Making a Mini Greenhouse from Reused Plastic Spinach Containers

I just had to laugh the other day while reading It's Not Easy to Be Green, a blog written by friend and fellow "green" blogger, Jennifer. In her post about Tiny Houses, she discusses environmentally-correct compromises and how it can be difficult to make the right decisions. Jennifer mentions that while shopping, she "can’t decide between the organic spinach in the plastic box or the loose leaf conventional spinach that can go in a reusable bag ." This is the part the part that made me laugh because the spinach bag vs. container has been a similar dilemma of mine for years.

Due to financial restrictions, I do not buy the local loose-leaf spinach from the Co-Op. Like Jennifer, I have to make compromises. Although I buy many local, organic vegetables, I choose to grow my own spinach and lettuce in the Summer, but purchase imported spinach during the Winter. I'm sorry to admit that I'm far from being a true locavore, but fresh salad is my all time favorite food and I can't imagine going a Winter without it. My grocery store offers pre-bagged conventional spinach or organic spinach in a large plastic container. For years, Mark and I bought the bagged conventional spinach because we thought the large plastic containers were outrageous and waste more materials than the bags. This year, however, I've decided that the containers are probably less impactive than the bags for three reasons: 1) they are made from recycled plastic, 2) they can be reused as containers for storing things, and 3) they can be recycled, whereas plastic bags cannot. But mostly, I want to buy spinach in plastic containers because I want greenhouses for starting my seeds!

One of my gardening goals this year is to try to grow and store as many tomatoes as possible. Growing tomatoes in the heart of the Rockies is challenging and tomatoes have never been a strong crop of mine anyway. Since the last frost in Bozeman is traditionally Memorial Day weekend and first frost could be anytime in September, this means a very short growing season for sensitive plants. Plus, since I technically live on a high desert, Summer nights are usually pretty chilly. Tomatoes don't like cold nights.

I've noticed that in addition to insulating tomatoes plants with Walls of Water, the key to growing tomatoes in Montana is to grow them as big as possible indoors before setting them out in the garden. Most folks buy very large tomatoes to plant in their gardens. I'm not talking about the 6 inch tall seedlings that come in 6 packs. I'm talking about the mature, 12+ inch plants that are sold in deep tubs. These large tomatoes are grown in commercial greenhouses and cost any where from $5 to $20+ each! I can't afford mature plants, so this year, I'm starting tomatoes from seed myself. Although the seed packet instructs to start tomato seeds 2 months before last frost, I started mine on January 30th, so that's 4 months in advance. Hopefully they'll grow big and strong in my apartment before I set them outside.

To make a mini greenhouse for starting seeds, you'll need two large plastic spinach containers. Spinach and lettuce containers come in all shapes and sizes and any shape and size works, as long as you use two that are the same. I filled one container 3/5 the way up with seed starting mix. I didn't punch holes in mine for drainage, so I have to be careful not to over water my plants. You can punch holes in yours if you'd like. I planted 6 seeds, watered the soil lightly, put the lid on the container, and placed it in a sunny, south-facing window. When the seedlings where almost touching the lid, which was today, I removed the lid and placed another container upside-down on top of the container with the soil and seedlings. I carefully cut away the rim of the upside container so that it fit into the rim of the bottom container. The tomatoes will now have a warm, moist growing environment until they are about 6 inches tall. When that happens, they should be healthy enough to grow in the container without the lid. At a certain point, I'll have to transplant the seedlings into larger, individual containers. Another option is to place the upside-down container on top of the bottom container at the beginning instead of temporarily using the lid. The lid can can be placed under the greenhouse to act as a drip pan, should you decide to punch drainage holes in your container.

I've grown various seeds in the exact same homemade greenhoues. Most any type of seed can be started indoors in a homemade mini greenhouse, except for seeds that prefer to be directly planted outdoors. Plastic seed starting greenhouses and flats are available to purchase from gardening stores, but why buy new plastic when you can reuse old plastic? If you do not buy spinach or lettuce from plastic containers, but want to make you own greenhouse, I recommend picking through your local recycling dumpsters for discarded containers. This is how I scored a few plastic containers last year for making my own greenhouses.

By, the way, I'm growing three heirloom tomatoes varieties that are supposed to mature the quickest and be most cold tolerant. They are Glacier, Oregon Spring, and Honeydrop Cherry. I'll continue to blog about their growth and production over the course of the Spring and Summer to let fellow Zone 4 gardeners how they work out.