How To Harden Off Plants Before Transplanting
For the different type of plants to grow and mature, you eventually need to transplant them into their permanent home. You’ll need to move them out of their warm cozy environment where they grew from your own seeds to delicate seedlings and introduce them to the world.
So, it’s important that you know How To Harden Off Your Plants Before Transplanting them into the garden or garden beds.
However, moving is one of the most stressful events in a plant’s life cycle. Imagine the tender seedlings growing indoors, where the weather is climate controlled, then suddenly, they’re transferred into an outdoor environment in the full sun, wind, or light breezes, and weather conditions.
To make sure the healthy plants handle this transition well, they first need to be what we call “hardened off”.
The hardening process happens when tender plants are exposed to any amount of sunlight or full sunlight, wind, or light rain, causing them to toughen up by thickening the cuticle on the leaves so that the leaves will start to lose less water once they’re exposed to other elements and a new environment.
Once proper hardening off happens, it prevents new transplants from going into shock. Transplant shock or temperature shock occurs when the indoor seedlings die from a sudden change in the night and daytime temperatures, such as changes like low temperatures to a sunny day, especially during seasonal transplanting.
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Why Should You Harden Off Plants?
When different varieties of plants are grown from seeds indoors, they thrive in a controlled environment. The temperature is maintained, the light levels are not as strong as the sun outside, and there are very minimal disturbances like rain, a windy day, or a gentle breeze, and snow which is a huge difference than the outside world.
Since the stronger plants that were grown in an indoor environment were never exposed to harsh conditions, once you transplant them, they do not have the defenses built up within their system to fight them off.
To help the young seedlings build the resistance they need, you must know how to harden plants before planting outside. Hardening off is an easy process that will help you make your plant growth stronger and healthier, especially when you plant them into your garden outdoors.
Three Approaches To Hardening Off Plants
The length of time a seedling needs to be hardened off depends on the type of plant you’re growing and the temperature. There are three approaches when it comes to hardening off tender young plants:
Exposing The Plants To Longer Periods of Time Outdoors
One tip on how to harden plants for garden is to harden off the little plants and vegetable plants in preparation for moving by gradually exposing them to longer periods of time to the harsher outdoor conditions.
- Begin by putting the seedlings outdoors for short monitored amount of time for about 7 to 10 days before you plan to move them into the garden.
- Take the plants to a shady or sheltered spot outside the large or small greenhouse or your home. It can be under a tree or on a porch shaded from the sun. I start by leaving the plants out for an hour the first day, and I increase the time by an hour each day for 7-10 days ending with them spending an entire night outside.
- I also make sure to take them out at different points in the day each day so they can get used to different conditions. I may take them out early morning one day, and late afternoon another day and so on. Place the plants back inside the greenhouse or in your home where it is warm, like the porch or your garage, every night.
- Here’s a video explaining How To Harden Off Your Plants Before Transplanting :
- After two to three days, move the plants from the sheltered spot into the sun. Return them to the shade in the afternoon.
- If the outside temperatures starts to get warmer, keep an eye on the soil. Too much sun can dry out the soil and direct sunlight can scorch the leaves.
- In 7 to 10 days, the plants should be ready for a new transplant. When transplanting them, do it on a cloudy day and make sure that the plants are watered well.
Placing The Plants In A Cold Frame
When discussing How To Harden Plants Before Transplanting, we think about moving plants directly in the yard and great outdoors. Still, we can also use a cold frame or a warm greenhouse by placing your own plants you want to transplant during the transition period into a cold frame that can also be a way to harden plants off.
- Move the indoor plants to the cold frame at least 7 to 10 days before your intended transfer.
- Ensure that the temperature in the cold frame does not get to cooler temperatures or go below 50 degrees Fahrenheit, especially during cold winters. While these plants are in a warm, sheltered environment, make sure that you are checking the soil surface and moisture level on a daily basis, especially if the plants need water.
- Turn off the heat or open the cover of the cold frame for longer periods of time every day. Start with 3 to 4 hours then gradually increase it a couple of hours like 1 to 2 hours each day.
- Close the cover and turn the heat on at night, especially on cold nights.
- In 7 to 10 days, your young plants are ready to be transplanted. When transplanting them, do it when there are proper outdoor conditions such as on a cloudy day and make sure that the plants are watered well and their water needs are met.
Not Watering The Plants For A Period Of Time
Withholding water for a period of time can harden plants for outdoors. Allowing the seedlings to wilt has the same effect as exposing them to other elements.
- Start 2 weeks before your intended transplant date. Do not water the seedlings until they start to wilt.
- Pay close attention to the leaves and stems of the plants. Do not leave them dry and wilting for a long period of time.
- Once the plants start to wilt, water them then wait for them to wilt again.
- In 2 weeks, the seedlings are ready to be transplanted. When transplanting them, do it on a cloudy day and make sure that the plants are watered well.
Things To Keep In Mind When Hardening Off
- If you gradually expose your plants to longer periods of time in the outdoors elements and outside conditions, the moving in and out process can be easier if you will put the plants in a wheelbarrow or a wagon. Moving them into the garage and into the porch is faster and easier.
- Protect your seedlings from animals and pests like snails. Place plants on a table or somewhere where animals may not easily spot them.
- Keep an eye on direct sunlight. If the seedlings are exposed to direct sunlight, it might cause the leaves to wilt easily or worse, can sunburn the leaves. If you live in an excessively windy or in a high winds area, like I do, I generally block the strong winds as much as I can to keep the tender stems from bending to the point of breaking.
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Hardening off is an important step, especially if you’re moving from a warm place to a spot with colder conditions and cool nights.
A Few Frequently Asked Questions
Do you need to harden off plants?
Yes, if not, they could suffer and die from being exposed to elements they aren’t used to.
How long does it take to harden off tomato plants?
About 7 to 10 days, just as explained above.
How important is hardening off seedlings?
Very important. They have been grown in a controlled environment and aren’t ready for the harsh elements they will be exposed to in the outdoor garden.
By following these steps on How To Harden Off Your Plants Before Transplanting, you will be assured that you’re making the life cycle of your plants stronger, and they can grow better, even if exposed to harsher conditions.
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