Propagating plants has always been an enjoyable part of my gardening life. There’s nothing quite like the buzz that comes from transforming little brown specks of seed into thriving specimens or encouraging a piece of living plant material to develop roots and replicate the parent.
Seed packets and catalogues offer helpful information on the optimum time and temperature for germination, and even how to proceed, but that should not rule out following your own initiative and experimenting.
When it comes to vegetative propagation, that is, taking a piece of root, shoot, bud, stem or leaf and transforming it into an identical plant, be guided by what the plant has to offer when you examine it.
We are advised for example, that stem cuttings of geraniums (zonal pelargoniums) are best taken in late summer.
Fair enough, that is a sensible time to strike, but you can also encourage them to root in winter, spring or autumn as long as suitable young growth is present. Neither need the range of plants you can propagate be dictated by a lack of greenhouse facility.
I have a few portable trays with domed plastic tops that keep leaf cuttings of streptocarpus going over winter in a moderately-heated conservatory. But the greenhouse does add another dimension!
Mine has a propagating frame one metre square and it’s continuously turning out new plants. It was constructed from recycled pine bookshelves, and a qualified electrician connected the soil warming cable and thermostat. The cable was laid on a sand base and covered with a further 5cm layer of sand.
The rooting medium has a gritty, open quality to encourage air spaces.
Although it is filled with assorted cuttings and seeds throughout the year, the heating facility is only used sparingly from January to March to get important sowings and cuttings under way.
First come the early vegetables and symbolic sowing of onions, then two modular trays are topped up with compost, and a small pinch of leaf lettuce seed goes into each cell.
Once the resultant seedlings have formed a solid plug of root, they’re planted in the greenhouse border alongside established lettuce sown the previous September.
Small trays of summer bedding plants such as begonia take a while to germinate and develop, so they are sown alongside the vegetables, but room is left for stem cuttings of dahlias and chrysanthemums.
As space is freed up, a range of vegetable seeds will pass through the propagator.
It’s far better to give them a flying start by germinating, potting up and growing on, rather than sowing directly into the garden and waiting an age for signs of growth.
From May onward I walk the garden looking for soft shoots of shrubs, herbaceous perennials and herbs that are begging to be rooted. They`re popped into polythene bags with a label then immersed in water before going into the rooting facility. With a little more solar warmth being retained in the greenhouse, the turnover from cutting to rooted young plant is rapid.
Try not to miss out on simple ways of increasing your plant stock as the year unfolds. Existing herbaceous perennials can be lifted and divided up during any frost-free period from November to March. Self-sown plants can be lifted and grouped together for floral effect the next summer – foxgloves for example. Branches of hardy perennial subjects that touch the soil will form roots given the slightest encouragement. I`ve just pegged the lower stems of a thorn-less blackberry, an aucuba and viburnum to the ground.
There`s still time to sow the seeds of favourite herbaceous plants into open drills outdoors and leave them to it until next year. And if you look around the ornamental border there are newly formed seed heads appearing daily. If you collect those of the species they will reproduce true to form. I cannot resist gathering the deep brown seeds of ancient woad (Isatis tinctoria) every year. Nor those of the perennial wallflower Chieranthus cheri.
Deciduous shrubs are so easily rooted that I`m already making a mental note of those to be taken as hardwood cuttings. Viburnum, buddleja, weigela, salix, spiraea and escallonia are all showing suitable stems 30 centimetres long.
Best time to prepare a slit trench with an upright spade is in late October.
Remove all but the top cluster of leaves which just show above the soil when cuttings are planted close together and deeply.
We have a collection of Streptocarpus for indoor display so imagine the pleasure in seeing a brilliant specimen staged by Judith Pottle at Warkworth Show recently. It had to receive the Jenneson Taylor cup as the president`s favourite entry. One of its long leaves could easily have been halved longitudinally and given rise to one hundred new plants. But then of course Judith would have the problem of finding good homes for them all!