Greenhouses help you lengthen the growing season. You can enjoy flowers and vegetables for much longer, without much more effort. You could begin with a plastic dome to protect seedlings from the cold or you could go with a full-size greenhouse. You could try starting your seedlings indoors in early spring. A mini greenhouse kit has special lighting to start healthy growth. When your plants have reached a few inches high, it's time to transplant in the garden.
Next you could move on to a mini garden greenhouse with a frame. It will protect young plants from cold nighttime temperatures. Another option is a lean-to grow house that sits against a wall. It uses little space but houses several plants. There are portable greenhouses that you can take down in winter. These are easy to move around the garden. Once you've become a serious gardener, you're ready for a permanent greenhouse with a door. Plants can be grown inside one of these all year long.