My “mini palm” looks like it has mites – I have sprayed it with a weak soapy solution, but it doesn’t seem to be helping.
There are many species of indoor palms and since you don’t specify which one this is, I’m going to speculate that it’s the popular Areca palm or Butterfly palm, of the Family Arecaceae, Chrysalidocarpus lutescens. In their tropical natural habitats, Areca are relatively fast-growing and form clumps that naturally multiply on their own. However, Areca palms can present the home grower with multiple challenges that often interconnect.
I notice from the picture that some of your palm’s leaves are yellowing. They aren’t a deep rich green. Arecas are very heavy feeders and can develop yellowing leaves in the absence of magnesium and iron. Confined to a pot, the root system needs to have a sufficient supply of water & nutrients in order for the plant to be able to produce energy to grow. A feeding with a slow-release fertilizer, like a 12-4-12, which can be found at your local nursery, would be a way of getting vital macro and micro nutrients to the plant. Always follow the application directions carefully as fertilizer can burn roots and harm your plant if used inappropriatly.
Areca are vulnerable to a whole gamut of insect pests including spider mites, aphids, mealy bugs and white fly. Mites cause damage by piercing the leaves, sucking out fluid & nutrients and can weaken the plant greatly. If you have correctly identified your problem as mites, spraying with either an approved Insecticidal Soap or Horticultural Oil would be a good treatment and should get rid of these pests. Both of these products can be purchased in any good nursery or garden centre. Keep a keen eye out for a second wave of mites and re-treat if needed.
There are a few more tips which will help keep your plant happy and thriving. Areca like more light than the average indoor environment can supply which challenges many growers of this palm – quality and duration of light are important. These plants also like lower-than-average winter indoor temperatures and also higher atmospheric humidity. Moving your plant into the sunniest window location you’ve got and keeping it away from a direct heat source will help. Placing the container on top (not in) of a container containing stones & water will increase the humidity around the plant as the water evaporates.
These plants are a challenge to maintain but the payoff is a beautiful, lush, vibrant palm that can infuse a room with a wonderful touch of the tropics. With continued care and attention to detail, you have every good chance of keeping the palm healthy.
Below is a link to a related Toronto Master Gardener article on indoor gardening of palms.