6. Keep it going: succession, pests and the end of the season
A balcony garden that produces for seven months rather than five weeks is simply one that gets replanted on a rhythm. This is the step that separates a hobby from a supply.
Sow in succession. Every three weeks from March through August, sow another short row of salad, radishes or spring onions in whatever space has just been harvested. Keep a small bag of compost and a few seed packets within reach of the door, because a task that requires fetching things from a cupboard does not happen. When a crop finishes, something goes into that space the same week.
Extend both ends of the season. Broad beans, garlic and hardy salad leaves can go in during autumn and overwinter outside in most of the US, Canada and the UK, giving an early spring crop from pots that would otherwise sit empty. A cheap plastic mini-greenhouse against a wall buys three or four weeks at each end and shelters seedlings from wind.
Handle pests early and mechanically, since balconies are small enough that you can. Aphids come off with a firm spray of water or squashed between finger and thumb; a build-up usually means the plant is stressed or overfed with nitrogen. Slugs and snails do reach balconies — check pot rims and undersides at night, and stand vulnerable pots on a copper-taped tray. Whitefly on tomatoes responds to a yellow sticky trap. Ants farming aphids on a stem mean you deal with the aphids. Resist reaching for sprays on food crops in a space where people sit; hand removal genuinely works at this scale.
Watch for the common failure signs and what they mean. Yellowing lower leaves usually means hunger or waterlogging. Leaves curling upward in heat is normal and recovers by evening. Flowers dropping without setting fruit on tomatoes means heat stress or dry roots — tap the flower trusses daily to help pollination if bees are scarce up high. White crust on the compost surface is mineral salt from hard water and tap feed; scrape it off and water more deeply.
At the end of the season, tip out the annual pots, cut the spent plants up into a small compost bin or the council green bin, and wash the pots with hot soapy water so next year’s seedlings do not inherit this year’s fungus. Store the pots stacked and out of frost — plastic and terracotta both crack over a hard winter. Write down what actually cropped well on your specific balcony and what did not. Two seasons of that note is worth more than any general advice, including this article, because your light, your wind and your habits are the variables that matter.