The season’s first frost doesn’t always wait for winter! As a matter of fact, it can happen on a night when the forecast looks perfectly harmless. Picture this: one evening, your garden is thriving. Your tomatoes are still producing, your peppers are ripening, and your favorite fall flowers are putting on their final show of the season.
Then, seemingly out of nowhere, temperatures suddenly dip overnight, and by morning, your tender plants can be blackened, wilted, and sadly, beyond saving.
Therein lies the danger: The first frost can sneak up on you.
As September turns into October, nighttime temperatures can fall dramatically even when daytime temperatures are still warm and comfortable. That’s why knowing when it will freeze — and having a way to monitor temperatures where your garden actually is — can make the difference between enjoying a few more weeks of your garden and losing it overnight.
What Temperature Causes Frost?
When most gardeners think about frost, they think of the temperature dropping to 32 °F (0 °C). While that degree mark certainly is an important number, there’s a little more to the story.
Frost can form when temperatures at or near the ground are at or below freezing, allowing moisture to form ice crystals on exposed surfaces. Frost point is defined as a temperature below 32 °F at which moisture in the air can condense as frost on exposed surfaces.
Because temperatures can vary considerably from one part of your property to another, your backyard may experience frost even when the temperature reported by a weather app or forecast from your nearest airport is slightly warmer.
Low-lying areas, open lawns, and exposed gardens can cool quickly after sunset, which is why knowing your own backyard temperature matters.
When Will It Freeze?
Listen closely every September, and you’ll hear the question every gardener starts asking in late September: “How cold is it actually going to get tonight?”
A forecast predicting temperatures in the upper 30s might not sound alarming, but if your garden is especially exposed, a few degrees in either direction can make all the difference. The forecasted low temperature isn’t necessarily the temperature every plant will experience. Your garden’s elevation, wind, humidity, and exposure — all things that make up its microclimate — can all influence conditions.
Instead of relying solely on a general forecast, consider monitoring the temperature right where your plants are growing. That gives you another layer of information when deciding whether it’s time to cover plants, move containers indoors, or harvest those last few vegetables.
If anything, remember this: when nighttime temperatures are approaching the mid-30s, start paying attention.
If your thermometer drops toward 33 °F (0.55 °C), that’s a good time to be ready to act. To give you a heads-up to dropping temperatures, an AcuRite Weather Station with a programmable weather alarm can help. Configure your weather station to sound an alert when outdoor temperatures fall below a user-selected threshold, such as 33 °F for a frost alert.
How to Protect Your Garden From the First Frost
Just because you could be surprised with an early frost doesn’t necessarily mean your growing season has to end! A little preparation can buy you some valuable time. Follow the steps below to keep your garden going into the cool fall season.
1. Cover Tender Plants
If a frost is expected, cover susceptible plants before temperatures fall. Use frost cloth, blankets, or other breathable coverings designed for plants. Avoid allowing plastic to rest directly against foliage, as it can transfer cold and potentially damage plants. Ideally, cover plants before sunset so they can retain some of the heat accumulated during the day, and don’t forget to remove coverings in the morning once temperatures rise.
2. Bring Container Plants Indoors
Potted plants are particularly vulnerable because their roots have less protection from the surrounding ground. Move tender containers into a garage, shed, greenhouse, or indoors when practical. If you’re trying to extend the life of herbs, flowers, or ornamental plants, this simple step can sometimes give you weeks of additional enjoyment.
3. Harvest What You Can
If you suspect or hear that a hard freeze is approaching, don’t wait! Harvest mature tomatoes, peppers, herbs, and other frost-sensitive vegetables before temperatures plunge. You may not be able to save everything, but bringing mature produce inside can help you get the most from your garden before the growing season ends.
4. Water Strategically
Moist soil can retain heat better than dry soil, so watering before a freeze can sometimes help protect plants. However, avoid watering foliage immediately before freezing conditions unless the plant-specific guidance calls for it. The goal is to prepare the soil, not create a layer of moisture that freezes on the plant.
5. Watch the Temperature, as well as the Forecast
This is one of the easiest steps to overlook. You can check your weather app. You can watch the evening forecast. You can listen to the local meteorologist. But what is the temperature in your backyard right now? That’s where a digital thermometer or weather station can become an incredibly useful gardening tool.
Don’t Wait for Frost to Tell You It’s Too Late
AcuRite weather stations and digital thermometers can help you keep an eye on temperatures around your home, so you can make decisions before damage occurs. Take advantage of the programmable weather alarms to get an early warning to freezes, which is a valuable advantage on a busy fall evening.
Say goodbye to always checking the thermometer. Set the alert and let the thermometer watch the temperature. When conditions reach your chosen threshold, you’ll know it’s time to head outside.
Want to Know What’s Happening While You’re Away?
For gardeners who want an additional level of monitoring, connected AcuRite systems can provide remote temperature alerts for on-the-go awareness.
With compatible Wi-Fi Weather Stations and a personal mobile device, like a cell phone, the AcuRite NOW app allows you to create custom alerts based on temperature thresholds. You can select the sensor, choose whether the temperature is above or below a specific value, and receive notifications when the condition is reached.
That means you don’t necessarily have to be standing in your kitchen watching the thermometer. You could be at work, out running errands, already in bed, or away on vacation.
Ready for Your First Frost Watch?
Set yourself up before the temperatures drop with an AcuRite Weather Station. Explore the AcuRite solutions and choose the system that helps you keep a closer eye on the conditions that matter most around your home — and in your garden.
Don’t give up on your garden just yet! It may have a few more weeks left. Let AcuRite help you know when exactly it may be time to put your gardening tools, gloves, and garden beds away for the winter season.