Question: The roots of my spider plant are pushing the plant out of the pot. Should I repot it or divide it into two smaller plants? I also notice roots on the hanging spider plantlets. Will those grow if I cut them off and pot them in soil?
Answer: It is time to divide or repot spider plants (Chlorophytum) when the roots push the plant out of the pot. You could either move the plant up one or even two pot sizes or you could also cut the plant into two or more pieces with a sharp knife and plant each piece into its own pot. The “spider plantlets” which are starting to form roots will also grow readily if potted into soil. You could either plant individual plantlets into small pots or place several plantlets into a larger pot.
Other indoor plants also outgrow their pots and should be shifted into a larger pot, or else divided into two or more smaller plants. Most indoor plants do not push themselves out of the pot like spider plants. However, you can tell if they need repotting by tipping them upside down and gently tapping the edge of the pot until the plant slides out. If you find a thick layer of roots all the way around the soil ball, they are probably ready to repot.
When repotting plants with a thick layer of roots, the roots should be pulled loose along the sides and bottom. Pull the bottom roots so they point downward. Trim off excessively long roots so they will fit into the new larger pot without being bent sideways.
Check the potting soil to see if fertilizer has been added to it. If it has fertilizer you will not need to add any until the plant has become re-established for a few weeks. If there is no fertilizer indicated in the potting mix you could mix some coated slow release or timed release fertilizer with the soil before repotting. This will place fertilizer near where the new root growth will occur. Liquid fertilizer could be added instead.
Pots should have a half inch of room above the soil after watering the first time after repotting. This will leave adequate room for watering.
Plants can be divided even if they do not have a layer of roots around the soil ball. Plants with several growing points arising from the soil are the best for division. If you divide a plant you will usually place each division into a smaller pot than it was growing in originally. You want to have room for new roots to grow, but not so much room that the soil stays wet continually. The exception to this would be rapidly growing plants like spider plant. You could divide one in half and place the half plant back into the original container.
When shopping for indoor plants, I like to look for plants which are already large enough for repotting. I can sometimes find a 4 inch plant for half the price of a 6 inch plant and immediately shift it into a 6 inch pot.
Allen Wilson can be contacted at firstname.lastname@example.org.