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Repotting

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Potted Purple Poppy Mallow.
Photo: Jardin botanique de Montréal (Michel Tremblay)

When to repot?

In theory, it is best to repot in springtime, when the rootlets are massed along the sides of the pot. Young plants should usually be repotted more frequently than older ones, i.e. once a year and every other year for slow-growing plants.

Don't use too large a pot, because the small root ball will not be able to absorb all the water and may rot if overwatered. Move up to a pot that is 2 cm wider at the rim for plants in 15-cm wide or smaller pots, and 4 cm wider for all others

Good-quality potting soil contains a good proportion of organic matter and a certain percentage of inert matter, such as sand or perlite, to which you can add some horticultural lime if you need to adjust the acidity of the soil. The organic matter helps the soil hold water and nutrients, while the inorganic matter improves drainage. Some potting mixes contain slow-dissolving fertilizers that release their active ingredients over a period of three to four months.

How to repot?

It is best to proceed as follows:

  • Water the plant a few hours beforehand.
  • Lightly tap the pot to release the soil from the sides and then remove the plant, holding it at its base.
  • Place potting soil in the bottom of the new pot so that the top of the root ball will sit about 1 or 2 cm below the rim of the pot.
  • Add potting soil around the root ball and tamp the mixture down slightly, without compacting it. Continue adding potting soil to completely fill the space between the pot and the root ball.
  • Water thoroughly.

Some plants bloom better when they are slightly potbound. These plants should be repotted in the same container. Remove a bit of soil from the surface and around the root ball. Prune an equal amount from the stems and roots, and then add fresh potting soil.

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