Why We Harden Off Our Vegetable Plants

Why We Harden Off Our Vegetable Plants

An article by Travis Key from Lazy Dog Farm

As spring approaches, hopefully you’re in full seed starting mode and have already planted your tomatoes, peppers, and more in your greenhouse or seed starting room. As we’ve mentioned in previous blogs, giving them a low dose of AgroThrive (1 tablespoon per gallon of water) 3-4 times a week is a great way to grow beautiful transplants with a healthy root system. With the outside temperatures warming, many gardeners are excited to get these transplants in the ground. But there is one more crucial step to the seed starting process that you’ll need to consider before planting, which we’ll describe below.

What is “Hardening Off”

“Hardening off” is the process of gradually acclimating seedlings grown indoors to the outdoor environment. It involves slowly exposing them to increasing amounts of sunlight, wind, and fluctuating temperatures. While it may seem like an extra step in an already labor-intensive seed starting process, the benefits far outweigh the effort.

First and foremost, hardening off strengthens the resilience of your plants. Exposing seedlings to outdoor conditions encourages them to develop thicker stems and sturdier leaves. This physical toughness makes them better equipped to withstand the stresses of weather, pests, and disease once they're transplanted into the garden.

Hardening off also helps prevent transplant shock. Imagine being plucked from your cozy living room and thrown into cold weather without warning – it would be a shock to your system. The same goes for seedlings. By gradually introducing them to outdoor conditions, we give them time to adjust and minimize the shock of being transplanted.

But perhaps the most compelling reason to harden off your vegetable plants is to maximize their productivity. Plants that have been properly hardened off are more likely to establish strong root systems and experience faster growth once they're in the ground. This means earlier harvests and higher yields, which all gardeners can agree is a good thing!

The Hardening Off Process

So how does one go about hardening off vegetable plants? It's a straightforward process, though it requires some time and patience. Typically, it's best to start hardening off transplants about one to two weeks before you plan to transplant your seedlings into the garden. Begin by placing your seedlings outdoors in a sheltered location for a few hours each day, gradually increasing the amount of time they spend outside. Choose a spot that offers some protection from direct sunlight and wind – a shaded porch or under a tree works well. Keep a close eye on your seedlings during this time, watching for signs of stress such as wilting or yellowing leaves.

Each day try to gradually expose your seedlings to more sunlight and wind, paying attention to weather conditions. If temperatures are particularly cold or windy, it's okay to scale back the amount of time your seedlings spend outdoors. Remember, the goal is to toughen them up, not push them to their breaking point.

It’s also a good idea to scale back on your watering as you approach transplanting time. While the transplants may receive water every day in your greenhouse or seed starting room, they probably won’t get as much when planted outside. Slowly reduce the watering frequency so that the plants can adjust to less frequent watering in your backyard garden.

By the end of the hardening off period, your seedlings should be ready to face the world outside. Their stems will be thicker, their leaves stronger, and their roots will more easily establish in their new soil. When you finally transplant them into the garden, take pride in knowing that you've given them the best possible start in life.


Thousands of gardeners have been tuning in to The Lazy Dog Farm YouTube channel where Travis covers a variety topics ranging from how to successfully start seedlings to how to make a flavorful hotsauce that packs a punch. Accompanied by his wife Brooklyn and their two boys, the gardens on their 2 acre homestead in southwest Georgia are always filled with a wide variety of vegetables that are enjoyed fresh or preserved for later.

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