from cuttings since January. How did you do it?

I went on ahead today and snipped the still-soft and growing tops of the rosemary and put them in seed starter to try to grow them as cuttings again. I checked the roots of all my rosemary and all are brown and appear to have been burned by the fertilizer. They have all been indoors the whole time. I was not going to move them outside until the spring when I can harden them off and then keep them outside.

When I planted the cuttings in January, I just put them in what appears to be a top-quality seed starting mix that one reviewer who compared seed starter mixes said had almost 100% germination when he used it. I read on the back of the bag that it can also be used for rooting cuttings, so I used it. The company is called Coast of Maine and the seed starter mix is their Sprout Island Organic Seed Starter, if you want to check them out. They use lobster shell, kelp, and other organic leavings from the seafood and marine industries in Maine in their seed starter and other products. They suggested keeping the rosemary cuttings inside plastic bags (I used ziplock bags) that are mostly closed, with a little bit open for air circulation, while they developed their roots, then transplant them to pots with potting soil. So, that is what I did with the cuttings, then transplanted them to individual terra cotta pots with Coast of Maine's Bar Harbor Premium Potting Soil in them. I would say 80-90% of my herb and vegetable seeds have germinated and they and all of my rosemary cuttings have grown like wildfire with this seed starter and potting soil, but this is my first time doing all of this.

Might have rotted.

Here is a photo of what I did when I planted the cuttings and put them in the bags as the seed starter bag instructions recommended, floral_uk. I would see a lot of condensation/water droplets on the inside of the bag, so I didn't water them unless the soil dried out, but it usually stayed moist. The second photo is of the new cutting I just planted from the burned up rosemary. I think the ziplock bags basically turned into little greenhouses for the rosemary cuttings while they developed their roots. Then I transplanted them to individual terra cotta pots with potting soil in them from Coast of Maine. It all went south when I bought some plant food at a store and tried to feed them.

Hoping I can just start again with these new cuttings. We'll see.

gardengal48,

Could I add sand to the mixture (sand is plentiful here in the Sandhills of North Carolina!) to improve it or should I just start over with a cactus or succulent mix?

Start over with a better mix :-) Sand - even coarse sand - is too fine a particle size to provide much of an assistance in draining a peat based soil. You need something with a much larger size - perlite or pumice or granite grit.

I couldn't get my cuttings to root for life of me. Maybe a heat mat is needed? Try a longer cutting if you can4-6 inches.