Gadenin日本語Get the appWhy the autumn cuttings matter
The tender shrubby salvias are the ones worth the trouble, because they are the ones that may not come through the winter. They are also, conveniently, the easiest plants in the garden to root. A batch of cuttings taken in early autumn, kept frost free over the winter and potted up in spring costs you an hour of work and removes the risk entirely. If the parent survives, you have spare plants to give away or to fill a gap; if it does not, you have lost nothing.
Take the cuttings before the first frost and while the plant is still in active growth, not after cold weather has already knocked it about. Shoots that have been chilled root slowly and rot more often. Aim for a point in early autumn when the plant is still flowering freely and the nights have not yet turned cold.
Take more than you think you need. They take up almost no space, the success rate is high enough that you will end up with spares, and spares are exactly what makes this an insurance policy rather than a gamble.
Taking and rooting the cuttings
The material to look for is a non-flowering side shoot, firm rather than floppy, about three to four inches (8 to 10 cm) long. Flowering shoots root badly because the plant is committed to the flower rather than to making roots. If every shoot on the plant is flowering, take one anyway and remove the flowering tip.
Salvia cuttings do not need rooting hormone, though it does no harm. They root in two to three weeks in mild conditions, and the first sign is new growth at the tip rather than anything you can see below. Resist pulling them up to check. A gentle tug that meets resistance tells you what you need to know.
- Cut a non-flowering shoot in the morning Take three to four inches (8 to 10 cm) of firm side shoot, cutting just above a leaf pair on the parent. Morning material is turgid and wilts far less. Put the cuttings straight into a bag out of the sun.
- Trim below a leaf joint and strip the lower leaves Recut cleanly just below a leaf pair, then remove the leaves from the bottom half of the cutting. Leave two or three leaves at the top, and halve any very large leaf to cut water loss.
- Insert into a gritty, free-draining mix Use about half potting mix and half perlite or sharp sand. Push several cuttings around the edge of a small pot so the bases sit against the pot wall, where drainage and warmth are best. Water once from below.
- Keep bright, frost free and only just damp A windowsill out of direct midday sun, a cold frame or an unheated but frost-free greenhouse all work. Salvias rot under a sealed propagator lid, so give them air rather than humidity. Root in two to three weeks.
- Pot up individually once rooted When new growth appears at the tip and the cutting resists a gentle tug, move each one to its own three-inch (8 cm) pot. Pinch the growing tip out to force branching from the base.
- Overwinter cool and dry, plant out after the last frost Hold the young plants at around 45F to 50F (7C to 10C) with just enough water to stop them shriveling. Harden off over a fortnight in spring and plant out once the last frost has passed.
Label every batch with the parent plant and the week you took it. When one position or one parent gives you a much better strike rate than another, the label is the only way you will ever know.
Spring cuttings from the new growth
The same technique works on soft new growth in spring, and in some ways it works better. Spring cuttings root in as little as ten days, grow away strongly through the summer, and give you a flowering plant in the same season. What they do not do is protect you from the winter, because the plant has already had to survive it.
Use spring cuttings to increase a plant you like or to fill out a planting, and autumn cuttings for insurance. Many gardeners do both, and the two batches serve entirely different purposes.
Soft spring material wilts fast. Take it early in the morning, keep it in a sealed bag until you get to the potting bench, and get it into the compost within an hour. A wilted cutting will often still root, but it takes twice as long and a good many of them fail.
Dividing the hardy border kinds
The hardy herbaceous salvias increase by division rather than by cuttings, and they need dividing anyway every three or four years to stop the center of the clump going bare and woody. Do it in early spring as the new shoots are just showing, when you can see what you are working with and the plant has a full season ahead to re-establish. Autumn division is possible but sets the plant into a wet cold season with damaged roots, which is exactly the combination that rots salvias.
Lift the whole clump with a fork, shake enough soil off to see the structure, and pull or cut it into pieces each with a good share of roots and at least three or four visible shoots. Discard the old woody center entirely; it is the least vigorous part and it will not improve. Replant the outer sections at the same depth immediately, water once, and keep them just damp until you see new growth.
The shrubby kinds do not divide. They have a single woody base rather than a spreading crown, and attempting to split one generally kills it. Cuttings are the only route for those.
| Method | Best time | Suits | How long to a plantable plant |
|---|---|---|---|
| Autumn cuttings | Early autumn, before frost | Tender shrubby kinds, as winter insurance | Rooted in two to three weeks; plant out after the last frost |
| Spring cuttings | Spring, from soft new growth | Any shrubby kind, to increase stock | Rooted in ten to fourteen days; flowering the same summer |
| Division | Early spring, as shoots appear | Hardy herbaceous border kinds | Replanted immediately; flowers the same year |
| Seed | Late winter under cover | Bedding kinds and some border kinds | Eight to twelve weeks to planting size |
Seed and self-sown seedlings
Many salvias seed themselves freely, and seedlings appear around the parent in spring if you leave the last spikes standing rather than deadheading into autumn. These will not be identical to the parent, because most garden salvias are crosses and the seedlings segregate, but a good proportion of them make perfectly good plants. Lift them when they have four true leaves and either line them out or pot them up.
Deliberate seed sowing is worthwhile for the bedding kinds and for a few of the border kinds sold as seed. It is not worth it for a named shrubby plant you want to reproduce exactly, which is what cuttings are for.
If self-sown seedlings are becoming a nuisance in a small bed, the answer is simply to deadhead the last flush of spikes before the seed ripens. That costs you the seed heads over winter, so decide which you would rather have.