Fast-Growing Vegetables for Containers and Small Spaces

Almost every fast crop in this course grows beautifully in a container. In fact, some grow better in a pot than in the ground, because potting mix is loose and fluffy in a way that heavy garden soil rarely is, and a container on a balcony warms up faster in spring than a bed at ground level.

So if your growing space is a balcony, a patio, a doorstep, a fire escape or a windowsill, everything in this course still applies. This lesson tells you which fast crops fit which pot, how deep each one needs to be, and the two things that are different about growing in containers: the fill, and the watering.

If you get hooked on container growing, we have a whole course on it that goes deep on self-watering tubs, mixing your own fill and growing under lights. For the 30-day plan, this lesson is all you need.

Roots need room to go down, and different crops go down different distances. Match the depth of the pot to the crop and everything else takes care of itself.

20 cm deep is enough for most fast crops. Radish, lettuce, arugula, mustard, spinach, pak choi, chard, turnip and chives are all happy in 20 cm of mix. A standard window box is usually about that depth, which is why a window box is the single most useful container for a fast garden.

30 cm for peas and beans. They root a bit deeper and they need to hold up a plant that climbs, so give them a slightly deeper, heavier pot that won't tip in the wind.

30 to 45 cm for carrots and beets. A carrot grows down, so the pot has to be deeper than the carrot. Short "baby" carrot varieties need about 30 cm. Longer ones want 45. A tall bucket or a deep fabric bag works well.

Width matters less than depth, but the wider the container, the more plants it holds and the slower it dries out. When in doubt, go bigger. A big pot is more forgiving than a small one in every way.

Use bagged potting mixA light, fluffy growing medium sold in bags for containers, usually made from peat or coir, compost and perlite. It drains well and holds moisture, unlike garden soil, which turns to a brick in a pot., not soil dug up from outside. Garden soil is heavy, packs down hard in a pot, drains badly, and often brings pests indoors. Potting mix is designed for containers: light, airy, and holds water without going soggy.

Fill the container to about 2 cm below the rim, press it down gently, and water it well before you sow. Fresh mix is often dry in the middle of the bag and takes a good soaking to wet through.

If you have compost, mix a few handfuls into the top layer. Fast crops don't need much feeding in their short lives, but a bit of compost in the mix means you won't have to think about it at all until the slow crops are on their way. We cover feeding in the lesson on feeding fast crops the natural way.

Here is a simple plan for a small space, using three containers.

Container one: a window box, 20 cm deep, 60 cm long. Sow a short row each of radish, arugula, lettuce and spinach. This box alone gives you the day 30 salad.

Container two: a round or square pot, 30 cm deep. Push four or five bamboo canes into it, tie the tops together, and sow peas around the base. The peas climb the canes. Pinch the tips for shoots along the way.

Container three: a deep pot or bucket, 30 to 45 cm deep. Sow carrots across the surface and a few beets around the edge. Sit this one somewhere it can be forgotten for two months.

If you have room for a fourth, a 20 cm pot of chives will feed you for years. And a tray of microgreens on the windowsill inside is your fastest harvest of all.

A garden bed holds a huge reservoir of water in the soil around it. A pot holds only what is in the pot. So containers dry out much faster, and on a hot, windy balcony a small pot can go from damp to bone dry in a single afternoon.

The fix is simple: check every day. Push a finger into the mix up to the first knuckle. If it feels dry at that depth, water until it runs out of the holes in the bottom, then stop. If it feels damp, leave it. In cool spring weather that might mean watering every three days. In a warm, dry spell it might be every day.

Two things make it easier. A bigger container dries out slower than a small one, so size up if you can. And a layer of mulchA covering laid over the surface of the soil, like straw, dried leaves or grass clippings, that shades the soil and slows evaporation. on top of the mix, even just a thin layer of straw or dried grass, cuts water loss dramatically.

Three quick things about balconies and patios.

Light. Most fast crops want at least four to six hours of sun. Lettuce, spinach and pak choi are happy with less and actually prefer some afternoon shade in warm weather. Radish, peas and carrots want as much as you can give them. Put the sun-lovers at the front and the shade-tolerant greens behind.

Wind. A high balcony can be windy, and wind dries pots out and knocks over tall plants. Put peas against a wall or railing, and use heavier pots for anything that climbs.

Weight. A big container full of wet mix is heavy. A balcony can take a few large pots without any trouble, but if you are planning a dozen, spread them out along the edges near the walls rather than clustering them in the middle. Fabric grow bags are lighter than clay or ceramic for the same volume.

A balcony or a windowsill is a real growing space. Give each crop the depth it needs, fill the pot with proper potting mix, check the water every day, and every fast crop in this course will grow for you.

Here's what to take away from this lesson:

• 20 cm of depth grows most fast crops; peas want 30 cm; carrots and beets want 30 to 45 cm
• Any container with drainage holes is a planter
• Use bagged potting mix, never garden soil
• Containers dry out fast, so check with a finger every day and water when it's dry at the first knuckle
• Sun-lovers at the front, shade-tolerant greens behind, climbers against a wall

You know what to grow, where to grow it, and how fast it will come. The last piece is when. Get the timing right and everything in this course is easy. Get it wrong and even a radish will let you down. That's the next lesson.