The plant will become dormant—and you want it to stay that way; it is the natural state. After the first deep freeze, put is in a room or place (garage) with no heat and natural light (window). You can add some water occasionally but this is not intended to be “watering”; the plant is dormant and will not take it up but the soil can be lightly moist. Bring the plant back outside when it shows signs of coming back to life. Plant it, per the guidance above, when the soil warms.
While your cuttings take root, keep them covered and moist. In a garden bed, a simple DIY mini greenhouse does the trick. Just place a bell jar, a garden cloche or an overturned mason jar over the cutting. A clear plastic bottle with the bottom cut out and the cap removed works, too. Water the soil regularly to keep it moist, but not soggy. Your mini hothouse will keep the humidity high inside.
Once you have had several weeks of below-freezing temperatures, cover the base of the rose with 12 inches of soil or mulch, and then cover the canes with straw, leaves, pine boughs or even foam insulation. Climbing roses can be wrapped right on their supports, or you can lay them on the ground and cover the canes with straw or brush. In severely cold climates, hybrid teas are sometimes partially dug up, laid down onto the soil, and the entire plant is then covered with more soil or mulch.
So grandma had the right idea in the first place, and she really did know what she was doing. It has always been fun to start roses from cuttings. Some people get their kicks by going "rose rustling" in the deserted cemeteries of old and forgotten mining towns. Others just take a twig from their favorite rose and stick it into the ground in their backyard. There is nothing complicated nor scientific about taking cuttings of roses and rooting them to "start" a new plant. There are various ways of taking rose cuttings, so let's tell you how.
Prepare a pot. Fill the small pot with potting soil. For the best results, replace a quarter of the soil with perlite, peat moss, or vermiculite, or a combination thereof. This will increase air flow and draining, giving your cutting a better opportunity to root. If the soil is dry, water it and allow the excess water to drain out, so that the soil is evenly moist.
Black Spot: Rose plant leaves with black spots that eventually turn yellow have black spot. This is often caused by water splashing on leaves, especially in rainy weather. Leaves may require a protective fungicide coating, which would start in the summer before leaf spots started until first frost. Thoroughly clean up debris in the fall, and prune out all diseased canes.
Be aware of your variety’s needs. Rose care will depend a lot on the variety you’re raising. Some roses like William Baffin and Lady Hillingdon climbing roses are more drought tolerant, for example, while others need more water. Some varieties can withstand less sunlight than others. Rose varieties should also be pruned differently depending on the variety and your climate area.
Taking rose cuttings can lead to a new crop of beautiful, successful roses. Like many other plants, it's important to choose a sunny spot for your rose cuttings that has moist soil. Cutting strong, healthy stems right above a set of leaves makes for great growing conditions, and dipping your cutting in a rooting hormone will help the roots take faster. By keeping your rose cuttings well hydrated, you'll have strong roots in no time.
Fertilizer: Roses are heavy feeders, and will benefit from a steady supply of nitrogen, phosphorus and potassium. You can provide these nutrients with either liquid or granular fertilizers, at a ratio of approximately 5-8-5. In most cases, regular applications of compost, rotted manure, fish emulsion and seaweed extracts will provide roses with all the nutrients they need. These organic amendments also help to moderate pH imbalances and stimulate beneficial soil life. Other organic amendments favored by rose growers include greensand, black rock phosphate and alfalfa meal.