I am amazed with the effective protection of creating a garden microclimate. Water and stones (cement) are the most effective heat/cool holders added in a garden. For example, we put blocks in the front border of one of our gardens. This garden is also against the house where there is a stone foundation.We used these two “hardscape” objects to benefit the plants by holding the sun’s heat in the winter and the cool of the summer night a little bit longer into the hot day. Lastly, this garden faces the south, which is the most winning exposure for the more delicate winter garden crops.
Yes, we do have mild winters in an 8a climate zone. However, even our Kalanchoe could be challenged by 28 degree nights. Its garden placement here keeps it safe when the temperature drops. Plant growth stalls when temps drop but growth happily resumes when the weather is more agreeable again!
One exception to this rule are the Mediterranean herbs of Greek oregano and Blue Tuscan Rosemary that grow in “mammoth mode” summer and winter! I guess they like their southwest facing garden with the cement block foundation in the back of them.
It works in reverse for the cold weather crops. When we planted the kale on a north facing wall, the stones held the cooler night temperatures longer into true day. This cooler exposure protected the kale from bolting prematurely.