Propagating Gypsophila: Seed, Basal Cuttings and Why Division Fails

Do not try to divide an established plant

This is the first thing to know, because dividing clumps is the standard way most gardeners increase a perennial and it does not work here. A perennial gypsophila makes a thick fleshy taproot going straight down, sometimes two feet or more, with a single woody crown at the top. There is no clump of separable growing points to pull apart, and splitting the crown leaves two wounded halves with a broken root apiece.

The same fact rules out moving an established plant. A gypsophila can be lifted successfully in its first year, with difficulty in its second, and effectively not at all after that. Every year you leave it, the taproot goes deeper and the chance of getting enough of it out drops. Decide where it goes before you plant it and treat that decision as permanent.

If a plant genuinely must be moved, do it in early spring just as growth starts, dig a trench two spade depths deep well outside the crown, and lift it with as much of the taproot as you can get. Cut the top growth back by half at the same time to reduce demand on the damaged root, and expect it to sulk for a full season even if it lives.

Basal cuttings in spring

This is the reliable way to increase a perennial you already have. In spring, when the new shoots pushing from the crown are about three inches (8 cm) long and still soft, cut a few of them right at the base where they join the woody crown, taking a sliver of that older tissue with each one if you can. Shoots taken with a heel of firm wood root far more readily than plain soft tips.

Trim each cutting to two or three inches (5 to 8 cm), strip the lower leaves, and insert them round the edge of a pot filled with half and half sharp sand and a soil based compost, with a little added lime. Water once, then keep the mix barely damp. Gypsophila cuttings rot far more readily than they dry out, so a closed propagator with condensation running down the inside is the wrong environment for them.

Kept in bright shade at around 65F (18C) they root in three to four weeks. Pot each one into a deep pot as soon as roots show at the drainage holes, because they begin making their taproot immediately and quickly outgrow a shallow container. Grow them on through their first summer in the pot and plant out in early autumn or the following spring.

1. Take the shoot from the crown, not the stem tip Cut where the young shoot meets the old woody base, easing it off with a slight tug and a knife so it comes away with a heel. These root at roughly twice the rate of tip cuttings.
2. Use a gritty, limy, open mix Half sharp sand and half soil based compost with a scattering of ground limestone. Peat based seed-starting mix holds too much water and the cuttings blacken at the base within a fortnight.
3. Keep them airy, not humid Bright shade, no lid, or a lid propped open. Wipe condensation off any cover daily. The usual failure with these cuttings is rot, never wilting.
4. Pot on deep and early As soon as roots appear at the base of the pot, move each cutting to its own pot at least five inches (12 cm) deep. A taproot that hits the bottom of a small pot and turns kinks permanently.

Saving and sowing your own seed

Both kinds set seed freely and it is worth saving, particularly from the annual, where a home saved packet lets you sow a short row every three weeks without thinking about the cost. Stop cutting two or three plants in late summer and leave their sprays to ripen. The seed capsules go from green to a dry papery brown and the whole spray becomes crisp.

Cut the dry sprays into a paper bag, leave them somewhere airy for another week, then shake and rub them through your fingers over a sheet of paper. The seed is small, hard and dark and separates from the chaff easily if you tip the paper at a slight angle and let it roll. Store it dry, cool and dark in a paper envelope, never in plastic, and it stays usable for three or four years.

Seed saved from a plant grown in a mixed bed of one kind of gypsophila comes acceptably true. Color can vary a little between seedlings, particularly with pink flowered stock, and the odd plant will be less double or less strong than its parent. Sow a few more than you need and pull the weakest at thinning time.

Self sown seedlings appear readily around a happy plant on gravelly ground. They are worth using: transplant them while they still have one seed leaf and a single unbranched root, at which stage they move perfectly well, and never later.

Growing on the new plants

Whether from seed or cuttings, young gypsophila is at its most vulnerable in its first autumn and winter, and the danger is wet rather than cold. The plants are perfectly hardy but a young crown standing in cold wet compost through the winter rots. Keep first year pots against a wall where they stay dry, raised on pot feet, and reduce watering to almost nothing from early autumn.

Plant out in spring rather than autumn if your winters are wet. Give each plant its full two to three feet (60 to 90 cm) of space at planting, set the crown very slightly proud of the surrounding soil so water runs away from it, and spread coarse grit right up to the stems. Do not add compost to the planting hole.

Expect little from a new perennial in its first summer. It should make a modest mound of foliage and a taproot, and the season it looks disappointing is the season it is doing the work that gives you a plant lasting a decade.

Keep a note of which parent plant each batch of cuttings came from and the date you took them. Rooting rates vary a great deal between individual plants, and after two seasons you will know which one in your garden is worth propagating from.