Whether you got your roses from a florist or a neighbor's garden, you can grow a rose bush from a cut rose. The technique creates a hothouse for the rose to root. It will take several months from the time the rose is set in the mini hothouse to when it can be planted in the garden. Starting them in the fall allows the rose to develop a good root system, meaning it will be ready to be moved to the garden in the spring, after the threat of frost has passed.
Select a container for the rose that measures at least 6 inches in diameter. If it does not have drainage holes, drill several in the bottom or put 1 to 2 inches of clean sand in the bottom.
Pour good quality, sterile potting soil or vermiculite into the container, filling it about ¾ full. Tamp the soil gently.
Choose a fresh rose that is about 10 to 12 inches long with several leaf sets. If the rose is from a bush, select one whose bud is fully opened, but not faded. If the rose is from a florist, it must be rooted within a day or two.
Trim the bloom off the rose and pull off all but the top two leaf sets. Snip off the bottom of the stem and use a sharp knife to make several vertical slits, about ½ inch long around the stem. Dip the cut end in root stimulator.
Stick the pencil or your finger into the potting soil, to make a hole that is about 5 inches deep. If you use some other object, make sure it is clean, to prevent transferring bacteria to the potting soil. Insert half of the cut end of the rose in the hole. Push the soil around the stem and tamp down gently.
Pour water around the rose, drenching the potting soil or vermiculite. Place the pickle jar over the stem; avoid damaging the leaf sets. If you use a 2 liter plastic bottle, cut one end at the widest point, to create a tall dome. This is the mini hothouse.
Move the mini hothouse outside, placing it on a north-facing wall. Select a site that will shield the mini hothouse from direct sunlight, such as behind a shrub or other large plant or object.
Check the mini hothouse once or twice a week, especially if it is in a spot where it might get knocked over by wind or animals. Water the potting soil only if there is no condensation inside and the soil is completely dry.