The herb packets at the supermarket are propagation material sold by weight. A few stems, a glass of water, and a bright windowsill turn one purchase into a permanent supply - for the herbs that cooperate.
Nora Finch
Soft-stemmed herbs root readily in water: basil and mint are nearly foolproof, with success rates close to total from fresh stems. Oregano, thyme, rosemary, and sage - the woody Mediterranean crowd - can root from the softer green tips but take several weeks and fail more often, so take extra cuttings of those and consider it a bonus when they strike.
Skip cilantro, parsley, and dill: they are short-lived plants that want to grow from seed, and cut stems almost never root usefully. (Cilantro sold with roots attached - common in Asian grocers - is the exception: plant it directly.) Spring onions regrow from their root ends in water, which is a different trick but the same free-food spirit.
Choose the freshest, perkiest stems in the packet - limp ones can revive, but firm ones root faster. Cut each stem to 10-15 centimeters, snipping just below a node (the bump or joint where leaves emerge): that node is where roots will form, and a cut just below it puts the rooting zone in the water.
Strip the leaves from the lower half of each stem - submerged leaves rot and foul the water - and keep two to four leaves up top. With basil, pinch off any flower buds; a flowering stem puts its energy into seeds instead of roots. Take twice as many cuttings as you want plants, because redundancy is free.
Stand the cuttings in a glass with 5-8 centimeters of water, nodes submerged and leaves clear of the waterline, on a windowsill with bright indirect light - hot direct sun cooks cuttings in a glass. Change the water every two or three days; stale water breeds the bacteria that turn stems slimy, which is the main way water propagation fails.
Basil and mint show white root nubs in 5 to 10 days; the woody herbs take two to six weeks. Wait until roots reach 3-5 centimeters with a few branches before potting. Any stem that turns brown or slimy comes out immediately so it cannot spoil the water for the rest.
Water-grown roots are brittle, so handle gently. Fill a small pot (with drainage) with regular potting mix, make a hole with a finger or pencil, lower the roots in, and firm the soil lightly around the stem. Water thoroughly, and keep the soil consistently moist - not soggy - for the first two weeks while the roots adapt from water life to soil life.
Expect a brief sulk: a day or two of drooping after transplant is normal, and they perk up as the roots take hold. Keep new pots out of harsh direct sun for the first week, then move basil to your sunniest sill (it wants 6+ hours) while mint tolerates less. Mint gets its own pot, always - it conquers any container it shares.
Once a transplanted herb is growing visibly, harvest from the top, not the sides: pinch or snip just above a leaf pair, and the stem splits into two new branches at that point. Regular top-pinching turns a single basil stem into a bushy plant; pulling leaves from the bottom up produces a bare stalk with a tuft on top.
Never take more than about a third of the plant at once, pinch flower buds the moment they appear (flowering ends the leaf production and turns basil bitter), and feed potted herbs a half-strength liquid fertilizer monthly in the growing season. A single grocery packet, propagated and pinched well, supplies a kitchen indefinitely - and each pruning session yields new cuttings to repeat the cycle.
Usually stale water or submerged leaves rotting. Change the water every two to three days, strip everything below the waterline, and start from the freshest stems in the packet. Cuttings that were refrigerated to wilting before you started also fail more often.
Not for basil or mint - they root enthusiastically in plain water. Rooting hormone meaningfully helps the woody herbs like rosemary and sage if you propagate those in soil, but it's an optional upgrade, not a requirement.
Basil and mint will live in water for months if you change it regularly and add a drop of liquid fertilizer every few weeks, but they grow leggier and less flavorful than in soil. Water is the nursery; soil is the home.
Once it has put out several new leaf pairs in soil - typically four to six weeks after potting. Harvest by pinching the top above a leaf pair, take a third at most, and the plant rebuilds quickly.
