Did you know taking time to harden off your tomato plants before transplanting them outside can make a huge difference between healthy plants that thrive in the elements – or ones that struggle to even survive?
It’s true that the simple task of hardening off tomato plants can greatly affect how plants adapt to their outside growing conditions. In addition, it can also alter how the plants grow and produce later on in their lifecycle.
“Hardening off” is the simple process of allowing your transplants to slowly get used to the outdoor elements and conditions before being planted in their permanent location. It’s a vital step, but one that can often leave gardeners confused and overwhelmed by just what to do to prepare their plants properly for the outside world.
The good news is that the hardening off process doesn’t have to be confusing or difficult. Nor does it have to take up a lot of your time to do. But one thing is for sure, it can literally be the difference between life and death for your tomato plants.
So if you want to give your tomatoes the best chance of surviving all that mother nature can throw at them, following today’s hardening off tips and tricks will set the stage to get your tomatoes ready to handle life outdoors
Why Hardening Off Tomato Plants Is Important
Whether your tomato plants were started from seed in your own home, or you purchased tomato transplants from the local garden center, tomato transplants need to go through the process of hardening off.
The first few weeks of a tomato plant’s life start out pretty easy. Most young seedlings are rather pampered early on. Not only do they have everything they need in the way of light, water and nutrients, but they also don’t have to deal with fluctuating weather.
When you start seeds inside, the growing conditions are pretty much static. The seedlings have loose, well-draining soil, consistent lighting, frequent watering, and steady temperatures at all hours of the day. See our article: The Best Way To Start Tomato Seeds Indoors
It’s pretty much the complete opposite of what conditions are like outside. Especially in the springtime. Between wind and rain, clouds moving in and out, fluctuating temperatures, and everything else spring can throw at plants, the contrast between growing inside and outside are polar opposites.
Moving young seedlings from the comforts of indoor growing and immediately planting them outside in the elements can cause a huge shock to the plants. If the tomatoes aren’t strong enough to handle those conditions, it can severely injure or even kill the tender plants.
This is why hardening off is so important. It allows the tomato plants to slowly acclimate to the outside conditions and fluctuations for a couple of weeks before planting. This way, when you are ready for planting, the tomatoes are ready to go and as strong as they can be!
How To Harden Off Tomato Plants Outside
The key to hardening off tomato plants successfully is to start slowly. You want to gradually get your transplants accustomed to the elements.
It’s best to start the process about two weeks before you hope to plant outside. As long as the daytime temperatures are around 55º Fahrenheit or above, tomato plants can handle being outside.
This two-week time frame gives plants plenty of time to start adapting and adjusting to everything from whipping wind and harsh sunlight to the changes in temperature between day and night.
Keep in mind that you will need to water any tomato transplants left outside more often than those inside. The small amount of soil they are growing in will dry out a lot quicker in the sunlight. Be sure to check moisture levels once or twice a day to water if necessary.
Week 1 – How To Harden Off Tomato Plants
Starting about two weeks out, take your indoor started young tomato plants and set them outside in a protected area. Keep them in a location that is out of any type of harsh winds as well as direct sunlight.
Perfect places include covered porches, patios, or decks. Right inside an open garage door also works well. The plants should be able to get indirect sunlight and maybe a light breeze here and there.
The most important part about these first few days is to protect the tender plants from any type of strong wind. Winds can easily snap young seedlings in half or injure new foliage, possibly killing plants in the process. If needed, place seedlings in a box or container to help protect them from strong drafts.
Only keep the tomato seedlings outside for a few hours on the first day. In the following days, gradually increase that time frame. By the end of the first week, your plants can start to receive a few hours of direct sunlight each day.
Each night, bring the seedlings back inside to the protection of the indoors. Also, bring plants inside if there is any threat of harsh winds, rain, or large fluctuations in temperature during the day.
Week 2 & Beyond – How To Harden Off Tomato Plants
After about the first week, you can start to move the tomato plants to less protected areas. Again, work gradually so as to not stress the young plants.
When the nighttime temperatures stay above 45º, you can start to leave your tomato transplants outside around the clock. Still bring them inside if harsh winds or heavy rainfall are in the forecast.
Once you are only a few days out from planting, leave plants outside no matter the weather conditions, unless a frost is in the forecast. However, still make sure that the plants don’t get blown over or knocked down. Use a wooden box or something similar to help keep plants upright and supported.
If possible, move the tomato transplants to the exact spot where you will be planting them. This ensures that your plants will have a smooth transmission when going from their containers to the soil.
Hardening Off Purchased Tomato Plants
You also need to harden off tomato plants that you purchase from garden centers. However, the process is usually a bit quicker since these plants are usually a bit larger than homegrown tomato plants.
If you purchase plants that have already been growing outside, then you can skip hardening off altogether. But those grown in greenhouses will benefit from this process just as much as the plants you start indoors.
Give purchased tomato plants about a week to harden off. Move plants to a protected outside space but bring them in the first few days. As long as the weather allows, keep them outside all day and night before planting in their permanent location.
Once planting day arrives, your tomato plants will be ready for a healthy and productive growing season!
I Grow Tomatoes
Follow Our Facebook Page For Even More Great Tomato Growing Tips! I Grow Tomatoes Facebook Page
I Grow Tomatoes is a website created for those who love all things about tomatoes – from planting and growing – to cooking and canning! We publish two articles every week, 52 weeks a year. Sign up today to follow via email! This article may contain affiliate links.