Homeowners often become concerned about their houseplants this time of
year because they look unthrifty and may even shed leaves. Most of this
is the plant responding to low light levels. Not only is the day length
shorter, but the angle of the sun means sunlight must travel through
more atmosphere before it reaches us in the northern latitudes. Each of
these factors means less light energy reaches our houseplants.
Houseplants respond to this stress by stopping growth and dropping
leaves if necessary. So how can we tell if leaves are being dropped due
to stress or due to other factors? Normally, stress is the culprit if
leaves are dropped throughout the plant so general thinning occurs.
The next question is what do we do about it? Well, you can add
supplemental lighting or just wait until longer days and higher light
levels allow the plants to recover. Unfortunately, people often decide
the plant needs more fertilizer or water to perk it up. Remember the
problem is low light, not a lack of fertilizer or water. Adding extra
fertilizer or water won’t help, and may
actually harm, the plant. The needs of the plant need to be balanced. If
there is plenty of sunlight, the plant can use more water and
fertilizer. Under low light levels, the plant doesn’t require much
fertilizer and the nutrients stay in the soil where they can build up
and may eventually burn roots.
Also, excess water can drown roots. Therefore, it is important to do a
good job of watering and fertilizing during the winter. Only water when
the soil is dry ½ inch deep in the pot. Eventually you can learn to
judge whether a plant needs water just by weight. Also, reduce or
eliminate fertilizing during the winter months. If the plant still looks
thin in the spring, cut it back so it can put out new, thicker growth.
Also, knock the plant out of the pot in the spring and make sure it
isn’t root bound. If it is, move it up to a larger pot.