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The Art Of Potting Up Seedlings – A Complete Guide

by on April 21, 2024
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Potting up seedlings is one of those gardening tasks that often leads to many questions and concerns. “When is it time to pot up my seedlings? How many times do I have to pot them up while indoors? Do I actually have to pot them up? What will happen if I don’t?” And so on and so on…But I get it, the task of potting up can be confusing! So hopefully this post covering what, when, why and how you should pot up seedlings will help! Plus, I’m sharing my personal approach and philosophy on the matter…which kinda differs from what the majority of the internet tends to suggest!

What Is “Potting Up” Seedlings?

Simply put, the easiest way to define “potting up” seedlings is the task of increasing the size of container they’re living in.

“Potting” refers to the pot/container/seedling tray you’re using. And “up” refers to increasing the size of it.

The way I envision potting up is giving my seedlings a new, larger home before they go into their final growing space outside.

Why Should You Pot Up Your Seedlings?

Every Spring, I pot up thousands of seedlings for our garden & greenhouse. And to be completely transparent, I don’t really enjoy the task of potting up…and often put it off until my plants are way too big for their existing containers.

But when I DO prioritize potting up my seedlings, it hugely pays off in more ways than one.

Here’s how and why you too should pot up your seedlings.

Firstly, you should pot up your seedlings because it will lead to healthier, happier plants in the long run.

Potting up allows your seedlings further room to develop and grow their roots, which in turn will lead to stronger and bigger plants once transplanted outside in your garden.

Secondly, you should pot up your seedlings because it can drastically reduce their chance of developing disease.

When seedlings sit in the same soil and small container for long-term (especially inside where there isn’t a ton of air flow), the chances of seedlings contracting an air born and/or soil born illness increase.

You may even be experiencing some seedling issues as you read this post. If that’s the case, potting up could certainly be one way to solve the problem. But before you do so, be sure to check out my post 5 Common Seed Starting Problems & How To Easily Fix Them so you know for sure the best course of action!

And lastly, a final reason for potting up your seedlings is that it provides them with new soil with more nutrients and food — both of which I’ll cover in more detail further down in this blog.

When Do You Know It’s Time To Pot Up Seedlings?

This is hands down the most asked question I get when it comes to potting up seedlings. How do I know when it’s time to pot up my seedlings?

Well, there’s a few different philosophies floating around the internet on this topic…

Some gardeners believe in potting up their indoor seedlings to larger containers two to three times before they transplant in the garden. Whereas other gardeners don’t pot up their seedlings at all before transplanting, believing that it’s better not to disturb the root systems at all.

So who to believe and which approach to follow?

Well, let me share with you my philosophy on potting up seedlings and you can decide for yourself.

The From Soil To Soul Approach To Potting Up Seedlings

I personally believe that seedlings don’t necessarily need to be potted up and there’s several factors that will indicate how you know whether to pot up or not.

Here’s how I approach potting up seedlings with my own seed starting:

I group my seedlings into two categories.

Category 1 = any seedlings I’ve started indoors in December, January and February.

Category 2 = any seedlings I’ve started indoors from March onwards.

For category 1, I know these seedlings will inevitably need to be potted up at least once because they will be spending 4-6 months living inside my home and will definitely become too big for the original cell in their seed starting tray that they started in.

For category 2, I determine whether or not to pot up my seedlings based on these three tricks.

3 Tricks For Knowing When To Pot Up Seedlings

Each trick applies to different types of plants, so be sure to use accordingly based on what you’re growing.

Trick 1: Can you see the soil below the seedlings leaves when looking from directly above? If no, it’s time to pot up. If yes, there’s still room for the plant to grow.

This first trick works especially well for fruiting vegetables like peppers, tomatoes & eggplant, which is what’s pictured above.

There’s not much more to elaborate on here, folks! It’s pretty self explanatory.

If you can’t see the soil surface when looking from above, then your plant likely needs to size up its home.

Trick 2: Are the roots growing out the bottom of the container? If yes, it’s time to pot up. If no, the seedling still has room to grow.

Gently turn your container upside down, being careful that the seedling does not fall out, and/or gently lift it from its container to see how the root development is coming along.

There’s two things to look for here that will indicate whether potting up is in fact necessary.

The first is to look for long roots that hang out the bottom of your containers holes, as pictured above. This is a clear indication that your seedling’s roots need more room and soil to grow in.

The second thing to look for are roots that are tightly woven together when you lift the seedling from its original container. This is called “root bound” and refers to when roots have formed into a dense, tangled mess. This is another clear indication your seedling needs a bigger home.

This trick is best applied to flowers, woody herbs and vegetables in the cucurbit family, such as cucumbers and squash.

