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  • Writer's pictureLoki

Step by Step Instructions for Potting Up Seedlings

After far too much rain, I finally got the chance to do some potting up outdoors today! I've been doing it in the workshop in the basement, which is fine, but doing it outdoors is just so much better. Today I was hoping to pot up Sweet William, Black and White Dianthus, Pink Chinese Celery, Nicotiana and Rose Campion, but I only got the last two done. But with this stretch of sun in the forecast, they'll be done before the weekend! I got myself set up at the picnic table with all of my supplies, a mango milk tea boba, and I got to it.

Generally speaking, you want to pot up about 28 days after they were seeded, though sooner if they're growing like gangbusters, later if they're slow.


  • A bin with a 60/40 mix of container soil and Sea Soil, plus a healthy amount of Gaia Green All-Purpose fertilizer

  • Freshly washed 4" pots (soaked overnight in a bin of bleachy water to sanitize)

  • Labels and a Sharpie

  • A tray to catch the mess

  • A compost bucket

  • Plant babies

  • Bubble tea!

A note that I didn't buy the 4" pots, or the 6 cells, all of that throwaway plastic stuff can be found for free if you ask for them in your local Buy Nothing Group (or whatever giveaway groups you might be part of), or at your local garden centre. I live down the street from Hunter's Garden Centre, and I asked if I could go through their dumpster that was overflowing with plastic pots! Given that they were used, bleaching (you can also use peroxide) is imperative, to make sure that no disease, bugs, eggs, or fungus gets transferred to your plants.

Step one:

Gently remove your seedling from its container. My method is to put my hand loosely over all of the seedlings, and then gently flip it upside down. Then I'll push (again oh-so-gently) on the bottom of each cell to loosen them up. Another soft flip and they're ready to pull out! Put them aside while you prepare your pots.

Step two:

Fill your pots almost full of soil mix, but not packed down. You want it about this full:

A 4' plant pot filled almost to the top with soil
Almost full to the brim

Then you'll need to make a small well in the centre, but not too deep, you want lots of room for your seedling to grow roots! This is maybe up to my second knuckle, so about an inch or so.

A hand is creating a well in the soil that is inside a 4" plant pot.
Building a well for the seedling

Step three:

Gently grasp one of the seedlings at its base. I like to come in from above and use all five fingers to do this part, I don't want to uproot it from its soil. Give it a tug and it should slide right out of the container. Give it a quick once-over, how is the root development? Is there any algae or mould? If so, pick it off and throw it in the compost bucket. Are there two (or more) seedlings in that one plug? If there are two equally-sized seedlings, you can pull them apart, verrrry carefully, and give them each their own pot. Or you can stick one in your garden now and see if it thrives! I ended up planting five rose campion seedlings in our sidewalk garden today, just to see what happens. You can also just compost the extras, especially if they're tiny.

The seedling on the left is a little bit rootbound, another day or two and it might not be too happy! In that case, I'll loosen it up, pulling the soil apart a bit to spread out the roots. The one on the right is perfect, lots of root development all through the soil, right to the bottom, but not overcrowded.

Pro tip! Bottom water the tray that the containers are sitting in an hour or two before potting up. This makes sure that they'll come out of the containers more easily, it ensures that the roots are juicy and flexible, and it just makes them that much happier when they get into their new home.

Step four:

Nestle your seedling into the well in the new pot. Don't squish it in too hard, remember that you want room for further root growth! Press down on the soil around it, your seedling will likely stick out a bit above it when you're done.

Step five:

Top it up with more soil. I like to use one hand to push the seedling and all of its leaves off to one side so I can dump a big pile of new soil in to cover the original plug. I do this on one side and then the other, and then spread the new soil evenly around. Then again gently press it all down, lifting the leaves and ensuring everything is all tucked in.

Step six:

Label every pot! Enough seedlings look alike that it is very easy to forget which is which. I'm growing three varieties of nicotiana, fours kinds of tomatoes, three different echinaceas, I might die if I don't label them all, actually. I put the name of the plant and it's variety, the date it was seeded, and the date it was potted up. Make sure to use a marker that won't wash or rub away easily.

And that's it! Rinse and repeat until all of your babies are moved into their new (temporary) homes. Bring them back to where they're been living and say nice comforting things to them. They might be a bit traumatized by all the excitement! Again, I prefer to bottom water, but that's because they're in a very humid basement. If yours are in a windowsill, or otherwise fairly dry area, watering them from the top is a good idea.

Here's to more sunny days!


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