How to Grow Water Spinach Microgreens at Home

Water spinach microgreens are the young shoots of the plant Thailand knows as pak bung jin. Cut at around ten days they are far more tender than the mature stems: mild, faintly grassy, with hollow stalks that stay crisp. Of the varieties we grow, this is the one that suits a Thai kitchen best, because it takes heat as well as it takes a squeeze of lime.

It is also an easy tray to grow, provided you respect two things: a long soak and a good deal of warmth. Thailand supplies the warmth. The rest of this page covers the soak and everything after it. For the method that every variety shares, start with our guide to growing microgreens at home.

What you need

• Water spinach seed sold for sprouting or microgreens, untreated. Seed packed for field planting is often coated with fungicide and should not be eaten.
• Two shallow trays that stack, one with drainage holes and one without.
• Coco peat or a fine seedling mix, 3–4cm deep. Not garden soil.
• A spray bottle, and a bright spot out of direct sun.

Step 1 — soak the seed for 12 to 24 hours

Water spinach seed has a hard coat, and this is the step that separates an even tray from a patchy one. Cover the seed with cool water and leave it for 12 to 24 hours, then drain and rinse. The seed should look swollen. A standard 25×25cm tray takes about 80 to 100g of dry seed.

Step 2 — sow and weigh the tray down

Fill the drainage tray with damp, levelled medium and spread the soaked seed in a single layer so the seeds touch without piling up. Mist it, set the second tray upside down on top, and put something heavy on that. The weight makes the shoots push up straight and helps strip the seed coats off the leaves.

Days 1 to 3 — keep it dark

Leave the tray covered and weighted. Lift it once a day to mist and let the air change. By the end of day three the shoots should be pale and pushing the top tray up on their own.

Days 4 to 8 — bring it into the light

Remove the cover and the weight. The shoots turn green within a day of bright, indirect light. From here, water from below: pour into the outer tray and let the medium drink it. Water that sits on the leaves is the most common cause of mould, and a still, humid room makes it worse, so keep some air moving.

Day 8 to 10 — cut

Cut with scissors just above the medium once the stems stand upright and the first leaves have opened, usually between day eight and day ten. The tray does not regrow. Use the shoots the day you cut them if you can; they keep a few days in the fridge, dry, in a container.

Cooking with water spinach microgreens

This is where water spinach earns its place. The stems are hollow and crisp, so they hold up to a quick, hot wok where most microgreens would collapse. For a full recipe, see stir-fried water spinach microgreens, pad pak bung style.

• Stir-fry over high heat for under a minute with garlic and oyster sauce. Any longer and the stems go limp.
• Drop into noodle soup after you take it off the heat, so the stems stay crisp.
• Toss raw through som tam for a soft, green contrast to the chilli and lime.
• Pile onto rice with a fried egg.

Eating them raw is fine too. Microgreens are grown in an open tray and cut above the medium, so the safety questions that apply to sprouts do not apply here. Our piece on eating microgreens raw covers it in full.

Grow it, or buy it?

Growing water spinach yourself is cheap and forgiving once you have a tray set up. But a home tray gives you one harvest on one day, and it is hard to time to a dinner. If you want a cut to order, you can order water spinach microgreens from us instead. If radish is the variety you want to learn on first, it is the faster one: see how to grow radish microgreens.