Cover crops have a lot of benefits, but winter hardy cover crops can become weeds if you don’t till them into the soil at the right time of the year. Additionally, since cover crops need to be planted early enough in the season to allow them to grow before frost, they can reduce the amount of vegetables that you grow in your garden. Some gardeners may prefer to succession plant cold hardy veggies into autumn, while other gardeners may feel that they get more benefits out of cover cropping.