Flowering quince, often called Japonica, is a deciduous shrub with a round shape that will grow to a height of about 6 feet. It blooms in early spring for a short, but dramatic display of color, but the blooms are replaced by berries that are delicious when turned into jelly. Once flowering quince is established, it will thrive with very little help. The easiest way to propagate a flowering quince is by taking a stem cutting.
Take a cutting from a healthy quince with a clean, sharp knife. Cut a stem about 4 inches long, with at least two sets of leaves. Carefully strip the outer layer of bark from an inch of the cut end.
Fill a 3-inch pot with good quality commercial potting soil. Set the pot in a saucer of water for an hour, or until the potting soil is wet clear through.
Use a stick to make a hole in the middle of the pot. Dip the cut end of the dogwood stem in rooting hormone, remove any leaves that will be under the soil, and plant the stem in the hole. Be careful not to knock off the rooting hormone.
Put the dogwood stem in a zip-lock bag and seal the bag. The bag will act like a miniature greenhouse, keeping the atmosphere warm and humid. Put the cutting in a warm place where it will get indirect light, but never put it in the windowsill because the light will magnify through the plastic and burn the cutting.
Put the planting container on a heat mat, if you have one. Although the cutting will take root as long as it's in a warm room, a heat mat will speed up the process.
Look at the soil every day to make sure it's damp. If the soil appears dry, open the zip lock bag and mist the soil. If condensation forms inside the bag, there is too much moisture, so poke a few holes in the plastic to provide ventilation.
Check after about a month to see if the quince has taken root. Look on the bottom of the pot to see if there are tiny white roots visible through the drainage hole.
Repot the rooted stem cutting into a 4-inch pot. Put it in a warm, well-lit place until you're ready to plant the quince outside. Don't put it in a plastic bag.