Hardening Your Seedlings

Hopefully you got your vegetable seeds started already, although you can still start them if you haven’t done so yet (see my Seed Starting blog for more information). Once your plants have sprouted and are doing well, you will probably need to move some to larger containers, and begin to harden them off. For those of you not familiar with this term you are in luck, because here is a blog that explains what it is and some tips for doing it.


sprouting plants

Seedlings about 10 days after planting

What is Hardening off?

Hardening off is just a fancy term for introducing your plants to the elements they will soon be exposed to. As teenage plants, this is their first taste of the real world before they go out and experience it on their own. Hardening off stresses the plants just enough to make them stronger, by slowly exposing them to outdoor conditions.

Transfer Large Plants

Before beginning the hardening process, make sure your plants have sufficient room to grow. Some of the fast growing large plants (pumpkin, melons, corn) have large roots that need more space. In our starter tray, we had corn roots that were growing several inches outside of the starter pods, so we knew our corn babies needed additional space (along with the pumpkins, watermelon, and squash). To transfer the seedlings, fill a small pot with some potting soil, place the plant in the new pot, and fill with additional potting soil to match the top of the pod. Some sources say to leave the roots alone to minimize transplant shock, while other sources mention teasing the roots to get them growing into the new soil. We minimally teased our roots, and so far our plants are doing really well in their new pots. (For a humorous take on this process check out Movin’ On Up by Seed to Salad)

transfer large plants

About 2 weeks after planting our seeds, some of the larger plants needed more space

Hardening Process

There are many variations out there on how to harden your plants, but the bottom line is that you do it slow and watch for signs of too much stress. There is no rush for the process, and the longer you take, the more time your seedlings will have to adjust to the harsh conditions of the outdoors.

Once your seeds have all fully germinated and sprouted, begin by placing your seedlings in a protected shady outdoor area for just an hour or so. Each day, slowly increase the time and gradually transition them to more sun. Since your seedlings are in just a small amount of soil, it is important to watch them closely so they don’t dry out. Also, since up until now your seedlings have been inside and out of direct sunlight, note that too much sun can also burn your plants.

Another thing to be very cautious of is the outside temperature. Make sure you bring your plants inside before the temperatures drop below the plants’ minimum growing temperatures or you will kill them. This is also something you need to keep in mind when planting time comes, if you plant too early and the temperatures drop, there go your plants. Here is a great reference article from the University of Nevada – Reno that goes into the specifics on hardening off seedlings, house plants, and ornamental plants.


I hope this helps you in transitioning your teenage plants to the outside world. Please feel fee to share your personal experiences in the comments section below. There are many different takes on this process and I would love to hear what you have to say.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s