Update on the Winter Sowing Containers

winter sowing containers
Lots of germination; lots of rain.

I wrote some time ago about starting native perennials in winter sowing containers, and thought now would be a good time for an update.

Given our horrifically long winter, the plants in the containers are still pretty small. The good news is, germination occurred in almost all of the 28 containers. The two that have not germinated yet — and I do not expect them to — got pretty water-logged and the seeds may have rotted.

Because of the long winter, I did not end up following the usual winter sowing procedure. Normally, winter-sowers will put their plants out sometime during the winter and leave them there until it starts to warm up. Gradually, they will open the containers up, closing them at night to keep the plants warm. Minnesota springs are not usually gradual and this one was light-speed. On May 2, we had about 10 inches of snow on my garden and a temperature around 28. On May 14, the temperature flirted with 95. (Are we crazy to live in this climate? Very likely.) In any case, once it started to warm up, I just took the covers off of the winter sowing containers and called it a day. Of course, since then, it has been cooler, grayer and pretty wet.

I’ll let the plants get up to size and then, over time, transplant them out to the meadow where they will add color to the grasses and other plants I purchased from Prairie Moon Nursery.

My experiences with winter sowing have always been mixed. It does work — no question about it — but it does not work as well as starting plants under lights. It’s great for a situation like this one: I want a lot of plants and I want them cheaply.

What’s been your experience with winter sowing?



How to Winter Sow Wildflowers

winter containers outside
Lined up in a partial sun area, these containers are patiently waiting for spring.

As part of my big project for 2013, I’ll be using winter sowing containers to grow several kinds of wildflowers from seed. Wildflowers lend themselves very well to winter sowing because many of them require cold stratification, which is a period of chilling prior to germination.


For winter sowing, you need the following items:

Clear plastic containers, at least 4 to 6 inches deep. (I like gallon milk jugs, but some gardeners swear by those large lettuce or spinach containers or 2-liter soda pop jugs.)

Potting soil (Your choice on brand and type. This year I am using a homemade mixture of two parts each peat moss and vermiculite and one part worm castings. This is a recipe I picked up from one of my favorite garden blogs. You have to listen to the podcast to get the full recipe, but it’s basically 2-2-1.)


Equipment to poke holes in and cut plastic jugs (such as scissors, awl, pruning shears or soldering iron)

Duct tape

Markers, something to write on (popsicle sticks, old blinds, etc.)


1) Wash the containers well in a 10 percent bleach solution. Rinse.

soldering iron
A soldering iron makes quick work of creating drainage holes in the winter containers.

2) Poke several holes in the bottom of the container for drainage and a few in the top to allow rain or snow to drip in. I’ve used scissors in the past, but after seeing a recommendation here, I bought a cheap ($4 at the local big box) soldering iron, which is a breeze for poking holes. Be aware, however, that melting plastic stinks. I do this on the back patio. Also, be careful if you have children in the home — soldering irons get really hot!

container hinged
Container ready for soil and seeds.

3) Cut around the jug about 4 to 5 inches from the bottom, leaving the handle in place, so it functions like a hinge. For this, I poke a hole in the plastic with a pruning tool, then cut around with a scissors.

4) Put your potting mix in a large bucket and get it very wet. Give the water time to soak in, so you are sure you have a good, loose, wet soil.

5) Prop open the container and fill it with several inches of soil. Pat this lightly, then plant the seeds according to package instructions. Some seeds need to be immersed in the soil, others can just float on the surface with a little soil on top.

6) Write the name of what is in the container on a plant stick using a grease pencil (if you can find one) or a permanent marker. Also, write an identification on the outside of the container as well. DO NOT SKIP THIS STEP. You will forget what is in the container, if it is not marked. This year, I numbered the containers in multiple spots and lined them up in order, as a back up in case my markers fade.

7) Once they have been thoroughly marked, seal up the containers with duct tape. Some gardeners leave the caps on the jugs, some don’t. I have a few of each.

8) Set the containers outside and wait. As spring arrives, you will need to check the containers regularly to make sure they have enough moisture. When plants start to grow, gradually make the air holes on top larger and eventually cut the tops off the containers. Here’s a good video that shows you how the seeds will progress.

9) When you seedlings are strong and the weather has warmed up, plant them in the garden and enjoy.

The Meadow Project

meadow 2011
This is the area I’m hoping to improve this year, with more wildflowers and native grasses.

The biggest garden project I have planned for 2013 is to plant more prairie-style plants in the meadow behind my house, which runs adjacent to a city-owned walking path. While I planted wildflowers in it when we first moved out here, this area has become overrun with wild parsnip, giant ragweed and a few other real bad-boys of the plant world. I’ve undertaken some steps to remove the invasives and plan to replace them with grasses and wildflowers native to Minnesota. My hope is that this area will provide lots of nectar for butterflies and bees, seeds and nesting sites for birds and beauty for all the humans that pass by it each day.

I’ve ordered both plants and seeds from Prairie Moon Nursery in Winona, which is one of several outstanding native plants nurseries in our area. Why order both plants and seeds? Insurance — plain and simple. The plants will come in May, all ready to grow, having been started and nurtured by the pros at Prairie Moon. That’s great, but the plants are not cheap. Seeds, on the other hand, are cheap, so I’m hoping to get more plants at a lower cost by growing some myself.

sunflowers in meadow
Sunflowers have done well in my meadow, but I’m hoping to add greater variety of native plants.

Since most wildflowers require what’s called cold stratification, winter sowing is the perfect method for starting wildflower seeds. Cold stratification means that the seeds need to experience the cold of winter before they will germinate. I put out a call on Facebook for some milk jugs to use for winter sowing, and so far — thank to my friends Betsy and Marcia — I have about 25 jugs.

The idea behind winter sowing is that you create a little greenhouse for the seeds, by filling the milk jug with very wet potting soil, planting the seeds, sealing it up and putting it out in the cold. The seeds will freeze and thaw and refreeze as the weather moves from winter to spring. Eventually they will start sprouting, at which point you begin exposing them to more air and opening up the little greenhouses.

Tomorrow I’ll write more about how to set up winter sowing containers. Here are the seeds I’ll be starting in my containers:

Golden Alexanders (Zizia aurea)

Foxglove beardtongue (Penstemon digitalis)

Sweet Joe Pye weed (Euptorium purpureum)

Short’s aster (Aster shortii)

Nodding onion (Allium cernuum)

Butterfly weed (Asclepias tuberosa)

Rattlesnake master (Eryngium yuccifolium)

Common ironweed (Vernonia fasciculata)

White prairie clover (Dalea candida)

Spotted beebalm (Monarda punctata)

Meadow blazing star (Liatris ligulistylis)

What are your favorite prairie plants?