Trick 3: Have I seeded multiple plants together in one cell and/or container? If yes and they have their second set of leaves, it’s time to pot up.

Community sowing or cluster sowing, as some people call it, is the practice of planting multiple seeds inside one container and then separating them as they mature.

I like using this approach when seed starting herbs (like the above pictured basil), veggies and flowers, such as eucalyptus.

I will also community sow when starting really small, fine seeds, like I’ve demonstrated here on my Instagram reel!

The downside to this approach is that you 100% have to pot up seedlings that are sown together as they will more quickly require additional growing space and their own container.

How To Easily Pot Up Seedlings

Please don’t overcomplicate potting up! It doesn’t have to be confusing at all. In fact, it’s really easy.

So how do you post up seedlings? And what’s the easiest way to pot up seedlings?

5 Easy Steps For Potting Up Seedlings

I always find it’s easier to follow a process when it’s broken down into easy-to-follow steps. So that’s exactly what I’ve done for you here!

Step 1: Select the correct container size.

My rule of thumb is that seedlings should move into a container that is no bigger than two to three times the size of the home they are coming from.

For example, if your seedling was in a 2inch deep cell, as picture above, they should move into a container that is between 4-6inches deep.

Now I know what you’re wondering next….“Can you hurt your seedlings if they go in a container that’s too big?” I’ve often wondered the same!

You can’t necessarily “hurt” them but you may find they have a hard time establishing themselves in a space that is too large. Plus, you will be wasting soil if you’re putting a tiny seedling into a massive container. It simply doesn’t need that much soil or nutrients just yet.

So as mentioned, it’s best to size up to a container that’s no more than 2-3x the size of the original.

What Are The Best Containers To Use For Potting Up Seedlings

My personal favourite containers to use for potting up seedlings are biodegradable pots made from either cardboard, peat moss or coco coir as pictured here.

I love these options for a few reasons!

The first being that they will break down in your compost pile at the end of the season, so no waste! Plus, they eliminate the need to buy and store plastic containers during the off season, which is so nice!

Secondly, I love these containers for potting up because if you have a plant that has especially sensitive roots you can plant the entire container in the soil, allowing you to transplant without disturbing your seedlings roots. The container will gradually break down throughout the growing season. Although I have found it takes quite a long time to do so.

And finally, the more durable compostable containers, like the coco coir ones, will actually hold up for multiple seasons so you can save them and replant seedlings in them again for at least 2-3 years.

Step 2: Build your soil blend.

If you’ve read my other posts, then you know how important I believe healthy soil is for the development of strong, healthy plants. So don’t skip out on building a healthy soil blend for potting up.

By the time your seedlings are ready to be potted up, they will be strong enough that they can withstand a heavier soil blend and one with some additional nutrients in it.

What Soil To Use For Potting Up Seedlings

My personal soil blend when potting up seedlings is as follows:

  • 1 part compost — anything works but I suggest using a compost that is fine and doesn’t have any large chunks in it
  • 2 parts potting soil — I use either ProMix or Sunshine Mix #4
  • 1/4 part worm castings — I love Mind & Soil, my code FROMSOILTOSOUL will get you free shipping on orders over $75

Mix your soils in a large container (I like to use this large kitchen mixing bowls as pictured above).

Then, gradually add in water until your soil is wet enough that is holds its form when you squeeze it in your hand. You don’t want it to be dripping wet though.

So add additional soil/water as needed until you get that perfect consistency.

Step 3: Gently remove your seedling from its original home.

This step is key to have potting up success! Seedlings are baby plants and should be handled with care.

The best and easiest way I’ve found to gently remove seedlings from their original planting cell, is by using a steel hairpin, as pictured here.

You can likely purchase these at your local hardware store. The other way I use these hairpins is to hold down my shade cloth, row cover and drip irrigation. So they serve more than one purpose!

To remove your seedling from its cell, gently push down the hairpin into the outer edge of the soil, pinch it together so it has a secure hold on the plant, and then remove it.

Alternatively, you could use your fingers to remove your seedling from its cell. If doing so, try pushing up on the bottom of the cell so the bottom roots of your seedling loosen more easily.

Step 4: Replant your seedling being cautious of its growing habits.

When replanting your seedling into its new home, be sure to familiarize yourself with the plant’s unique growing requirements.

For example, some seedlings do not like having their roots disturbed at all, whereas others will do better if you gently massage and break up their root systems.

Further to that, some seedlings do better when their stem is buried deeper in the soil, whereas others do not.

So how do you know how to properly pot-up different varieties of seedlings?

