Starting seeds indoors is a great way to get an early jump on gardening and save money, but what should you do once those plants are ready to go outside? Before you know it they’ll be tall, leafy, and ready for transplanting.
You just move them to the garden, right? Well, it’s not quite that simple. But before we go too much further, you may want to know some other gardening tips as well: A Guide to Caring for Indoor Seedlings, Letting Chickens Till Our Garden, How to Save Tomato Seeds for Next Year, How and Why to Prune Tomato Plants, My Gardening Schedule, and much more!
Anyway, here’s what to do instead…you should put your seedlings through a process called ‘hardening off’.
Hardening-off is a critical stage in the life of indoor seedlings. Without it they may experience some form of shock when transplanted to the garden…an environment they’ve never weathered before. So just how does one harden-off seedlings? Everything you need to know about this process is right here! I’ll tell you why hardening off is so important, when to start it, tips I’ve learned along the way, as well as a complete schedule to follow along with! Now let’s get those baby plants ready for the great outdoors!
Why Should I Harden Off My Seedlings?
Plants that are grown in an indoor environment have never experienced the outdoor elements: rain, cold, wind, moisture loss, and full sun exposure.
It’s a bit of a shock to remove a plant from the only environment it’s ever known and place it in a completely new one! Indoor seedlings do not have the proper defenses built up for the outdoors.
Hardening off will help your seedings gradually build up a resistance so that they are better able to withstand the elements. It is a simple process that will enable your plants to grow better and stronger when you transfer them to the garden.
One of the biggest mistakes a gardener can make is taking her plants directly from the indoors to the garden without any hardening off. Plants will go into shock and quickly die without this process.
When to Start Hardening Off
This will depend on two factors:
- The size of your plants. They should be large and strong enough to plant outside. We don’t want to transplant tiny, weak seedlings into the garden!
- The temperatures in your area. When is your last frost date? You can determine yours here. You want to start this process one or two weeks before your last frost date.
Tips For Hardening Off Seedlings
- The first thing to do is to pick a shady, sheltered spot to begin hardening off your seedlings. We don’t want to leave them in direct sunlight or in an open space where they can be whipped by the wind and elements. I have a shady spot right next to the house that I use for hardening off. This will give the plants a bit of wind exposure while also keeping them out of the wide open.
- Gradually reduce the amount of waterings a week before you start hardening them off. Don’t allow the plants to wilt, but preparing them for less frequent waterings is part of hardening off.
- Bring the plants inside if the temperatures dip drastically during the hardening off period.
- It is especially important to watch the nighttime temperatures. You do not want to leave your plant babies out if the temperature dips below freezing.
Hardening Off Schedule (Print It Off Here!)
Begin at one to two weeks before you plan to transfer the seedlings into the garden.
| Day | Hours Outside | Amount of Sunshine |
| 1 | 1-2 hours | Shaded location |
| 2 | 2-3 hours | Partly shaded location |
| 3 | 3-4 hours | Partly shaded to little sunshine |
| 4 | 4-5 hours | 45 minutes |
| 5 | 5-6 hours | 1-2 hours |
| 6 | 6-7 hours | 2-3 hours |
| 7 | 7-8 hours | 3-5 hours |
| 8 | 8-9 hours | 4-6 hours |
| 9 | 9-10 hours | 6-8 hours |
| 10 | 10-11 hours | 8-10 hours |
| 11 | 11-12 hours | 10-12 hours |
| 12 | 24 hours | Full sunshine |
| 13 | 24 hours | Full sunshine |
| 14 | 24 hours | Time to plant! |
This is the two week version of hardening off. You can reduce it to one week by simply doubling the amount of time they are outside each day. Be sure to watch them and make sure the environmental shift is not too much for them!
Happy gardening, friend!
Other Gardening Tips
- A Guide to Caring For Indoor Seed Seedlings
- The Basics to Starting Seeds Indoors
- Our Garden Plans
- What to do With Roma Tomatoes
- 5 Tips for Transplanting Seedlings to the Garden
- How to Can Tomato Sauce