Covering plants for the cold weather in the CZ?

DO NOT use horse manure. It can be too strong for the plants. See if you can find a good mulching material - here in the Southern US we use pine straw. Hay or a heavy layer of organic material like the leaves would also work. Some people even use layers of newspaper as mulch for plants to protect them during the winter. Leaf mold (rotted leaves) also would make an excellent mulch for your plants. If you have a garden center check with them to see what they recommend locally. Good luck.