Sylvia Clare’s Column – Propagation

Published: July 31, 2022


Not more plants -the joys of propagation

This is the cry of my husband on a regular basis as the postman brings new packages which set me salivating and rushing down the garden to pot up. I do tend to get carried away with the marketing strategies of many online nurseries, but living on the Isle of Wight means we need to arrange a full day trip to visit many specialist nurseries although we do have some good plant centres on the island, but I always want even more variety. Propagation is the answer and there are a few forms I use. Collecting and sowing seed, taking cuttings and plant division being the main forms.

In our garden of good size, an acre divided up into about 8 -10 rooms, as well as a veggie plot and ‘orchard’ area, you need a lot of plants. I won the argument against a lot of lawn years ago and have gradually encroached on what grass we have until it is more or less just paths. So I need plants and in bulk. I am a dedicated plantaholic even though not a very expert one, and my husband has frequently suggested I go for counselling, but mindful gardening is all I need to get me through whatever else life throws at me. Some ‘aholics’ are worth having though, and the plant version is infinitely preferable to any other I can think of.

So this time of year I am busy splitting and dividing the many plants that flower in late summer and autumn, especially asters, golden rods and rudbeckias. These are plants I especially want multiples of for dotting around the garden, as they are an excellent source of late food for my bees to take into their winter stores. I am already thinking a year ahead for them as the most important focus for my garden. These plants are beginning to push their shoots through and I am just finishing cutting down all the dead stems which I leave through winter for any seed heads to provide bird food and frosted decoration. The asters are my favourites and I mostly collect new England varieties as they have coped well with my free draining soil for several years now, without mildew becoming a problem ever. Septemberrubin and Violetta are both deep and richly coloured varieties and I am gradually spreading them and many others around the plot, letting them form clumps of colour merging into each other as they grow past all the earlier plants that have started to die back, finishing the year with a flourish.

My other favourite for division is primroses. I have many varieties around the garden, Wanda and yellow natives being my favourites, and I allow them to create their own little colonies in various spots. They really do like the banks which our sloping garden provides. I was delighted when I saw Carol Klein extolling their virtues on her cottage garden series. Unlike many, I also like the slightly washed out shades of interbred varieties with soft smoky shades of pink, purple and other more bruised looking colours.

I propagate by digging up these plants and pulling or cutting them into smaller clumps, potting some on to give away or pop into spaces elsewhere, and replacing others back into the original spaces with some new home made compost to feed them. These are all worth dividing at this time of year and they take very well and are ready to pop into spaces at any time later on in the year. I am also popping lots of small pots of bulbs into spaces where gaps become evident as the spring develops.

In spring the other main form of plant acquisition is seed sowing and I have always got a few treats I ordered alongside my annual veg. order. This year I am after pollen and fragrant flowers again of course, but also blooms which will be good for cutting for all our wonderful holiday guests. This year I am going for cornflowers, scabious, cephalaria, nicotiana, salpiglossis and cerinthe. I have my trays of seeds already sown and lined up on our dining room table waiting for room in the greenhouse. The room has large French windows so they get a good amount of light and I turn them daily to encourage them to grow straight and not too etiolated (thin and spindly due to lack of light). Also I have found that brushing the seedlings daily with my hand helps to imitate wind resistance and helps them to develop stronger stems. These will all go out into my greenhouse as soon as it warms up enough, (it has taken forever this year for everyone as well as for me). I can bring out the pots of over-wintering dahlias, geraniums and other frost tender plants and dot them around the courtyard and in front of the house. I don’t think there is ever enough space in a greenhouse for everything, so the ‘not more plants’ comments extend to the growing table of small plants and seedlings I am now storing indoors, just waiting for this endless cold to finally clear and let the growing season really take off. Not more plants, can there ever be such a concept in reality, and I know I am not the worst of my HPS friends.

Now as luck would have it and further extolling the virtues of HPS membership, we arranged a group day trip to Hardy’s cottage plants, to include a workshop on propagation by Rosie Hardy herself. It was wonderful and below is a bullet point list of her top tips, which she generously gave me permission to include.

  • Cleanliness is important for tools, trays and compost to give seedlings maximum chance of surviving.
  • Collect seed in a paper bag and store cool and dark place to simulate dormancy, with full labelling on bag.
  • Sow straight from plant if needs to be sown fresh and check up with seed sowing guides for right conditions for each type of seed (Jellito guide)
  • Do not roll seed in hand -it coats seed with a thin film of grease from hand oils and reduces germination
  • Compost should be 50/50 seed compost and perlite -not vermiculite as this is better for covering but keeps compost too wet. (grit is better with loam composts only)
  • Flatten soil in seed tray, ensure fully moist before sowing, water from fine rose and start flow away from seed tray and move over it so there is no uneven watering.
  • Large seeds improve germination if they are soaked in warm water to rehydrate them and soften outer skin.
  • Large hard black seeds benefit from 5 -10 seconds in boiling water then strained into sieve immediately, taking care to protect your own hands from scalding of course.
  • Prick out earlier than you think – as soon as cotyledons are there, using a dibber, this helps seedlings get away faster than waiting until later on.
  • Too deep trays mean roots have to go further down until they hit a surface which encourages them to branch out and make more robust root system.
  • Make sure you label and date all seed trays.

Cuttings -Tip, Basal, Pup, and Root versions of the technique.

Tip cuttings are from the tips of shoots, basal from the base of plants where new shoots emerge and root are literally pieces of root which then grow on into new plants. Pups are small plantlets which form at sides of parent plants.

General tips:

  • Use hormone gel only, and mainly only for shrub and tree cuttings, not necessary for ordinary cuttings.
  • Check to see if roots are coming through the bottom of pots before moving on into individual pots.
  • Use snips or pruners rather than knives as a knife can crush the shoot whereas a snip will cut cleanly through.
  • Make sure all cutting tools are cleaned between plants to prevent cross infections but also because some plants have chemicals in them which might affect another plant adversely.
  • Place cuttings around edges of pots to ensure they hit a surface which encourages roots branching systems to develop.
  • Make sure parent plants are well watered the night before taking cuttings so they have maximum chance of survival.

Tip cuttings.

  • Always cut to a bud to prevent die back rot which might cause problems to the parent plant.
  • Always take cuttings from healthy plants, a sickly plant can only give you sickly cuttings.
  • Need to be no more than 1½ inch long, and trim leaves to half size, this helps plant get enough water before roots develop and the cutting doesn’t have to work so hard to survive and produce new roots.
  • Take cuttings early in season so there are no flowers forming on stems or tips.

Basal cuttings

  • Good for salvias etc, – break off the little shoots that grow from the base of the plants
  • Clean lower leaves off and not longer than 1 inch or so long.

Pups cuttings

  • Gently detach pups from the parent plant and place on the surface of firmed rooting/seed compost.
  • Keep out of windy or draughty places so their contact with the soil is not interrupted.
  • Leave until roots have naturally formed anchoring plant to compost, excellent for sempervivums, sedums and saxifrages amongst others.

Root cuttings

  • Take from fleshy roots like verbascums, crambe, eryngiums, acanthus and oriental poppies -1 inch long is enough for each cutting
  • Better plants grow from nearer to the crown of parent plant.
  • Make sure you know which way is up by making a slanted cut on the lower side and a flat cut on the top side
  • Slide into individual modules and just leave the tip showing, level with top of compost
  • Top growth will show before new roots grow so that the plant can make food for itself, so leave 5-6 weeks until checking for new root growth

Sylvia Clare

Text and photographs by Sylvia Clare, who has been an HPS member for more than 10 years.