I use very nutritious potting soil, and let the cuttings get established before fertilizing. Then I use 1/2 strength Miracle-gro, BUT I water the plants first, and then fertilize an hour or so later - to insure that the plants are well hydrated. Fertilizing a dry plant is disastrous, and the more tender they are, the worse the disaster. Once they are established in a one gallon pot, I fertilize, still at 1/2 strength, but very frequently, often weekly. The majority of my cuttings this year are now plants in the 4-6 foot tall range.

If you measure the concentration of salts in your fertilizer dilution, you won't kill your plants anymore. It is easy, you can see here how calculate it:

www_firstrays.com/fertcalc.htm

For example, when I grow tomato seedlings (can you imagine anything more tender than a just germinated tomato plant?), I begin to fertilize with 50 ppm of N (in each watering), 2 weeks later I fertilize with 100 ppm of N and never a plant has died for this cause.

How a guide, if you don't exceed 200 ppm of N, hardly you will kill a plant. For tender plants don't exceed 150 ppm of N.

It is measured in ppm (Part Per Million)of N, it is supposed that the other salts (P and K) are in a proportionate distribution.

Usually, the commercial fertilizers, advise excessively high concentrations of salts, it is to facilitate the fertilizer application in a fortnightly or weekly interval, instead of each watering.

Taking into account all the above, how was the ppm of N of your diluted fertilizer? Maybe, the roots of your cuttings were excessively tender.

In any case, if you follow Pitangadiego advices, you will be right.