Gadenin日本語Get the appA bought bunch is a bag of cuttings
Watercress roots so readily from stem cuttings that a bunch bought for a salad is effectively a packet of plants. The stems carry a bud and a set of dormant root initials at every leaf joint, and put in water those joints push white roots within days. There is nothing clever to do and no rooting hormone involved; the plant does this in a stream as a matter of habit.
This is genuinely better than starting from seed for a home pot. Watercress seed is tiny, needs a permanently wet surface to germinate, and takes several weeks to make a plant worth cutting. A rooted cutting is a full plant in half the time, and you can start one at any point in the growing season instead of waiting for a sowing window.
- Choose the freshest bunch you can find Look for firm stems and dark, unblemished leaves. Bunches sold standing in water or with the roots still attached root fastest. Yellowing or limp bunches have been off the plant too long and often rot instead of rooting.
- Pick out the strongest stems Select six or eight stems that are thick, firm and at least 4 inches (10 cm) long with several leaf joints. Thin, stringy or flowering stems are not worth the jar space.
- Trim just below a leaf joint Cut each stem cleanly a few millimeters below a joint, because that is where roots emerge fastest. Strip the leaves off the lowest inch or two so no leaf sits under the water.
Root them in a jar on a bright windowsill
Stand the trimmed stems in a jar with about 2 inches (5 cm) of cold tap water, deep enough to cover the bare lower joints and no deeper. Put the jar somewhere bright but out of direct midday sun, at ordinary room temperature of 60 to 68F (15 to 20C). Change the water every day. That single habit is what separates a jar full of white roots from a jar of rotting stems, and it is the same habit the growing pot needs later.
White roots normally appear at the submerged joints within four to seven days and are an inch or more long by day ten. Wait until each stem has several roots at least an inch (2.5 cm) long before potting. Cuttings potted the moment the first root appears often stall, because a single short root cannot support the leaves once the stem is in compost.
| Day | What you should see | What to do |
|---|---|---|
| Day 1 | Stems standing firm in fresh water | Change the water |
| Days 2 to 4 | Small white bumps at the submerged joints | Change the water daily |
| Days 5 to 7 | Visible white roots, a quarter inch or more | Keep changing; leave them alone |
| Days 8 to 12 | Roots an inch (2.5 cm) or longer, several per stem | Pot them up |
| Any day | A stem gone soft or brown at the base | Remove it and change the water immediately |
Do not add feed to the rooting jar. Nutrients in still water encourage bacteria and algae far more than they help the cutting, and a cutting has everything it needs in the stem until it is potted.
Potting the rooted cuttings
Fill an 8 inch (20 cm) pot with a firm, heavy compost, water it thoroughly from the top, and plant three or four rooted cuttings evenly spaced with the lowest leaf joints an inch below the surface. Burying a joint or two gives you extra roots and a plant that stands up rather than sprawling. Firm the compost around each stem so it does not float loose when the pot goes into water.
Then stand the pot in a tray with an inch or two (3 to 5 cm) of tap water and keep it out of hard sun for the first week while the water roots convert to soil roots. Roots grown in water are more fragile than roots grown in compost and there is always a short check. After a week in shade, move the pot into good light and start the routine of changing the tray water every day or two.
- Plant several to a pot Three or four cuttings in an 8 inch pot give a dense clump you can cut from properly. A single cutting takes most of the season to fill the same pot.
- Keep the tops dry, the roots wet The compost surface stays above the tray water. Leaves and stems lying in standing water rot; only the roots and the buried joints should be wet.
- Pinch the tips after two weeks Once the cuttings are growing away, pinch out each growing tip. Every pinch doubles the number of shoots, and a pot pinched twice early carries far more leaf all season.
Dividing and layering an established clump
An established pot also propagates itself. Watercress stems that sprawl across the compost root wherever a joint touches the wet surface, so by midseason a clump is full of independently rooted pieces. Tip the pot out, tease the mass apart into sections each with its own roots and several shoots, and pot them up separately. It is the quickest way to turn one tired pot into two fresh ones.
You can also layer deliberately without disturbing anything: press a long stem down onto the compost, pin it with a bent piece of wire, and it will root at the joints within a fortnight. Then cut the rooted section free from the parent and pot it. This suits late summer, when you want a fresh young pot for autumn but do not want to check the plant you are still cutting from.
Divide and take cuttings in spring or early autumn when temperatures are between 50 and 68F (10 to 20C). Cuttings taken in peak summer heat rot in the jar far more often than they root, and divisions made then sulk for weeks.
Keep a note of what rooted and how fast
Write down the date you put a bunch in a jar, where the bunch came from, and the date you saw the first roots. Bunches differ enormously in how fresh they are, and after two or three attempts your notes will show which source roots reliably in a week and which one you should stop bothering with.
Record the potting date too, and how many of the cuttings survived it. If you regularly lose cuttings after potting, the note will usually point at potting them too early with a single short root, or at putting them straight into full sun. Both are easy to correct once you can see the pattern written down.