Propagation

It is Saturday 26th March, the garden is full of Spring bulbs and blossom but, in a curious tradition only we could make up, the clocks go forward an hour tonight and British Summer Time (BST) begins! This means two things, it’s time to plant out Sweet Peas, and time to start propagating the Tradescantias.

By propagating, I really mean dividing or, more accurately, removing a slice from the outer part of the clump. This is the second year of the Collection and I am under an obligation from Plant Heritage to hold not only a main listed plant (an Accession), but also two others of each cultivar. This is known, as in Royal parlance, as an ‘heir and a spare’ (think Princes William & Harry!). It is an insurance policy to ensure the survival of each cultivar by always having a duplicate plant in case one perishes.

In this example, I am going to take a division of Tradescantia (Andersoniana Group) ‘Charlotte’ which is looking very happy, healthy and raring to go. The process I am using leaves 80% of the plant untouched and unharmed, thereby giving it the best possible chance of recovering quickly and growth unchecked.

A small outer section is selected and the hand trowel inserted smartly and vertically, ignoring the loud graunching noise as it cuts through the crown and thick fleshy roots. This can be a little disconcerting and it is only natural to think that irreparable harm is being done but, like other fleshy rooted perennials (Agapanthus, Rudbeckia, Sanguisorba etc.), the plant is programmed to accept the damage as part of life and recovers quickly.

The resulting division is lifted cleanly away from it’s parent and moved to the bench.

This one small piece could easily be divided into four or even six separate small plants, but I am just looking at two for my purposes. If I was propagating to increase stock for sale, as a nursery would, I would be pairing this division down into as many small individual plants as I could and would probably have taken a much larger division to start with, depending on the size of the clump.

Using an old breadknife, I cut the division into half, slicing clean through the roots and crown of the plant.

The mass of roots can clearly be seen in this picture but, remarkably, the plant will hardly notice and has enough growth material intact to carry on and produce new shoots and possibly even flower this year.

This size of division fits neatly into a 1 litre (12.5cm / 5″) pot with plenty of room for a season’s growth. Obviously, smaller divisions would only require a smaller (9cm / 3″ pot).

I pretty much use Melcourt SylvaGrow, peat free compost for all my propagation which includes seed sowing, cuttings, divisions and potting on. I have tried many, many alternatives but keep going back to Melcourt. I occasionally add a pelleted slow release fertilizer if the subject is likely to put on fast growth and requires additional long term nutrient, and sometimes add 20% John Innes or bagged topsoil if I think more ‘body’ is necessary, but I mainly use it straight out of the bag with excellent results.

I find the blend of fine bark, coir and wood fibre is good at retaining water and nutrients, is consistent and, importantly to me, contains no peat or recycled green waste. There is a similar Melcourt product with added John Innes but I find it more convenient (and less expensive!) to add my own in the ratio I want. There is enough base fertilizer to see the plant through the first 6-8 weeks, after which additional liquid feeds are required.

The compost is perfect for a job like this, clean and easily handled, needs not pressure, just tap the pot on the bench to settle the material around the roots, water, label and finish.

The parent plant is simply backfilled with soil and mulched to fill the gaping hole left by the division but in a week or two, the tremendous growth rate of the plant will completely mask the removal.

I will diarise a photo in 2, 4 and 8 weeks to demonstrate the recovery of the parent and growth of the divisions.

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