Trugg and Barrow’s Garden Diary January 2013
Rain rain rain rain, rain rain, rain rain rain rain rain, rain rain rain, rain rain. The British are known for their pre-occupation with the weather, for gardeners, farmers and others working on the land it is more like an obsession. This time a year ago this part of Shropshire had experienced 9 months of record low rain fall. It then started to rain in April and it has barely stoppped since, making it difficult and uncomfortable at times to do anything out of doors. The answer to these contrasts in the weather probably lies in global warming.
Put simply: As a consequence of the increasing temperatures in the north polar region there is less of a contrast between sub-tropical high pressure and polar low pressure. This causes the polar front jet stream to track further to the south. The result of this is that the jet stream is more likely to be sitting over the U.K. (or even further south).
The polar jet stream is a powerful conveyor belt of winds in the upper atmosphere that circles the north pole. The jet stream marks the boundary between cold polar air from the north and warm sub-tropical air from the south. Weather systems generated on the other side of the Atlantic track eastwards towards northern Europe following the course of the jet stream. If the jet stream is sitting over the U.K. then we get more wet weather, if it is sitting further to the south then we will get drier weather (as in 2011).
Over the last month in the garden we have been covering plants vulnerable to cold weather with thermal fleece. Leaf collecting has been more or less completed, although the water gardens have still got to be tackled. This is always a mauling job due to the difficulty of access. We have also continued cutting back plants in the herbaceous borders. We have spent time decorating Christmas trees for the ‘Big House’ and the church, as well as digging out drains. Drying out clothes has also kept us busy.
Bewitching Witch Hazels.
There is no flower, with the exception of perhaps the snowdrop, that brightens a winter day more than that of the witch hazel or Hamamelis. We are all easily beguiled by their bright display, which is actually made up of floral bracts, the flowers being a rather insignificant cluster. Moreover, descendents of H. mollis, the Chinese species, also offer a spicy aroma that can fill the garden on calm days.
I have fallen so in love with these most accommodating shrubs that I have set myself the task of duplicating an entire collection of over 60 plants. Beyond the sheer enjoyment of these plants there are two reasons for doing this. Firstly, the collection in question has National Collection status so the plants are certain to be of good quality and be representative of the genus. Secondly, although it might be easier to go out and buy a collection of plants, propagating Witch Hazels represents a particular challenge and I am keen to teach myself a new skill.
When I asked more experienced hands about using cuttings, a method that I have more experience of, they all said don’t bother! The more I looked into it the more I found that this was an unreliable method for all but the species. H. mollis, H. japonica and H. virginiana, which will all root from softwood cuttings or layers taken in summer (late June) but they do seem to need some coddling. Cultivars, especially those of H x intermedia, are notoriously unreliable. The best method seems to be grafting and that is the one used in the nursery trade where thousands are produced each year.
Grafting is an ancient method of propagation, known to have been practised by the Romans and in the monastic gardens of the medieval period. It is a form of vegetative propagation which, as with cuttings or layers, avoids the hazard of variable progeny where this is not desired. Unlike a cutting which gardeners attempt to get to form roots on its own; the scion, the cultivar you want to propagate, is attached to a rootstock which already has roots. This rootstock must be a relative. You could not graft a rhododendron onto a palm tree for example. With plants that have been heavily hybridised this can be a problem. With Magnolias, M. kobus, M. campbellii, M. soulangeana and M. denudate are commonly used as rootstocks because they feature so heavily in breeding.
There are other reasons for choosing rootstocks. Rhododendrons all used to be grafted onto R. ponticum because it was amenable to most scions and its vigorous spreading root system gave good establishment. Most roses in this country are budded onto R. laxa as a rootstock which helps control vigour and imparts greater disease resistance in some. However some rootstocks also have disadvantages. R. ponticum is notorious for throwing out suckers (portions of itself) which if not kept in check out-compete the scion which eventually succumbs.
Luckily, Hamamelis are not too fussy about what rootstocks they prefer and can even be grafted onto cultivars or hybrids. The usual rootstock used in the trade is H. virginiana. This species hails from North America and is the plant most used medicinally. It can be attractive in its own right and usually flowers in the late summer with its leaves on. These rootstocks come in bundles of 100 and I purchased them at a cost of £1.40 each from a wholesaler.
That was the easy bit, now for the method. I am a complete novice when it comes to grafting. I attended a one day workshop a year ago and managed to successfully graft my own apple tree but that is the sum total of my experience. Yet it is a fascinating and rewarding technique if practised. Fortunately, I have enlisted the help of a more experienced friend to help or at least show me the ropes.
There are as many methods of grafting as you can shake a stick at and lots of different tools to use. The standard bit of kit for most jobs is a sharp straight bladed knife and some grafting wax or sealing tape. The knife is used to make as clean and precise a cut as possible because any damage to the rootstock or scion will impair the union. The wax or tape is used to seal the wound and prevent infection.
You need to have some dexterity with the knife which is what I am most worried about. The next thing is to select the method. There are two widely practised methods. The first is the “whip and tongue” method where opposite wedge shapes are cut in the scion and rootstock and slotted into each other using a small “tongue” which just helps hold them together more firmly. The union should be close as most of a plants tissue is dead but on the outside of the stem just under the bark is an area of living tissue called the cambium layer. It is vital that these layers meet and fuse together for a successful union to take place. If they do not then the scion will not be able to take up water and nutrients and will just die.
The method that I will use however is chip-budding. The name is pretty self-explanatory. A bud (the chip) with an attached layer of cambium is cut away from the scion and a matching bud chip is cut from the rootstock. The two are then married up and bound with budding tape which seals the union and prevents damp causing fungus to spread.
The ideal time for this kind of operation is February so I will update you on my success or lack of it. Whatever the result it promises to be a rewarding experience!
In the Kitchen Garden
Whilst the weather is so wet it is better to stay off the soil as much as possible. Besides it being a miserable and messy job working on claggy soil, you are destroying the soil’s structure. Jobs have still got to be done, so when the opportunity arises get out and do them. This is mainly muck spreading and digging at this time of year.
I will be sowing sweet peas this month into pots, with bottom heat of 15 °C. This will give early sweet peas. You could also get going with other sowing of things such as parsley, broad beans and early cabbage.
Please note: images have been removed from this pages because some of them may have been used without permission.