Gadenin日本語Get the appWhy mizuna suits a container
Mizuna has a shallow, fibrous root system that spreads sideways rather than driving down, so it never fights a pot the way a carrot or a parsnip does. It is also cut-and-come-again, which means a single container keeps producing for weeks instead of giving you one harvest and then sitting empty. For anyone growing on a balcony, a doorstep or a windowsill, it is close to the ideal salad crop.
The trade-off is that a container dries out and runs out of nutrients far faster than a bed, and mizuna punishes both. A pot that goes bone dry once will give you tough, hot leaves for the rest of its life. Almost every container failure comes back to watering rather than to anything more exotic.
Choose the pot by how you intend to pick
Depth is the number that matters, and the minimum is six inches (15 cm). Anything shallower dries too fast to hold a crop through a warm spell. Width decides how many plants you can carry and how long they last, so match the container to your picking style the same way you would match spacing in a bed.
Any container works as long as it drains. Drill or check for holes before you fill it; a pot with blocked drainage in autumn rain will kill mizuna faster than frost ever does. Dark plastic pots in strong sun heat the root zone enough to trigger bolting, so a light-colored or glazed pot is worth having if your spot is hot.
| Container | Minimum depth | Plants | Best for |
|---|---|---|---|
| Window box, 24 in (60 cm) long | 6 in (15 cm) | Sown as a thick band | Baby leaf, shear and regrow |
| 8 in (20 cm) round pot | 7 in (18 cm) | 1 plant | One full-size plant, picked stem by stem |
| 12 in (30 cm) round pot | 8 in (20 cm) | 3 plants | A steady kitchen supply |
| Grow bag or large trough | 8 in (20 cm) | 6 to 8 plants | Enough to cut a bowl at a time |
Do not fill a container with garden soil. It compacts to a solid block after a few waterings and the roots suffocate. Use a peat-free all-purpose potting mix or a soil-based potting mix.
Watering: the one thing that decides the crop
Water when the top inch (2.5 cm) of compost is dry to your finger, and water until it runs from the drainage holes. A splash on the surface wets the top half inch and leaves the roots dry, and repeated splash watering trains the roots upwards where they dry out even faster. In warm weather a 12 inch (30 cm) pot in full sun may need this every day; in cold weather the same pot may go a week.
Check by weight as well as by finger. Lift one edge of the pot after a thorough soak so you know what full feels like, and lift it again when you are unsure. It is a faster and more honest test than looking at the surface, which dries first and tells you nothing about the root ball.
If a pot has gone properly dry the compost shrinks away from the sides and water runs straight down the gap without wetting anything. Stand the whole container in a tray of water for twenty minutes to rewet it from below, then go back to normal watering.
Feeding and refreshing a container crop
Fresh compost carries enough nutrition for roughly four to six weeks. After that, every watering is washing nutrients out of the bottom of the pot and you have to replace them. Start a balanced liquid feed once the plants have four true leaves, and repeat every ten to fourteen days while you are picking, which is roughly twice the frequency you would use in a bed.
- Shear, feed, and let it regrow After cutting a band of baby leaf back to an inch (2.5 cm) above the crown, water thoroughly and give a liquid feed the same day. The regrowth comes from stored energy in the crown and the plant needs the nitrogen back immediately. Expect a second cut in two to three weeks.
- Stop at the third or fourth cut Regrowth gets thinner and more peppery with each pass. When the fourth cut looks sparse, pull the lot, refresh the top half of the compost with fresh material, and sow again rather than trying to nurse it along.
- Move the pot with the season The advantage of a container is that you can move it. Put it in full sun through the cold months and shift it to somewhere with afternoon shade as soon as daytime temperatures pass about 75F (24C). That one move buys several extra weeks before it bolts.
Containers through frost
The leaves of mizuna are very cold hardy, but roots in a pot are not insulated by the ground the way roots in a bed are, and a container root ball can freeze solid while a bed nearby stays workable. Push pots together against a wall through the coldest weeks, or sink smaller ones into a bed or a box of leaves for the winter.
Note in your records how each pot came through the cold, along with its size and where it stood. Container size and position are the two variables you control completely, and a season of notes tells you exactly which corner of your balcony keeps cropping in midwinter.