Ask the master gardener: Winter sowing and growing in small spaces

Tips for creating your own mini-greenhouses using milk jugs, potting soil, and setting it in the snow with this relatively new alternative to starting seeds under lights.

By creating your own mini-greenhouses using milk jugs, potting soil, a little moisture and seeds, you can let nature decide when the seeds should sprout. Submitted photo

Dear Master Gardener: I keep hearing about winter sowing seeds. What is it and how do I do it?

Answer: Winter sowing is a relatively new alternative to starting seeds indoors under lights. By creating your own mini-greenhouses, you can let nature decide when the seeds should sprout. This works especially well for seeds that need to go through cold-stratification to break the seed coat.

Start by collecting plastic containers. Milk jugs work great — just slice most of the way around below the handle so you have a “hinged” lid. I prefer reusing bakery or takeout containers with clear lids that snap on. Poke holes in the bottom for drainage, as well as some holes in the lid to let some rain or snow in. Don’t forget a waterproof label! Then put a couple inches of dampened potting mix with no fertilizer in the bottom. Sprinkle your seeds on top, press them down slightly after sprinkling just a bit more potting mix on top. Snap the lid back on, or tape the milk jug closed with duct tape. Find a protected spot out of direct sunshine and set your creation in a snowbank!

As long as you see some condensation inside there’s enough moisture. If not, dribble some water down the inside edges. When the seeds’ genes determine it’s time to sprout, they will. Once you see the second set of true leaves you can slowly move the containers to brighter sun, open the lids on nice days, and pop the tops back on if it gets too cold overnight. Keep the containers watered.

Plants may be transplanted directly into the garden with no hardening off period — they are already accustomed to sunshine and wind. You can also plant the small seedlings into individual pots if you want to let them mature with deeper roots and more vegetation.


I’ve had luck with cool season vegetables like lettuce and spinach and seeds saved from some native perennials. If you try annual flowers, choose plants that have better cold tolerance like pansies or snapdragons.

Try winter sowing. It doesn’t take much time to put soil in a container you were going to recycle anyway, toss it in a snowbank, and get a head start on spring!

Dear Master Gardener: I live in a townhouse and don’t have space in my yard for a garden, but I have a patio. I would like to grow some vegetables in pots next summer. Are there small varieties that I can grow?

Answer: You will find when you look online or at seed catalogs this winter that more and more seed companies are selling small vegetables. The popularity in growing dwarf vegetables has risen because more gardeners want to grow food in limited spaces (small raised bed, hanging baskets, containers on decks, balconies and patios). Even without garden space you can grow substantial amounts of vegetables and herbs in containers. You have more control of the soil, light, water, and fertilizer levels when growing in containers instead of the ground. Just make sure the containers have good drainage holes.

Probably the easiest to grow in containers are baby greens, such as lettuce and spinach. You can start these cool season vegetables by directly sowing them in your pot in spring. In a week or two they will sprout, then quickly reach a harvest size of 3 to 4 inches. Snip off only the largest leaves and you will keep your harvest going for several weeks. When the plants bolt, pull them out, and plant some more. Microgreens can also be grown indoors right now. Plant the seeds in a soilless mix because soil and soil-based mixes are usually too heavy and dense, which can prevent your container from draining properly. Then, add water and place on a sunny windowsill or under grow lights. In several weeks you will have fresh greens for salad!

You can find miniature varieties of many different vegetables and they do well in containers because you can space them closer than their full-size counterparts. There are mini carrots, peppers, radishes, zucchini, beets, bok choi and cherry tomatoes. There is even an 8-inch diameter watermelon called Sugar Baby. Micro-Tom Tomato, developed by the University of Florida, is the perfect cherry tomato variety for growing in a tight spot — even a hanging basket — as it grows only 6 to 8 inches tall and produces lots of small, flavorful, cherry-sized fruit in about 60 days.

I’m sure you’ve seen miniature bell peppers in the grocery store. They too can be grown in containers. Miniature red bell peppers (there’s a yellow version, too) are short, stocky plants covered with 2-inch long miniature bell peppers with excellent flavor. Miniature basil is an Italian-style basil that does well in a window box or any container as the plant stays under 12 inches in size. Basil seeds need to be started indoors four to six weeks before the last frost. Eight Ball is a tiny round zucchini, Little Chicago beets are about the size of a golf ball, and Peter Pan pattypan squash is only 2 to 3 inches across — they are all great on the grill. You are definitely not limited by space when it comes to growing delicious vegetables!

You may get your garden questions answered by calling the new Master Gardener Help Line at 218-824-1068 and leaving a message. A Master Gardener will return your call. Or, emailing me at and I will answer you in the column if space allows.
University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. Information given in this column is based on university research.
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