Feeding balcony plants through the year

A plant in the ground sends its roots out until it finds what it needs. A plant in a pot has only the mix you gave it, and every watering rinses a little of that out through the drainage holes. After a few months, fresh potting mix has little food left in it. Feeding puts that back. It is not complicated, but timing matters more than the product: the right feed at the wrong time of year does more harm than no feed at all.

What a feed actually does

Every fertiliser label carries three numbers, such as 19-19-19 or 10-26-26. They are the share of nitrogen, phosphorus and potassium, always in that order. Nitrogen drives leaves and green growth. Phosphorus supports roots and flowering. Potassium helps a plant handle heat, dry spells and disease, and improves flowering and fruiting. A balanced feed, with the three numbers roughly equal, suits foliage plants. A bloom feed, lower in nitrogen and higher in the other two, suits bougainvillea, mogra, hibiscus and anything grown for flowers.

Organic feeds work more slowly and more gently. Vermicompost and well-rotted compost improve the mix as well as feeding it, and it is hard to overdo them. Bone meal adds phosphorus, and wood ash adds potassium. Mustard or neem cake, soaked and diluted, is a strong nitrogen feed that many gardeners in India swear by, but it smells for a day or two, which matters on a balcony next to the living room. We usually combine a monthly handful of compost with a liquid feed in the growing months.

A feeding calendar

February to May is the main growing season. As the days warm, give every pot a top dressing of one or two handfuls of vermicompost, scratched lightly into the surface and watered in. From March, add a liquid feed every two to three weeks, diluted to half the strength on the label. Half strength, more often, is safer in pots than full strength once a month. In April and May, feed in the evening or early morning, never onto a pot that has dried out in the afternoon heat; water first, then feed.

During the monsoon, stop or cut right back. Rain flushes feed straight out of the pot, the mix is often wet for days, and soft new growth is exactly what fungus and mealybug like. Resume at half strength when the rains ease in September and feed through October. In Delhi NCR, stop feeding in November; plants barely grow through a cold, foggy December and January, and feed then just builds up as salt. In Bengaluru and Mumbai, winters are mild enough to keep a light monthly feed going for plants that are still putting out new leaves.

Feed a plant that is growing, never one that is struggling. A drooping, freshly repotted or pest-hit plant needs its roots and leaves put right first; fertiliser only adds stress.

Signs of too much

Overfeeding is more common on balconies than underfeeding. Look for a white or yellowish crust on the mix surface or on the rim of a terracotta pot, leaf tips and edges that turn brown and crisp, and lower leaves that yellow and drop even though watering is right. Another sign is lots of soft, pale, floppy growth that aphids find quickly. On flowering plants, too much nitrogen gives you a lush green plant with no buds.

The fix is a flush. Take the pot somewhere it can drain freely and pour through slowly about three times its volume in water, a little at a time, so the salts wash out of the drainage holes. Scrape off any crust on the surface, then leave feed out for a month. Hard tap water, common across much of India, adds its own salts too, so a monthly flush is a good habit even for pots you feed carefully.