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Pruning & Propagation of Salvias
NOTES ON PROPAGATION :
Salvias are reasonably easy to propagate and by taking cuttings it is by far the best and quickest way to obtain multiple plants, it also ensures that the species you are dealing with comes true to form.
Best times are generally Spring, Autumn and Winter for large leaf varieties, ( they don’t transpire as much moisture when it’s cool).
Spring for most other varieties, especially the herbaceous Salvias ( before they run up to flower).
Small leaved Salvias are best taken in Spring and Summer or when the sap is “running” If taken in the cooler months, without the correct bottom heat or perlite mix, these small leaf varieties just sit and sulk, so the warmer months are more suitable for these types of Salvias
Tip Cuttings: Tip Cuttings are the young new growth, where stems have not hardened too much (stem flexible without snapping).
Take a cutting approx 10-12cm from the tip, strip the bottom leaves, remove any flower buds and remove the growing tip. This will encourage new shoots, encouraging the plant to become bushy. On large leaf varieties, cut the leaf in half ( again so they don’t transpire too much)
Cut through or immediately below the node. This is where you’ll find the growing cells. This is very important in all of the larger growing Salvias as they have hollow stems. If taken internodely, they won’t strike. If the Salvia has long spaces between the nodes, then you’ll need a deeper pot. Some of the small leaved varieties can be cut between the nodes as their stems are still green enough at this stage.
Once you’ve taken your cuttings, put them in water while you finish preparing all your cuttings ( this keeps them fresh). When ready, dip the cutting into cutting gel/ powder which helps to promote new root growth.
We’re finding that the cutting mix should be a mix of perlite/ vermiculite and potting soil approx a ratio of 70/30. This will be a dirty mix. The perlite helps to keep the mix aerated. This is really important in the cooler months when cuttings can easily rot. Most cuttings root a lot easier and a lot faster.
You can place 1 cutting in a small pot or multiple cuttings in a wider squat pot if you don’t have the room for multiple pots. By cramming lots of cuttings into 1 pot, they all seem to create a micro climate which helps and protects each other.
Place pots in a sheltered position out of the wind ans direct sun – this allows them to settle. After a few days, place the small leaved varieties out in a sunny position and keep the large leaved varieties in the shade. If possible place them all on to some soil or place some soil in the base of the tray – this seems to help pull the roots down to the bottom of the pot. When roots are showing out of the pot, then it’s time to pot up the plants. Gently tape them out, so you can tease the roots apart gently and carefully. Use a good aerated potting mix which will hold the water in summer but not drown the plant in winter.
The cutting mix can be reused time and time again without any contamination or problems to the cuttings.
Side Shoots: Small side shoots and young growth from the base of the plant can also be taken , this applies to all bushy, herbaceous and tall shrubby species. Often these are best taken with a heal – this is when you carefully break the shoot off the main stem, a small piece of the stem will stay with the shoot – see diagram.
Division: This is done with herbaceous plants that have basal clumps. These can be divided after winter and all frosts are over, when the new shoots start to appear. Dig up or tap out the clump from a pot; using a sharp knife or spade, slice the clumps either in half or quarters, depending on size, making sure there are enough shoots and roots to each clump you want to divide and a good quantity of new shoots.
Clean away any dead stems, shoots ans roots. Dust the cut area with rooting powder, place in the new position or pot, fill with soil, firm down and water in thoroughly, so now you should have 2 – 4 new plants.
Layering: This is an easy way to increase your plants with those Salvias that are naturally procumbent along the ground, or those plants that produce long shoots that can be carefully bent down to the ground.
Some People like to “nick/ wound” the stem, which helps to promote roots at this point, white others just cover a section of stem and wait for it to root, or bury nodes ( or elbows) – these nodes naturally form roots when they touch the ground.
When the stem is well rooted, then the stem can be cut and potted up or planted in the garden.
Seeds: While this method may be a good way to increase your stock en masse it is not always the best method if you are wanting a plant variety to come ‘true’. As with all seed, there is always a chance of cross pollination.
Cross pollination can lead to many varied cultivars and hybrids. Not all salvias cross, there are many species that do come true from seed.
Sow seed in Spring to Autumn, in friable soil, sow seed into pots with a very good seed raising mix. Sow seed directly on top of soil, DON’T cover with soil, Salvias need light to germinate. Cover pot with fly wire to protect germinating seed from the ‘Midnight Munches’.
Water either with a dose of Epsom Salts – 1tsp in 1 Lt spray bottle, allow the mixture to dissolve, then spray immediately after sowing, then again once or twice before they germinate. The magnesium helps to overcome the dormancy.
Smokey water is also used to help germination – used in the diluted form Regen 2000 Smoke Master solution from TREEMAX. This is often used by nurseries and the Botanic gardens to over come dormancy in difficult species.
NOTES ON PRUNING
Pruning Salvias is very easy an can be done at any time of the year. “When you have time”, this is true if you live in the suburbs, but if you live in the country or live in a cold area which could be frost prone, then a little more care is needed.
