Vigorously growing indoor plants need repotting every year or two, in early spring just before a new flush of growth starts. Mature plants making little new growth each year are repotted when necessary: this may be in 3 years or in 10.
With regular fertilization and thorough watering practices, the house plant’s roots need little soil to support top growth. Some signs which could indicate that your plant needs repotting are:
1 = decreasing leaf size on new growth
2 = roots appear on soil surface
3 = plant wilts rapidly after watering, and soil dries out quickly
4 = lower leaves turn yellow
Check this by knocking the inverted plant out of its pot: a solid mass of roots with little or no soil showing confirms that repotting is necessary. The new pot should be about 2″ wider and deeper than the old one. Underpotting is preferable to overpotting where most foliage plants are concerned.
To assist drainage, particularly in larger containers, use a layer of broken pot fragments or pebbles at the bottom of the pot.
A good general house plant soil mix consists of one part sterilized soil, one part peat moss, and one part coarse sand. This can be varied to come closer to the texture and content of the soil your plant has been thriving in: most Philodendron, for example, are grown in peat moss alone. Whatever the moisture, it should allow water to drain through while retaining sufficient moisture that you don’t have to re-water in a few hours.
WHAT SHALL I DO WITH MY FOLIAGE PLANTS WHEN I GO AWAY?
Foliage house plants can be left untended for several days and even weeks, with a few minor preparations.
Reduce Light – Move plants away from direct sun and strong light.
Lower Temperature – is usually no problem in winter since the thermostat is turned down: in summer move plants to a shaded room or one with north facing windows.
Reduce Water Loss – by increasing the relative humidity around the pants: group them together as in winter: wrap a plastic bag around each pot to prevent water losses from the soil and through the container: very small plants and cuttings can be placed inside a large plastic bag with supports to hold the plastic away from the leaves-leaving one end open to prevent excessive condensation.
Plants In Bathtub – when you leave for two weeks or more, your bathtub may be the ideal place for your foliage plants. Run in cold or tepid water to a depth of 1 1/2 to 3″: stand larger pots in the deep end, smaller ones where water is shallower: crowd them together as much as you like without breaking them. A watertight tub makes an excellent keeper for plants, though they may be pale and have stretched new growth to be pruned out when you return after a prolonged absence. Smaller scale keepers use the sink a basin, or other containers.