The National Oceanic & Atmospheric Administration has an interactive map where you can see the time of year, on average, that areas across the nation can expect to see their temperatures dip to 32°F or below for the last time. According to the map, the estimated last day of freeze for Metro Louisville is April 1st – 15th; however, because we are in a “warm pocket” surrounded by “cooler counties” this puts us at higher risk for a drop in temperature later than estimated.

WHY IS THIS IMPORTANT?

Some plants can be damaged or even killed by frost or freeze, so it is important to use this information as a guide for scheduling your spring plantings and gardening activities. Cold-sensitive annuals, warm-season vegetables, and tropical plants, including houseplants that are taken outside, will need to be protected from the potentially damaging frost or freezes we might see in the early spring.

BUT WAIT, THAT’S NOT ALL

In addition to air temperature, the soil temperature is also an important factor in the germination, establishment, and production of many warm-season annual flowers and vegetable crops, especially tomatoes and peppers. This is why, even if we don’t have a frost or freeze in late April or early May, we still recommend waiting to plant them. While the air temperature warms up quickly the soil warms up slowly. Planting some crops too early before the soil temperature is 60 degrees Fahrenheit or higher can cause stunting and reduced production even if the air temperature is warm and the growing season is picture-perfect.

WHAT CAN YOU PLANT IN EARLY SPRING?

March and April is a great time to plant trees, shrubs, perennials, and herbs that are winter hardy in our zone. It is also a great time to plant early spring crops like pansies, lettuces, kale, collard greens, cauliflower, broccoli, brussel sprouts, cabbage, chard, carrots, radishes, peas, spinach, bok choy, mustard greens, and arugula.

Plants with high frost/freeze sensitivity include basil, tomatoes, peppers, sweet potato vine, annual vinca, impatiens, and other plants fresh from the greenhouse that have not had a chance to harden off. You should wait to plant these until late April or better yet, early to mid-May.  If you acquire any of these cold-sensitive plants or want to purchase these plants early in the season, you will need to take appropriate measures to protect them from the potentially damaging soil temperature or any frost or freezes we could see in early spring.

Have more questions? Send us an email, give us a call, or send a text because our team is experienced and ready to help. You can also click here to read the full NOAA article about the time of year, on average, that areas across the nation can expect to see their temperatures dip to 32°F or below for the last time.