For years, I've been using recycled solar cloches or hot caps made out of 2 liter bottles filled with water circling another plastic bottle with its bottom cut off in the center for the plant. I've used them to start tomatoes, zucchini, cucumbers, and other seeds up to six weeks before last frost. This year, I used them to overwinter a couple of kale plants and they worked just as well for that too. These simple devices can extend your growing season in the Spring and throughout the Fall and Winter.
This is one of the cloches I put out.
Here's the growing kale plant that overwintered in it.
Here's the second cloche without a bottle which broke over the winter.
Still this cloche's kale plant kept on growing.
A tomato plant volunteered in one of my ornamental planters inside over the Winter so I planted it out a couple of weeks ago in another recycled cloche.
The yellow color inside the plastic jug comes from tomato flowers. If they actually set fruit, I may finally have the earliest tomatoes in the community garden, but we'll see.
This week, I plan to remove the cloches around the kale plants and use them to plant zucchini and cucumber from seed here in USDA planting zone 6a.