Formula for success - planting fall vegetables

August isn't really my favorite month. By now, I've had enough of summer heat and I'm anxious for autumn. And yet, I know that the respite that autumn holds, of colored leaves, cooler temperatures and visits to the local pumpkin patch will arrive and depart all too quickly, to be replaced by the bitterness of winter.

And so, August prods me to go outside.

The tricky part is trying to determine what can still be planted in August. Although it may seem far away, the first frost date is lurking out there in the shadows and needs to be taken into consideration for planting any cold sensitive plants, especially anything that produces fruit or vegetables.

Of course, no one can predict when the first frost of the season will actually occur. Sources such as the National Climatic Data Center, The Farmers Almanac, and Victory Seeds all list different dates for the average "first killing frost date" for DC. The earliest of which seems to be October 17th.....less than 60 days away. (Although a more accurate date is probably late October or early to mid November).

So now that we know that date, we can do a little math to determine what can still be planted.

I found this somewhat confusing formula on the Virginia Cooperative Extension website (as well as many other sites around the internet). I found it odd that none of them explained it fully and I have to admit I was a little lost. After looking at it a little closer, I've come up with my own explanation of what it is supposed to mean. The formula:

1. Number of days for seeds to germinate, if you grow your own from seed +
2. Average harvest period +
3. Fall Factor (about two weeks) +
4. Frost Tender Factor (if applicable; 2 weeks =
5. Days to count back from first frost date.

Here is the formula breakdown (as I understand it):

1) First, if you are growing your plants from seeds, you have to determine the average number of days for the seeds to germinate. Most seed packets will contain this information. It can also be found on many seed catalog websites. Here is a list I found on the Heirloom Seeds website.

2) I asked several "garden experts" I know what they thought "average harvest period" meant. To me, it was logical to think it meant the time from when a plant sprouts until when you can expect to start your "harvest". Other people thought it might mean the length of harvest period.

3) According to the University of Virginia Extension website "The Fall Factor takes into account the slower growth that results from cooler weather and shorter days in the fall and amounts to about two weeks."

4) "The Frost Tender Factor is added only for those crops that are sensitive to frost (corn, bean, cucumber, tomato, squash), as these must mature two weeks before frost in order to produce a reasonable harvest."

So if you take all of those numbers, add, subtract, carry the one, etc. you can probably determine what you can still plant with the hopes of getting some more luscious home grown food and veggies before old man winter comes along and spoils your plans for fresh, homegrown produce.

If you would rather spend your time planting instead of doing math, the folks at Johnny's Selected Seeds were kind enough to let me share their Fall Planting Calculator with you. Just put your cursor in the the square over the When to Plant column, and plug in the date that you think the first killing frost will occur. The worksheet does the rest for you.

They've got other great calculators on their website including a seed calculator, a target harvest date calculator, a caterpillar tunnel worksheet, and more. I encourage you to check them out!


More information from the Virginia Cooperative Extension:

Fall Vegetable Gardening