Question
I'm sure there is a way to do this: Let's say someone gives you beautifull roses for your birthday, you can't help wanting to have such beauties grow right in your backyard, you notice a rose with a new branch growing out of it's stem. Now my grandmother used to cut that piece of the stem, then i think she put in pot, and cover it with a glass jar. Now back then we lived in Russia, now I live in California, but so far that technique although semt to work, eventually didn't, so I'd like to know the proper technique.

Thanks for your help.

Darya

Answer
Your grandmother had an excellent way to grow a cutting. In her country florist roses could also grow in the garden. The only difference is that now roses are so over bred that many times her method doesn't work. Also bear in mind that a florist roses are pampered in a greenhouse and most times won't survive in a garden. The florist rose is grown for thick petals so that a lot of handling won't damage the blooms. By the way that is the reason most florist roses don't have a fragrance because the petals are very thick. If you see a new cane starting from the rose, here is a variant of your grandmothers method.
Get a large pop bottle and cut the base out keeping the screw top.
Florist roses are varieties that grow well in a cool greenhouse. They do not make good looking blooms outdoors as they are damaged by rain, wind and also the flowers burn in the sun. They are not winter hardy as these roses are chosen to make loads of blooms indoors but look pathetic in the garden. The chances of them rooting are very slim indeed. Here is how to make a cutting from a florist type rose. Make sure that the rose is a fresh one. Ask the store when their roses come in and buy it the same day. A rose that has languished in the cooler will not root.
Adding half sand is a good idea. Wet down the mixture. Make a couple of vertical slits in the base of the rose cane so frail new roots can purh out easier. Make a hole with a pencil and carefully insert the cutting firming the soil around it. Place the large pop bottle over the cutting and screw top on. Then place in a cool area as roses will make roots best when the temperature is between 40' and 60'. When you see leaves forming, take the cap off, plus the bottle  during the night and replace during the day without the cap. Finally when the plant is starting to really grow take the bottle off completely. Fertilize using a half strength house plant type like Schultz. If the rose has good vigour then you will be successful but if it lacks vigour you may have problems so don't blame yourself if it won't take.
Hope this helps. Lynnette