A hanging basket is just a pot with a hanger; the basic care is the same as if the plant were sitting on a table. It still needs appropriate light, water and fertilizer. Just because a fern likes humidity doesn’t mean that it’s going to thrive in a dark bathroom, basket or no.
I recommend hanging your basket directly in front of a window, north-facing or east facing would be best for most foliage plants, since south-and west-facing windows tend to get hot, especially in the summer.
Watering: the easiest way to tell if a hanging basket needs water is to lift it and see if it is heavy or light. Artificial soil mixes (that is, all potting soils) get light when they dry out. If it’s heavy, do not water. If it gets very dry, the soil will shrink away from the side of the pot and most of your water will run down the outside of the soil ball and out of the bottom of the basket–or into the water reservoir in the saucer– instead of wetting the soil. So if the pot is very light, I suggest you take it to the sink and water it several times to get the soil wet again.
If your plant has been in the basket for months (or years!) it is likely that you have more roots than soil in the pot. You need the soil to capture the water and provide a slow release of moisture to the roots. If the plant dries out quickly, that’s a sign that it should be repotted (best done in spring or summer).
Grooming: if your plant is a vine, perhaps the ever-popular pothos or heartleaf philodendron, it grows from the tip of the vine outwards. Your basket likely has five or seven plants in the pot to start with, each growing down to capture light coming in from the side window. Eventually, you may find that the basket looks gangly, with long runners, and few leaves on top. You can best deal with this by pinching. By pinching we mean cutting off the tip of one stem of the vine (with a scissors, or you can literally pinch it off, but a scissors makes a cleaner cut). The vine will respond by eventually sending out a new shoot from just below the point where you made the cut, and usually will also send out one or more shoots further back on the stem. This makes the plant fuller. [The new shoot comes from a dormant bud at the point where a leaf attaches to the stem, so when you make the pinch, don’t leave a long length of stem above the pinch. Pinch close to the leaf.]
I recommend you do this once a month in the prime growing season (say March through October), pinching off about a quarter of the shoots at various heights so that the basket remains full–some of the branching occurs close to the rim, while other shoots branch close to the bottom of the pot. My experience with pothos is that they always just send out the one new shoot without the additional branching, so varying the length of the pinch as described is particularly important for pothos.
Fertilizing: whatever houseplant fertilizer you are using is fine, following label instructions. You don’t need much if any in winter. I like the Jack’s Classic line of fertilizers.
Turn, turn, turn: as with any plant, it will grow toward the light. Since we tend to favor symmetry in hanging baskets, changing which side of the basket faces the window once a week will help to keep it full on all sides. Otherwise, you’ll see a plastic pot and the squirrels will see a lush hanging basket.
by Larry Hurley, Behnke horticulturist