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Become a Smarter Gardener in 2019: Start your seeds early with 'winter sowing'

I’m looking outside at the piles of snow that February 2019 has brought!  As a gardener, I am highly motivated to attempt a fun method for starting plants outside (yes—outside!) for the spring.  It’s called “winter sowing.”

Turn a milk jug into a mini-greenhouse

How about it—a growing season longer than 4 months??? All it takes is a milk jug, a ruler, a sharp knife, magic marker, plastic labels, some potting soil and seeds.  This method is typically used to give your vegetables a good start--it's great for cool season veggies in particular like kale and spinach. UMN Extension Master Gardener Theresa Rooney says annuals and perennial seeds also work just fine. However, she's found that seeds for more tropical plants will not grow.

Easy step-by-step instructions

Here’s the “how-to” info:
  1. Make your mini-greenhouse by taking a plastic milk jug (the see-through kind) and cut the jug in half—but be sure to leave a 1" hinge under the handle. Also, leave room for 2 inches of soil at the bottom plus an inch. Good to measure it with your ruler.
    (Extension Master Gardener Theresa Rooney has a good tip—if you’re not a milk drinker, you can find used milk jugs at your local coffee shop.  You won’t need the cap.)
  2. You will be growing one kind of seed in each container.  Create a waterproof ID label on a popsicle stick or plastic stick for inside the jug.
  3. Take the lid off. Add 2 inches of potting soil in the bottom, plant your seeds and add the label.
  4. Water it well—make it so wet it looks like mud. Don’t drain yet. 
  5. Duct tape the two halves together. And write what it is on the outside of the jug. 
  6. Take it outside and with a sharp knife, poke holes in the bottom so the water can drain out.

Where to put it?

The next step is finding a good spot for your mini-greenhouse. You’ll want to put it anywhere but the southwest corner of your yard. Avoid the winter sun—believe it or not, it’s too hot for your little greenhouse! Instead, hide the jug under a bush, a picnic table or next to your garage.

Won't it freeze?

  Yes, the jug will freeze, of course, and that’s okay.  Once it starts to thaw in the spring, check to see if your soil needs water. Usually, water from the snow and rain will be enough.
If the temperatures outside are warming up, lift off the lid.  If it’s cold or we have ice or snow, put the lid back on. The jug top will protect your plants from rabbits, so keep an eye out for them.

When spring arrives, you can take the little plants out and pot them up. They’ll grow until you’re ready to plant them in your garden.

For more information on winter sowing, go to:
https://extension.psu.edu/successful-winter-seed-sowing

The Permaculture Research Institute also has information.

Author: Gail Hudson, Extension Communications


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Comments

  1. what should be the distance between seeds for growing in a mini-greenhouse like this?

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  2. The question here really is--how many seeds should you plant? It depends on what size seedlings you want as a result, and the size of the mature plant. So tomatoes, for example--you might want 4-6 plants in a jug. Kale, maybe 5. Microgreens--plant lots! Also consider that you'll have to pull the seedlings apart and re-pot them. By the way--not all your seeds will germinate. Good question--thanks for asking!

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