Well for starters, the longer you garden the easier it becomes and you start to just pick these things, remembering year after year each plant’s preferences. So if you’re a beginner gardener, don’t stress – it will get easier!

If you do need things simplified a bit, follow my potting up cheat sheet!

Easy cheat sheet for how to pot-up specific seedlings:

Screenshot this list or bookmark the page for future reference as you’re potting up.

For Plants In The Nightshade Family (tomatoes, peppers, eggplants)

Gently massage roots to break up slightly, then bury the majority of the stem under soil so just the top leaves are peeking above the soil’s surface.

For Plants In The Brassica Family (kale, broccoli, cabbage, cauliflower, etc..)

Bury more than half of the stem under the soil if the stem is sturdy, bury less than half of the stem under the soil is the stem is leggy. Leave roots in tact unless root bound.

For Flowers & Herbs & All Other Veggies

Don’t bury the stem at all and instead delicately plant the roots into new soil being careful not to disturb them

And there you have it!

3 Top Tips For Potting Up Seedlings

1. Fill your container 1/4 of the way with soil and then use your fingers to make a small hole in the middle for your seedling to fit into.

2. Use your middle and pointer finger to pack soil around the rest of the plant, being delicate as you do so.

3. Be sure the plant is securely in the middle of the container. Don’t be afraid to apply pressure with your fingers, patting the soil all around until it’s tightly packed in place.

Step 5: Water.

Last but certainly not least, be sure to water your seedlings after they’ve been transplanted into their new home.

If you’ve carefully followed my 5 steps to potting up seedlings, then your soil should already be moist when you put them in their new container. But watering them once more is beneficial too.

Why Should You Water Seedlings After Potting Up?

After potting up, your seedlings will be a little stressed out. Watering them is a good way to alleviate some of that stress and help them feel comfortable.

For smaller seedlings, use a turkey baster, spray bottle or other tool that will release small amounts of water at a time so you don’t water log and/or drown your baby plants.

For larger seedlings, you can try bottom watering them — a method I love and explain in full detail here in this post.

Should You Fertilize Your Seedlings After Potting Them Up?

There’s no hard and fast rules that say you should or shouldn’t fertilize your seedlings after potting them up.

But my personal philosophy is to not fertilize seedlings after potting up. There’s a few reasons for this.

The first being that your soil blend will already contain an abundance of nutrients and fertilizer from the compost and worm castings. So fertilizing right after potting up won’t hurt your plants but it might not have any real benefit. Think of it as basically giving them more than they need.

Secondly, because your seedlings will already be a little stressed out from their transition to a new living environment, it’s best to take a “less is more” approach. Let them settle in for the first week or so before fertilizing or doing anything else.

What Should You Do After Your Pot Up Your Seedlings?

The most important things to do after you pot up your seedlings are as follows:

First be sure to continue providing them adequate direct light for 10-12 hours/day. If you’re in a Northern climate like me, this should be from grow lights. However, if you’re potting up later on in the gardening season, outdoor daylight may be sufficient. Further to that, daily light from a greenhouse is great too!

Next, be consistent with watering and fertilizing. Wait 1-3 weeks after potting up your seedlings to fertilize them. I cover both fertilizing and bottom watering seedlings in great detail here in this post.

And finally, be sure your newly potted up seedlings are getting lots of air circulation while indoors. A clip-on fan is a great way to do this!

What To Do If Your Seedlings Look “Bad” After Potting Up

You may find your newly potted up seedlings look a little wilted, sad or stressed out.

This is normal! And also pretty common if you are potting up seedlings outside in direct sun and/or heat.

So if your seedlings are looking “bad” after potting up, simply take them out of direct sunlight (if outside, if under grow lights let them be), provide some airflow from a fan or fresh air and let them be for 24-48 hours.

You will likely find your seedlings perk up after they’ve adjusted to their new home. Just have patience.

And there you have it folks! That’s your complete guide to the art of potting up seedlings.

I hope this blog post included everything you need to know, plus the what, when, where and why of potting up!

If there’s something I missed or a question you need answered, don’t hesitate to leave a comment. I LOVE hearing from you and answer all comments.

For more potting up content and general gardening goodness, join me over on Instagram, Tik Tok & Pinterest.

Happy gardening!

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Latest Comments

  1. May 5, 2024

    Thank you for this most informative article. I started reading and as I went along the information continued to fit my gardening needs. I appreciate this so much. Many articles I read, while being informative to others in different growing zones, do not fit my situation. As I read along till the end I was delighted to find you too are a prairie girl. Thank you.

    — Helen Mansuy
  2. May 21, 2024

    Thanks for the comment, Helen! Happy you’ve found your way here 🙂

    — Maggie