Flowering and decorative plants are one of the quickest ways to brighten a room. To care for them properly, you need to understand the conditions they require to thrive.
A plant is a living organism that goes through a growth period and then a resting phase each year. Knowing that cycle makes a big difference in how you care for it. During the summer growth period, for example, plants need more water and benefit from fertilization. In winter, during the resting phase, they need less water and should not be fertilized.
A plant’s life depends on a few basic conditions: light, air, temperature, water, and soil.
Southeast-facing windows provide some of the best conditions because they get sunlight for much of the day. South-facing windows should be shaded in summer to prevent plants from overheating and drying out. North-facing windows work for low-light plants. Species that need more light — including many herbaceous, semi-herbaceous, and flowering plants — do better in bright spots. Ficus, philodendrons, laurel, and other plants with thick, leathery leaves tolerate lower light levels.
Not every plant needs to sit on a windowsill. Palms and philodendrons can be placed farther from the window, and aspidistra can even do well in a dark corner.
Most houseplants grow better if you can move them outside to a balcony during the summer. Move them only after the threat of frost has passed and, when possible, on cloudy days. Once they’ve acclimated, they can handle more sun and warmer temperatures.
Room temperature matters, too. Many plants struggle with high indoor temperatures in winter; for instance, grafted lemons and oranges often drop their leaves if temperatures exceed 50–54°F (10–12°C), which can stop them from flowering in summer. Avoid placing plants near radiators or stoves. Windowsills can be tricky because cold air from the glass and hot air from heating systems below create poor temperature conditions. It’s better to put plants a little farther from the window on small stands or tables.
Keep the air fresh and not overly dry by ventilating regularly, but position plants so cold drafts from open windows don’t hit them directly.
To prevent the air from getting too dry — which is unhealthy for people as well — mist plants with room-temperature water daily or 2–3 times a week. Misting helps humidify the air, removes dust from leaves, and reduces the chance of pests.
Water for misting and watering should sit in an open container for several hours to reach room temperature and allow chlorine to dissipate; don’t use water straight from the tap or well. When you water, let the water pass through the entire soil mass and drain into the saucer.
Soil is vital because it supplies minerals. Different plants need different soil types, so choose carefully when repotting.
In a city, this is easy: buy the soil you need at a garden center and tell the staff which plants you have. If you make your own mix, you will need turf soil, leaf mold, compost, and peat.
Turf soil forms from decomposed sod collected from old pastures and piled for 1–2 years; it’s excellent and can be used pure or mixed. Leaf mold comes from decomposed leaves gathered in fall. Compost comes from old greenhouse manure that breaks down over 2–3 years. Peat soil results from decomposing peat piles over 2–3 years.
You can sometimes use regular garden soil (the top layer) and add coarse river sand to improve texture and drainage.
For plants with fleshy or thick roots (like palms and ficus), use a dense mix: 3 parts turf soil, 2 parts compost or leaf mold, and 1.5 parts coarse sand.
For plants with well-developed, fast-growing roots (like begonias and fuchsias), use a medium-density mix: 2 parts peat, 1 part leaf mold, and 1.5 parts coarse sand.
Repot most houseplants in spring, just before the growth season — typically in March or April. Don’t move plants into pots that are too large; the new pot should be only slightly bigger than the old one.
When repotting, carefully detach the soil from the pot with a knife to preserve the root ball and keep drainage clear so excess water can escape. Place some broken pottery at the bottom and add a layer of coarse sand. Add soil and set the plant in the pot, making sure the roots don’t bend upward. Do not plant deeper than the plant was previously growing; the root collar (crown) should not be buried. After repotting, some plants may need pruning. Prune to control growth and shape by cutting above an outward-facing bud with a sharp knife. When the repotted plant begins to grow — indicated by swelling buds and new leaves — increase watering. To promote growth, feed the plant with a solution of mineral fertilizers (1–2 grams per liter of water). Ready-made mineral fertilizer mixes are available for purchase, but making your own lets you adjust nutrient levels to the plant’s condition.
To encourage vegetative growth, raise the nitrogen content; to encourage flowering, increase the phosphorus. A standard mineral fertilizer mix is 1 part nitrate, 1.5 parts ammonium sulfate, 2 parts superphosphate, and 1 part potassium salt.
Watering with 1–2 grams of this mineral fertilizer per liter supports normal development. For growth enhancement, use a mix of 2 parts nitrate, 2.8 parts ammonium sulfate, 2 parts superphosphate, and 1 part potassium salt.
Before flowering, switch to a mix of 1 part nitrate, 1.2 parts ammonium sulfate, 3 parts superphosphate, and 1.3 parts potassium salt.
Stop regular fertilization at the end of summer when the plant enters its resting phase. You can still feed recently repotted, unrooted, or sick plants.
Houseplants can be propagated by cuttings, layering, grafting, or division. Plants produced by vegetative propagation keep the parent’s varietal characteristics.
The most common method is cuttings. A stem cutting is a piece of stem with leaves. Take it from a healthy plant, preferably the tip of a shoot, and cut with a sharp knife just below a leaf node. Propagate herbaceous plants from cuttings in spring and evergreen plants in summer.
Root cuttings in pots filled with coarse sand; they don’t need soil until roots form. Rooting is more successful if you cover the cutting with a piece of glass, a cup, or a jar. Once roots appear, transplant the cuttings into regular soil.
If plants aren’t cared for properly, pests can appear. The most common pest is scale insect, which shows up as small, raised yellow spots and attacks oleanders, palms, laurels, and cacti.
Wash plants affected by scale insects with warm soapy water or a tobacco infusion using a stiff brush. Wash leaves and stems, taking care not to let soapy water touch the soil. Rinse the plant with clean water afterward. Repeat the washing after 3–6 days.
For other pests, use anabasine sulfate at 1–2 grams per liter of water, adding 4 grams of green soap or a ready-made soap emulsion (100 grams of soap dissolved in 1 liter of water, mixed with 300 grams of kerosene). Dilute this mixture in 10–12 liters of water.
Thoroughly spray the affected plant with the mixture, and rinse with clean water the next day.
