How to harden off seedlings

How To Harden Off Your Seedlings Before Planting Them In The Garden

There is nothing more frustrating than having tons of seedlings ready to go in the ground only to have them wither and die because you didn’t harden them off. Are you new to gardening and don’t know how to harden off your seedlings? Worry no longer, we’re unpacking all the gardening wisdom we’ve learned over the years of growing our own organic garden to teach you how to harden off your plants, trust us it isn’t as scary as it sounds.

Pin for later!

How to harden off your seedlings before planting them in the garden #rosevinecottagegirls

This post contains affiliate links, check out our privacy policy for more information. 

What Does Hardening Plants Mean?

Hardening off your plants is simply preparing them to transition out into the garden, your seedlings have been growing for the last couple of weeks in the perfect temperature-controlled, no wind or heavy rain environment. Out in the garden, it’s a whole new world, that can cause your young tender plants to go into shock. Hardening off your plants.

Hardening Off Your Seedlings

Hardening off your seedling isn’t as hard as you might think, promise! But maybe you’re wondering if you really need to harden off your seedlings? What does it really do? And can you get by without hardening off your seeds?

Do You Have To Harden Off Your Seedlings?

Just like moving from one home to another is stressful on us, transitioning out to the garden is stressful on plants. Hardening off your plants helps to reduce that stress. Can you get away without hardening off your seedlings? Yes, we’ve done it when we are short on time and need to get stuff in the ground. But as a general rule, it’s best to harden off your plants beforehand. Growing in the warm, sheltered environment you’ve provided hasn’t allowed them to develop the strength they will need to grow outdoors.

Why It’s Important To Harden Off Your Seedlings

Why is it important to harden off your seedlings? Hardening off your seedlings is important to get your plants ready to go in the garden.

  • Hardening off your plants reduces the chance of shock on your plants.
  • Hardening off seedlings helps them to slowly adjust to being exposed to wind, full sun, and rain.
  • Hardening off your plants helps your seedlings to thrive in the garden.

What Happens If You Don’t Harden Off Plants?

Not hardening off your plants before you transplant them into the garden can:

  • cause your seedlings to burn in the full sun.
  • cooler conditions can shock your seedlings.
  • strong winds can damage your plants.

All of which will set back your seedling’s growth several weeks or even kill the plant.

When Do You Start Hardening Off Your Seedlings?

Typically you should begin hardening off seedling transplants 1-2 weeks before setting out plants in your garden.

How To Harden Off Your Seedlings

How to harden off your seedlings is a pretty straight forward process, the idea is to slowly acclimate your plants to their new environment.

Hardening Off Seedlings Step 1: Check your frost dates, some seedlings like onions could be ok hardening off while you are still getting frosts. Things like tomatoes can’t handle those extremes so you will need to make sure you wait until after your last frost date before you start hardening them off.

Hardening Off Seedlings Step 2: Take your new seedlings out to a sheltered place around mid-afternoon for 1 hour the first day, continue for a week adding another hour each day. When the time is up for the day move your seedlings back into the house or greenhouse.

Hardening Off Seedlings Step 3: After a couple of days of leaving your seedlings out during the day begin acclimating the seedlings to the nighttime temperatures by leaving them out at night a bit at a time until they are out all night.  Make sure you keep an eye on the nighttime temperatures if it gets too low you’ll need to bring them inside.

Hardening Off Seedlings Step 4: By the end of the week, they’ll be ready to be transplanted out into the garden. While you are hardening off your seedlings make sure you don’t put them in direct sunlight and shield them from the wind. Seedlings are susceptible to any extreme so make sure you ease them into the full sun. You will also want to keep them moist while you are hardening your plants off.

How To Harden Off Plants From The Greenhouse

Seedlings in your greenhouse will have to be hardened off before you transplant them out into the garden. How to harden off your seedlings from the greenhouse? Place your seedlings in a sheltered place the same way you would to harden off any other plant. You don’t have to worry as much about the sunlight, but inside the greenhouse, they’ve been sheltered from the wind.


Leave your seedlings out for an hour the first day and then add an hour each day. Slowly move your seedlings out from the shelter and expose them to more sunshine and wind. After a week they will be ready to go in the garden.

How Long Does It Take To Harden Off Plants

Everyone has a little bit different method when it comes to how to harden off your seedlings, but by the end of the week, your plants should be well adjusted and ready to transplant into the garden.

Transitioning Seedlings To The Garden

How to harden off your seedlings is really up to you, just remember to slowly introduce your plants to the outdoor conditions. If you are expecting very cold weather, now isn’t the time to start hardening off your seedlings. That’s it, in one week you’ll be ready to plant your spring garden!

Did we answer all of your questions on how to harden off seedlings? If not drop them in the comments and we will do our best to answer them!

Before you go, check these out!

About The Author

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top