(but don't order your seed just yet - wait for the other categories to be discussed first)
So...last week we took a quick look at companion planting so that we could get an idea of how to begin to think about garden layout. With that floating in the back of our heads, let's dive into something else crucial - when to plant!
For some of us, it's getting to be about the time to buy seeds so that we'll be ready to start them. How do I know this?
Every area in the U.S. falls into several categories whaich are important for growing. All of them revolve around climate and they are:
USDA Hardiness Zone
American Horticultureal Society Heat Zone
The three work in tandem to determine what will grow where and when optimum growing times are.
The Hardiness Zones refer to the coldest temperature that an area will experience in winter. The zones range from 0a (-65 degrees) to 12b (55 degrees). The zone map
was released in 1990 and was based on 12 years of data ranging from 1974 to 1986. It represented a vast improvement over the original 1960 map because it was based on about twice as much data and divided each zone in half (i.e. a + b) for a more accurate representation.
In 2003, the American Horticultural Society, after collecting data for another 16 years, relaesed an update to the USDA map. This map relects increases or decreases in the zone assignments (and might show a bit of global warming...)
So...why not take a look here and find your zone! (Mine happens to be Zone 6 after the AHS adjustment is calculated in)
Ok - on to the next category - the Heat Zone. The Heat Zone map indicates just the opposite of the USDA Hardiness Zone. It tells the number of days in a year that are above 86 degrees (the temp at which most plants start to cook). This scale ranges from Zone 1 (1 day or less) to Zone 12 (more than 210 days) Where do you fall?? (I'm between 3 and 4)
Now that we have the extremes covered, what can we do with this info? Knowing how cold and hot it can get in your area will determine what types of plants you will be able to grow. For instance, if you love peas but you live in southern Florida, you'll have to really work your window of opportunity because peas like it cold. Just the same, if you love hot peppers and you live in northern Minnesota, you might need a greenhouse to heat things up.
To restate, the Hardiness and Heat Zones tell what we can grow.
There is another crucial component, however...when we can grow.
This is where the freeze/frost dates come into play. Since most of the U.S. gets cold to some extent, knowing when that cold happens is critical so that freshly set-out seedlings won't freeze. This is where the Freeze/Frost data comes in handy.
If you take a look here, you'll you'll be able to simply enter your state and retrieve a chart compiled with several years of data. Scroll to find your city/town and you'll see both the Spring and Fall dates (i.e. last frost of the winter and first of the fall) as well as the probabilities of occurance.
The reason that three temps are given (36, 32, and 28 degrees) is to reflect frosts, freezes, and hard freezes because some plants can tolerate frosts but not freezes, etc.
Take a look at your state and town and see where you fall (my date is about May 1st for 50% probability of 32 degrees). The probabilities are important when looking at the sensitivity of plants. Eggplant LOVES heat. One would want to be absolutely sure that any threat of late spring frost is over befor setting these plants out, so following the 10% probability would be a good idea. Lettuce is a little tougher so one could risk the 50% date outside or even the 90% date under a coldframe or row cover.
So...now you've got some info to help you get started. Here's how to think about your planning -
Step 1. What do you like to eat?
Step 2. How cold/warm does it get in your area? Check the Hardiness and Heat Zones.
Choose plants that you like to eat and that are listed as suitable for your zones.
Step 3. When is your last frost? Check the Freeze/Frost dates.
Tomorrow, we'll take the freeze/frost dates and figure out when to start seeds to make sure that they are good and strong when you set them out into the garden.