How to harden off tomato plants

Slow move to the sun

Slowly expose tomato transplants to increasing amounts of sun. Let all plants started indoors make this gradual transition.
Slowly expose tomato transplants to increasing amounts of sun. Let all plants started indoors make this gradual transition. | Source

Tomato flowers

If you buy a tomato plant that is already blooming, pinch off the flowers. Allow your plants to develop a strong root system before producing fruit.
If you buy a tomato plant that is already blooming, pinch off the flowers. Allow your plants to develop a strong root system before producing fruit. | Source

Growing strong tomato plants

“Hardening off” is acclimating your indoor grown seedlings to normal outdoor growing conditions. In anticipation to transplanting tomatoes in the garden, you will first need to expose them to sunlight and outdoor life gradually.

This is also a good practice if you are moving houseplants outside for the summer. While managing unruly and heavy houseplants can be daunting, tomato transplants are simple.

No matter how bright your grow lights are, natural light will shock or even burn transplants. Heavy rain, wind, bright sunlight can kill or at least shock young transplants.

Whether you plant hybrids or heirlooms, getting plants off to a good start is the best thing you can do to enourage growth and fruit production.For more ideas to reduce transplant shock, consider using compostable or organic containers.

Why harden off tomato plants

Hardening off tomato plants lessens transplant shock, allowing pants to quickly establish in their permanent location. This practice can also keep tender plants from sunburn.

Before fruiting

Prepare your plant for heavy harvests by staking, pruning and regularly watering the plant.
Prepare your plant for heavy harvests by staking, pruning and regularly watering the plant. | Source

Making the move

Before moving your plants outside – During the indoor growing period gently brush the tops of tomato plants. Lightly waving your hand across the top of the plants will encourage sturdy stems and help them survive harsh winds.

3 or 4 weeks before moving your plants outside, transplant them into individual containers.

Making the move – Plan your garden space, leaving 3 feet between tomato plants. The more common advice is to space 2 feet apart. For determinate or hybrids like Celebrity, that is OK. I grow big indeterminate heirloom tomato plants. These plants usually grow big and just keep on growing all season. Give them more space and I believe you will get more fruit and less disease.

Locate tomato stakes or cages. Install stakes now before or at the time when you plant the tomatoes.

Transplanting - Trim off the lower leaves and branches, leaving only the top growth. If you have leggy or tall tomato plants, just dig the hole deeper. Plant the tomato deep enough to cover all but the top three or four inches of the plant.

This will give give your plant an opportunity to a strong root system able to reach deeper for moisture during the hottest part of the summer and grow a sturdy stem system.

Tomato questions

These hubs may answer you tomato questions.

  • Plant tomatoes the right way

Ask tomato planting and growing questions anytime on my Hub page: http://patsybell.hubpages.com

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Comments 12 comments

Annie Miller profile image

Annie Miller 3 years ago from Wichita Falls, Texas

We can always use ideas to help us with our tomatoes ... thank you Patsy!


Patsybell profile image

Patsybell 3 years ago from zone 6a, SEMO Author

I could quote University Extension research that supports our opinion. I have another suggestion. You've tried your husbands way; now this year try it your way. Keep me posted. Thank you for your kind words.


Patsybell profile image

Patsybell 3 years ago from zone 6a, SEMO Author

You must have been very popular with the neighbors! I would love to see your garden. Thank you for your kind words.


Natashalh profile image

Natashalh 3 years ago from Hawaii

Great tomato advice! One year we had a large garden and somehow ended up with about 120 tomato plants. It was...interesting!


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States

This is good advice, Patsybell. My husband & I always go back & forth about when to plant tomatoes outside. Putting them out too early (& without hardening them off) is so counterproductive, resulting in small toms and less fruit. Will you talk to him please? LOL. Voted up & shared.


Patsybell profile image

Patsybell 3 years ago from zone 6a, SEMO Author

I'm a few weeks away from starting tomatoes. My Texas friends who are started already. Enjoy.


KA Pederson profile image

KA Pederson 3 years ago from Texas

about to start my indoor seedlings! Good tip to try on start brushing them by hand, hadn't ever heard of that.


Patsybell profile image

Patsybell 3 years ago from zone 6a, SEMO Author

You are my new best friend. Thank you. I appreciate you.


sleepylog profile image

sleepylog 3 years ago from Australia

Great article. I'd never thought about acclimating them before, but I'll try it next year.

I've linked to this hub too and voted up and Tweeted it .


homesteadpatch profile image

homesteadpatch 4 years ago from Michigan

Very useful information.


The Dirt Farmer profile image

The Dirt Farmer 4 years ago from United States

Awesome hub! Voted up & useful. (:


MobyWho profile image

MobyWho 4 years ago from Burlington VT

"Lightly waving your hand across the top of the plants" - Makes sense; thanks. This and your other tips make me eager to get busy.

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    Patsybell profile image

    Patsy Bell Hobson (Patsybell)214 Followers
    113 Articles

    I inherited my love of gardening from mother and grandmother. I am a garden blogger, freelance writer, Master Gardener emeritus.



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