It's 9/1/15, where has the summer gone! If you have or are thinking about putting up a season extension structure (e.g. high tunnel, low tunnel, mini-tunnel, caterpillar), now is the time to be putting in your plantings for winter harvests. There are many cold hardy crops that can survive the harsh temperatures of winter. Spinach and kale are two classic examples of crops that have been known to even overwinter outdoors under heavy snow cover or organic mulches. Plastic covered structures such as high tunnels create enough of a microclimate to ensure survival even in sub-freezing temperatures. Though temperature is a crucial factor in growth, light plays an even more critical role in developing crops large enough to be harvested in the winter months. The magic day length is 10 hours. Once day length reaches then goes below this critical span, crop growth is only significant for well-established crops. Banking as much crop growth (up to 75% of full growth) before this date is essential for harvests through the winter months. This date for most of Cook County is November 10th. I have put together a downloadable chart to help establish some planting guidelines for your garden or farm site. Remember, these are guidelines and not rigid dates. Each situation and microclimate is a bit different. Cook County has two different climate zones: Zone 6a and zone 5b, depending on your location relation to the lake. This may also effect these dates. However, this chart is a good place to start. Keeping records of when you plant and when you harvest will help fine tune these dates. Here is the direct link to the pdf. Download first, then print in landscape at 60-62% scale: