While it seems to make sense that your plants will grow more easily in a greenhouse, it might be nice to know exactly why that is!
When the sun shines on a greenhouse, the light is absorbed and divided over your greenhouse as heat energy. Glass, polycarbonate or foil is transparent for visible light and short wave light. The sunlight is being absorbed by the material of the greenhouse, the soil and the plants and is being transformed into heat energy. The materials that are being heated will transmit a long wave heat radiation and that’s how the temperature rises in a greenhouse.
While this explanation might be quite technical, it’s no different to how a room will heat up when the sun is shining on it. Because the greenhouse is made entirely out of glass the effect inside will be much larger than in a room with one or two windows. The heat and light will give your vegetables and flowers the energy they need to grow.
Next to the sunlight warming up the greenhouse, your plants are protected from outdoor challenges, such as frost, wind, rain and thunderstorms. Your plants are nice and safe in the greenhouse and you don’t have to worry about a sudden storm to ruin your crops.