The last frost date is one of the most important dates for gardeners. The last frost date determines when to plant the vegetables and ornamentals at the best possible time for maximum growth over the season. Some plants like being planted before the frost date while others have to be planted afterward.
Last year Spring and warm weather came early to Middle Tennessee where we live. My heirloom vegetable plant business targeted the last frost date then factored in two extra weeks to allow the soil time to warm up. My plan was to offer my plants at just the right time for planting to my customers. I wanted to give my customers the best possible conditions for their gardens to succeed. Normally the last frost date for our area of Middle Tennessee is April 15th and if you add two more weeks to give the soil time to warm up you end up with a planting date at the end of April. The weather last year was different. It warmed up very early and daring gardeners were able to get their warm season plants planted extremely early.
I don’t recommend planting warm season plants before April 15th. I noticed last week that one of our home improvement stores already had their warm season plants on the shelves. The morning I was there was right after a hard frost which killed a good portion of their warm season vegetables. Many gardeners don’t realize the importance of the frost date and assume that because the store provides them it must be time to plant. It definitely isn’t a good way to determine when to plant your vegetables!
Gardeners need to know when the frost date is for your area. It can vary greatly depending on where you live. The farther north you live the later the frost date will be but other factors can effect your frost chances on a local level. If you live on a shaded hillside or in a frost pocket your safe planting date may be later too. Sometimes factors like stonework, paving, and brick walls can create heat sinks that will effectively move the frost date up a little.
If you want to cheat the frost date even more consider using old windows to create mini-greenhouses or use milk jugs for cloches (See my post Seed Sowing 101: Timing Your Seeds is Everything for more info). To heat the soil up faster lay clear plastic over the area for a couple weeks before planting.
Remember the last frost date is just a guideline for determining when to plant and is not a guarantee It’s possible frost could happen after the last frost date but the odds are much lower after that date. Just watch the weather and watch the calendar. Those are two things gardeners excel at!