The rule of thumb is to” always cut to a bud”, that looks as if it’s growing or about to shoot. Salvias put on new growth at the base of the stems as well as where you’ve cut the stem. This is especially true of the small leaf Salvias and perennial Salvias.
There are basically 4 types of Salvias: Tall Salvias, perennial Salvias, small leaf bushy Salvias and clumping Salvias – these can be herbaceous or biennial and usually have rosette type growth. They don’t all have the same method of pruning.
Small Leaf Salvias: can be cut down to half or lower if they are actively growing, but certainly not cut to the ground. If in a frost prone area, then just tip prune and leave any pruning until after the frosts are past. They need to be regularly pruned to keep their compact shape and keep those flowers coming.
Don’t worry about cutting off the flowers, they’ll be back in about 3-4 weeks time.
If the plant is straggly and has about 2 or 3 stems, cut 2 stems back to lower nodes and leave the other one. Wait until the stems begin to shoot before cutting down that last straggly stem. Often if you cut all the stems down all at once – especially if too severely, then the plant can go into shock and die.!. This method ensures that you don’t loose your plant when pruned.
Tip pruning helps to create more compact growth, this can be done at any time after planting out. Most salvias can be pruned back by 1/3 after flowering, removing spent flowering stems as they finish which can result in a second flush of flowers.
These include the greggii/ microphylla group, ‘Cookie’, Sth African Salvias, flocculosa, setulosa, coccinea group, ‘Superior Purple’, ‘Josh’, ‘Silkes Dream’, ‘Penny’s Smile’ etc.. and many other small leaf varieties
When to prune small leaf Salvias?. approx twice a year. Usually in the Autumn, when they are looking straggly after Summer – it’s a good time to clean up the whole plant, get rid of any weak and dead little twigs and any old growth.If you are in a cold area, then just dead head and leave the real pruning until all frosts are over, then prune back to a good bud. After cleaning up the plants, it’s a good opportunity to manure and mulch, as the plants are still growing and need some nourishment for the winter growth and a new flush of flowers.
And again in Spring. The new growth should be taken down by half. This ensures that the resulting new growth will be more sustainable for the upcoming hot weather. If you leave that new Spring growth, you’ll find that it’ll be the first to wilt when we have those hot days in October.
Perennial Salvias These are usually plants with tall straight stems that come directly out of the ground, they produce new shoots at the base. These can be cut down to the ground, only after new shoots have appeared. These plants don’t need touching again until late Summer coming into Autumn, when they need cutting down again.
These would include: Bog Sage, ‘Bethelii’, ‘Joan’, leucantha varieties, ‘Violet Eyes’, ‘Winter Red’, urica, and many others.
Herbaceous Salvias This type of pruning applies to all rosette. clumping Salvias including the biennial Salvias from the Middle East/ Turkey etc.. As this group send up one or more spikes of flower stems, these can be cut down after they’ve finished flowering or in Autumn. I like to leave a bit of a stem ( unsightly as they look), so you know where they are ( you don’t accidentally dig them up and can keep an eye on snail and slugs). When the new growth is about to appear, even a clouch of fly wire over the plant will help to protect the new shoots from those midnight feast until the growth is strong enough to withstand their onslaught.
These include: the nemerosa/ suberba/ x sylvestris group, Clary Sage, desoleana, indica, argentea,’ Rubin’, aethiopsis, eigii etc..
Tall Salvias These are the only group that is usually pruned after they have finished flowering. As these Salvias start flowering in Autumn, through Winter into Spring, many of the early flowering Salvias e.g. mexicana ‘Limelight’ can now be pruned and the later ones, pruned in early Summer, before it gets too hot for any of the new shoots.
Take out the old tough stems and leave the new shoots that are coming up from the base. If there are no basal shoots, then cut down to a node where you think there are buds – about 1/2 to 3/4 down the stem. New shoots should begin to show in a few weeks. If you are unsure, then adopt the above policy of cutting 2 stems and leaving 1 stem, then cutting that down when the others have begun to shoot. When the new shoots begin to appear, you can then see if you want to prune them down some more or just leave the stems and new growth.
As these stems become very woody after some years, it is necessary to almost prune them to the ground to promote good fresh strong stems to take over. But again if unsure, adopt the 2 stem, leave 1 stem policy.
If in a cold or frost area, these tall Salvias may have been frosted, leave the blackened mess until after the frosts have passed. The blackened mess will protect the new shoots, obviously clear away all blackened parts when the weather begins to warm up.
If in these cold and frosty areas, these tall Salvias need protection. – Plant in among or next to other hardy shrubs and trees, which will give protection, plant under deciduous trees- the tracery of the branches helps to break the frost. Plant near brick pathways and paved areas or areas that will absorb the heat – not concrete, as concrete is cold and reflects the heat/ sun.
These include: iodantha, ‘Bluebird’, ‘purpurea’, involucrata spp, ‘Timboon’, ‘Romantic Rose’, karwinski group and many others
All Salvias need pruning to keep them tidy and sustainable to get them through the next hard season of hot summer weather or cold, windy (sometimes, occasionally) wet winters.