Deb Babcock: Repot growing houseplants
October 9, 2011
If your indoor plants have been neglected while tending to the outdoor garden, fall recreation and other autumn activities, you might have missed the growth spurts that have taken place inside. If your indoor plants have used up all the nutrients in their soil or have outgrown the pot and become root bound, it's time to move them into a new pot.
You can tell if it is time to repot your houseplant by checking the drainage hole for roots coming through or by noting when top growth becomes spindly and leaves begin falling off.
If the plant has simply exhausted the potting soil, you may repot in the same container with fresh soil. Or in the case of quite large plants that are difficult to remove from their pot, scrape off the top layer of soil and replace with fresh material. Often, however, the roots have formed a dense ball that wraps around the inside of the pot. In that case, the plant needs a bigger container.
The new pot should be about an inch wider on all sides than the root mass and an inch or more deeper that the roots — deep enough so when you water it, the water can pool around the plant's crown before seeping into the soil around the roots. If the pot is too large, the soil will hold too much water and could rot the plant's roots.
Most gardeners agree that porous clay pots are best for houseplants because they breathe through the pores. Water evaporates from the side walls and eliminates the problem of waterlogged roots. They also are heavier than plastic pots and so are less likely to tip over, especially with tall and top-heavy plants.
However, most anything can be used for containing a houseplant as long as it provides for drainage. The exception to this rule is bulbs and water plants. Both of these can tolerate the roots in standing water, often anchored by pebbles.
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Remove the plant from its container by tapping on the bottom of the pot. This is easiest to do when the soil is moist. Loosen the roots by either gently pulling them apart with your fingers or making small vertical cuts in several places around the root ball. If your plant has hard, cord-like root masses, scratch the ball of roots with a knife until whiskers hang all around the mass. The loose, dangling roots should be clipped away in a practice called root pruning. This causes the plant to grow new roots into the fresh potting mix.
Place the plant into the new pot, gently tucking new soil all the way around the root mass. When you've filled the pot, gently thump the pot on a shock-absorbing surface, such as a folded towel, to remove air pockets.
Finally, flood the pot with water checking to see that excess water flows freely out of the drainage hole. When the soil is moist, apply a small amount of water-soluble fertilizer, following package instructions.
Deb Babcock is a master gardener through the CSU Extension Office Routt County. Call 970-879-0825 with questions.