Repotting Large Containers

Occasionally, Japanese maples, roses, bamboo (especially bamboo) and other large container plants need to be re-potted. How can you tell if it’s time? If you feel a particular plant didn’t do so well last year, or that water ran right through the pot without being absorbed, then probably its time to repot. Repotting doesn’t always mean going to a bigger pot. It could just be a case of trimming the roots and replanting into the same pot using fresh soil.

Handling big pots is easier than it looks if you know a few tricks and have someone to help. A day or two ahead, check the moisture in the containers. It’s easiest to repot if the soil is damp right through, but not soggy.

Before you start, you will need some fresh soil. The easiest to use is premixed potting soil — avoid light weight peat-based mixes. Alternatively, you can use a bagged soil mixed 50/50 with bark. If you prefer to mix your own soil — the ideal blend is equal parts finished compost, bark mulch and garden soil.

Its best to use sterilized soil for Japanese maples, as garden soil can harbour harmful fungal spores.

Time to get started. Make clean-up easy by spreading a tarp to work on. Run a long, sharp knife like a bread knife, around the sides of the pot. When it seems loosened, lay the pot on its side and carefully pull the plant out. This is easiest if the container has straight sides, but will take much more effort if the sides are curved inwards — a good thing to remember if you are buying new pots. You don’t have to be too gentle at this stage, especially if the plant is dormant. Plants are tougher than you think.

Tease the soil away from the roots with a small hand fork and trim long circling roots. If the root mass is solid, use an old knife, pruning saw to cut away a couple of inches from the sides and bottom.

Clean out the container and check that the drainage holes aren’t plugged. Cover them with screening to keep them open. Mesh dry wall tape or old window screen work well.

Add fresh soil mix to the pot and reposition the plant so that the top of the root ball is at the same level it was before you started. Fill in with the soil mix to about two inches from the top. Tamp the soil down gently around the roots so there are no air pockets. Then return the pot to its permanent position. Top dress with a slow release fertilizer and water well. Lastly, prune for shape and remove any damaged or inward growing branches.

If your containers are too big to move, scrape away what you can off the old soil and top up with some fresh soil mix instead.

Find more garden solutions at Russell Nursery, 1370 Wain Rd. in N. Saanich russellnursery.com