Terrariums or microgreens

What it is

A closed terrarium is a garden you almost never touch; a tray of microgreens is a garden you harvest in a week. They sit at opposite ends of indoor growing, one a sealed, self-sustaining miniature world, the other a fast, edible sprint, and both are deeply satisfying for completely different reasons.

Terrariums and microgreens are two distinct indoor growing projects often mentioned together. A terrarium is a small garden of slow-growing plants in a glass container, sometimes sealed, sometimes open. Microgreens are the tiny, intensely flavoured seedlings of vegetables and herbs, harvested just a week or two after sprouting and eaten whole. One is a long-lived decorative ecosystem, the other a rapid, repeatable food crop.

The sealed terrarium is the genuinely fascinating one, because a properly balanced closed terrarium recycles its own water almost indefinitely. Moisture evaporates, condenses on the glass, and runs back down to the soil, while the plants and soil microbes recycle nutrients and gases. A well-made one can go for months or even years barely opened, a tiny self-contained water cycle on a shelf. The art is in the balance: too much water and it grows mould, too little and it dries, and choosing humidity-loving plants like ferns, fittonia, and moss that suit the closed, damp environment.

Microgreens are the instant-gratification opposite, and they are remarkably productive for the space. You sow seeds thickly on a tray of compost or a damp mat, keep them moist, and harvest with scissors when the first true leaves appear, often within seven to fourteen days. Pea shoots, radish, broccoli, and sunflower are easy starters, and gram for gram microgreens pack a far higher concentration of certain nutrients than the mature vegetable. They cost a fraction of the punnets sold in supermarkets and need nothing more than a sunny windowsill.