Getting a jump on the season

These days big box retail stores seem to rush us through the seasons. Nearly as soon as the Fourth Of July is over, store shelves fill up with Halloween and Christmas decorations. Then in late December, as Christmas decor goes on clearance, retail shelves begin to fill with spring garden supplies, such as garden seed packets and plant propagation equipment. In cold northern regions, like my home state of Wisconsin, you may feel like the seasons already rush by, without retail stores hurrying them along even more.

While shelves and shelves of garden seed, can be an exciting reminder that spring is on it's way, most of us in these cooler climates, are hesitant to start our spring garden seeds as early as January. If you do not have a greenhouse, you usually must resort to starting seeds indoors which takes space, careful observation and extra care. Starting seeds indoors can also require the continual use, and added expense, of running artificial light and heat sources. To save time, space and money, many frugal gardeners have begun to winter sow certain plants, rather than sowing them in controlled indoor environments.

Winter sowing is a process of allowing seeds to germinate outdoors, with mother nature alone controlling the temperature and light. Similar to starting seeds in greenhouses or cold frames, winter-sown seeds are generally planted in miniature greenhouses made out of clear or opaque plastic jugs. Got empty clear or opaque jugs from milk, juice, water or even kitty litter piling up? You can repurpose them into mini greenhouses for winter sowing.

What Are The Benefits Of Winter Sowing?

Besides saving space, time, money and repurposing plastic jugs, there are several benefits of winter sowing. Within the protection of homemade mini greenhouses, different plant seeds can be sown at different times, based on their cold hardiness, stratification needs and expected germination and maturity rates. For example, perennials and cold crops can be sown in plastic jugs and set outside as early as December or January, even in cool northern climates.

Because winter sown seedlings are grown outdoors, they are exposed to natural fluctuations in temperature, so hardening off is generally not required. There is no need to set timers or alarms to remember to turn on or off artificial grow lights or seedling heat mats, instead mother nature provides the necessary warm and light for seeds to germinate naturally. Because of this, many fungal or viral seedling diseases, such as dampening off, are avoided and these seedlings begin their lives much more hardy and resilient than plants started indoors.

These homemade greenhouses for winter sowing, provide insulation on cool late winter evening and protect tender, young seedlings from damaging frosts. If the weather is extremely dry, moisture can be added by removing the jug's cap and spritzing inside with a spray bottle. On unseasonably warm days in late winter, these miniature greenhouses can be vented by removing the cap or opening up their clamshell design, so young seedlings aren't overheated and essentially cooked.

Time your winter sown seedlings according to the weather

Like starting seeds indoors, winter sown seeds are times based on their specific plant needs. Though winter sowing is not appropriate for all plants, it is for many common garden plants. In January through February, winter sow perennials, cole crops such as spinach, kale, brussel sprouts, and broccoli, and herbs like thyme, sage, cilantro, oregano, dill and fennel. Hold off until March to winter sow annuals, tender perennials, lettuce, bok choy, beets, carrots and tender herbs such as basil and parsley. Tomatoes and peppers should not be planted outdoors until April. If in doubt about what to plant when, do thorough research on the germination and maturity rates of the specific seeds you are planting.

How Do I Winter Sow My Garden Plants?

To make these miniature greenhouses for winter sowing, collect and wash out 1 gallon or larger plastic jugs. 2 liter soda bottles can also be used, but it is recommended that you not use any vessel smaller than 2 liters, as the plants may not have adequate room for growth in small containers. With a Sharpie or other permanent marker, draw a horizontal line, approximately 1/2- 2/3 up the bottle or jug; this line will be your cutting guide. With a pen knife cut along this line, however leave one side of the jug or at least a 3" portion of the line uncut, so that the top and bottom of the jug are still connected by a side or portion of the plastic. This uncut section will act as a hinge to you can easily open up the mini greenhouses to check on the germination and growth process. The end result should be a sort of clamshell, you can use tape to secure the top half of the vessel closed after you have sown your seeds inside. However, before adding dirt or seeds to your miniature greenhouses, be sure to poke plenty of drainage holes in the bottom, and also poke about 2-4 small ventilation holes in the top half of the vessel.

Once you clamshell is created and all drainage/ventilation holes are poked, you can fill the bottom half of the vessel with potting media. Use an appropriate potting mix for the specific seeds you are sowing. Fill the bottom "clamshell" to a level about a 1/2-1" below the cut. Sow your seeds at the depths and spacing recommended on the seed packets. With an indelible ink marker, write the type of seed down and date on each mini greenhouse. Then secure the top half of the clamshell closed with a little duct or packaging tape. Find an out of the way, safe spot outside to place all your winter sown seeds. You'll want easy access to them to check on their progress, but you'll also want them out of the way of snow blowers, shovels or foot traffic. I usually line mine up along the edge of my patio, where they are out of the way and unlikely to be disturbed. Once a week check the progress of your winter sown seeds.