Gadenin日本語Get the appWhy a pot suits tatsoi particularly well
Tatsoi has a shallow, spreading root system and a plant that grows outwards rather than upwards, so it never runs out of depth in a container the way a root crop does. A single mature rosette lying flat across the rim of a ten inch (25 cm) pot is genuinely handsome, and it is the easiest way to grow tatsoi clean, because in a pot you can put the water exactly where you want it and there is no soil splash from surrounding ground.
The container also lets you move the plant, and with tatsoi that is worth more than with most greens. A pot can go into afternoon shade during a warm spell to keep the plant flat and delay bolting, and it can be pulled against a wall or under a cold frame when hard weather arrives.
The one thing a container will not forgive is drying out. A tatsoi that goes bone dry once loses its lower leaves and rises out of its flat habit, and it does not fully go back.
Match the pot to the plant you want
Depth matters less than surface area here, which is the opposite of most crops. Six inches (15 cm) of depth is enough for any tatsoi; what the plant needs is room to lie flat without its leaves hanging over the rim into the air, where they dry and burn at the edges.
Any container works provided it drains freely. Check the holes before you fill it, because a pot standing in water through autumn rain will kill tatsoi far faster than frost. Use a peat-free all-purpose potting mix or a soil-based potting mix, never garden soil, which sets to a solid block after a few waterings.
| Container | Minimum depth | Plants | Best for |
|---|---|---|---|
| 8 in (20 cm) round pot | 6 in (15 cm) | 1 plant | One medium rosette on a doorstep |
| 10 to 12 in (25 to 30 cm) pot | 7 in (18 cm) | 1 plant | A full-size flat winter rosette |
| Window box, 24 in (60 cm) long | 6 in (15 cm) | 2 plants, or a baby leaf band | Small pickings close to the kitchen |
| Trough or half barrel, 24 in (60 cm) wide | 8 in (20 cm) | 4 plants | A steady winter supply |
Do not crowd a container to get more plants in. Two full rosettes in a 24 inch (60 cm) trough will out-yield four crammed ones, because crowded plants stop lying flat and start competing upwards.
Watering a flat plant in a pot
The rosette eventually covers the entire compost surface, which makes watering from above both awkward and harmful. Water down one side, with the spout under the leaves against the inside wall of the pot, until it runs from the drainage holes. That gets water to the whole root ball without a drop landing on the leaves.
Better still, water from below once the plant has closed over. Stand the pot in an inch (2.5 cm) of water in a tray for fifteen or twenty minutes and let it draw up what it needs, then tip the tray out so the pot is not left standing. This is the cleanest way to grow tatsoi anywhere, and it is a large part of why container plants come to the kitchen needing only a rinse.
Judge by weight rather than by looking at the surface, which you can barely see anyway. Lift one edge of the pot straight after a thorough soak so you know what full feels like, then lift it whenever you are unsure. In cool weather a 12 inch (30 cm) pot may go a week; in a warm spell it may need water every second day.
Feeding, and carrying pots through the cold
Fresh compost carries a tatsoi for about four to six weeks. After that, every watering is flushing nutrients out of the base of the pot and you need to replace them with a balanced liquid feed every ten to fourteen days, which is roughly twice the frequency you would use in a bed. Stop about four weeks before hard frost.
Roots in a pot are not insulated by the ground, so a container root ball can freeze solid while a bed a few feet away stays workable. The leaves of tatsoi are far hardier than its roots in a pot are, which catches people out: the plant looks untouched and dies from below.
- Group the pots and lift them off cold ground Push containers together against a house wall for the coldest weeks and stand them on wood or bricks rather than on stone or concrete. A group of pots shelters one another and the outer ones take the worst of it.
- Wrap the pot, not the plant A layer of bubble wrap, hessian or straw around the outside of the container protects the roots. Leave the leaves exposed; tatsoi is at its sweetest after frost and covering the foliage warm and damp does more harm than the cold would.
- Sink small pots for the winter Anything under 8 inches (20 cm) across is best buried to its rim in a bed or plunged in a box of dry leaves. Small pots freeze right through in a single hard night.
Records worth keeping for containers
Container growing gives you variables you control completely, so notes pay off faster than they do in a bed. Record the pot size, where it stood, the sowing date, and whether that plant ended up flat or upright. Add how often you watered it in each part of the season.
After a single winter you will know which corner of a balcony or yard keeps tatsoi cropping through the cold and which one freezes, and after two you will know exactly which pot size holds enough water for your conditions without you having to think about it.