Though the calendar says winter has just started, we know that we have had two significant winter storms before official winter arrived. Long term forecasts are for a colder than normal January, February and March. This may be a good time to discuss techniques for extending the growing season. Most Pacific Northwest gardeners practice season extension, but let’s look at how to plan for some simple ways that will pay off for the home gardener.
The usual way to get gardens started earlier in the spring is by having lots of little transplants to set out as soon as the soil warms to 40 or 45 degrees. Lettuce, broccoli, cabbage, choy, celery, chard and kale are typical to start early in trays indoors. Use a sterile seed starting mix with some peat in it for good results. I have tried to make starting mix with compost and have had trouble with “damping off” disease, especially for the Brassicas. Wash your trays with a solution of water and bleach (10:1) to prevent fungal and bacterial diseases. These seeds like 55 degrees to germinate, but then can grow in 45 degree or even less. Either get a grow light stand (simple florescent tubes are good enough for seedlings) or make room on a south facing window with full light. Sometimes it is too cold to germinate seeds on the window sill, so place them on top of your refrigerator or by the furnace to stay warm till they sprout. Then move the tray to the window. After 4-5 weeks when the seedlings have 4 true leaves, it is OK to transplant to a nutrient rich potting mix with plenty of compost. I use lots of 4 inch plastic pots for transplanting. These pots don’t have to be washed, though some pests may be hiding in them, so keep a watch out. Then I usually keep the trays in a cloche or hoop house, which is a great addition to any garden.
Hoop houses have become very popular because they control the micro-climate so well. This is a large, temporary, plastic covered “greenhouse”. Often they are made with plastic pipes bent in a large hoop shape that the clear plastic skin is easily pulled over. The size depends on how much space you have. Typical hoop houses are 10 feet wide and 6.5 feet tall, which uses 18 foot lengths of schedule 40 PVC pipes. This is a comfortable height for me to work in, and the length depends on your needs. We started with them about 20 feet long. The other determining factor is the width of the plastic you are using to skin the frame. We bought a cheap construction grade the first year and that is just how long it lasted, one year. All that waste too. So, we purchase at least a 5year plastic now, either searching online or shopping at Steubers Greenhouse Supply in Snohomish, WA. The doors at the ends of the greenhouse and the framing that keeps it from lying flat in a wind may be complicated to bulid. A good door and frame design is available online through WSU Extension at http://cru.cahe.wsu.edu/CEPublications/eb1825/eb1825.html
What I like about hoop houses is working in the soil, not in pots on tables. Leaving trays on the ground in a hoop house gives them added protection from freezing weather, but watch out for slugs. After April 1st when the seedlings are transplanted out in the garden, start planting tomatoe and pepper starts or even the squash family in the hoop house. The one draw back is that these summer fruit bearing crops need pollinators and sometimes bees can’t get into the hoop house. Try these tricks : transplant a yellow flowering broccoli plant (left over from last season) by the open door of the hoop house, or catch a few bumble bees and release in the hoop house or just pollinate by hand by flicking the tomato blossoms. Some new varieties of tomatoes and cucumbers set fruit without pollination, listed in seed catalogs as “greenhouse varieties”.
Gardeners have developed cloche designs for many years. Cloches are smaller clear plastic or glass forms that cover a plant or a row of plants. I’ve used a lean to frame of old windows tied down to a few stakes. Permanent cold frames are popular to keep trays of seedlings in or grow and early crop of greens, but watch out for slugs in theses. Be careful though because panes of glass break, and it is difficult to get all the pieces out of the soil. Long sheets of clear plastic tunnels are being used more too. They just need to be anchored in our windy climate and need to be vented on sunny days. Let us not forget the microclimate benefits of floating row covers like Remay. It doesn’t need staking and it prevents flying pests. Remay offers only a 3-4 degree increase in temperature, but that is often enough for seeds to germinate early, especially carrots and beets
Which ever season extension techniques you want to try this year, you may have lots of snowy days to ponder, design and collect materials for your project. It looks like a tough winter. Eat lots of vitamin rich soups and stay warm and healthy.