Clearing & Tidying
Posted By: Paul 08/12/2009 09:36:00
Clearing and tidying are the jobs of the moment and this week I am going to prune the blackcurrant bushes and raspberry canes.
The raspberries are the easiest to deal with as they are an autumn fruiting variety I will be cut them down to just above the soil level, but the blackcurrants are a little tricky to deal with. Blackcurrants fruit for the second years growth and will need pruning after their 3rd year, so if you cut the whole thing down this year, you'll have no blackcurrants next year. Selective pruning is the solution, and with blackcurrants they make it easy for us to do this as the shoots change colour each year as an indicator of age. To start pruning a bush in the first year trim a third of the bush away and leave the rest. In the second year you will see the new brown shoots which have appeared, and the remaining two thirds of old growth. Remove half of the old shoots and leave for another year. In the third year you will see the new brown shoots, and you will also see last years shoots have now turned black. The remaing shoots which now need removing should have a good algae growth on them giving them the appearence of being green. Remove the green shoots and leave for another year. From now on each year you come to prune the bushes you need to remove the green ones only. A nice simple way to deal with the pruning.
Whilst I'm on the subject of pruning a technique called nick and notch pruning can be very useful in many situations. The theory behind it is to stop a shoot from growing so vigorusly and encourage it to bush out more with some sideshoots. For example on an apple tree you may have pruned it last year and now it has a large number of 'water' shoots growing straight up. Some of the shoots might be needed whilst others can be pruned back by half. To make one of these shoots bush out you will need to trick the tree into starting the side shoots growing and slow down it's upward growth. The top most bud on the shoot is known as the Apical bud, and whilst it is growing upwards it produces Auxin a 'plant hormone' (plants don't have hormones, it's just a name) which flows down the shoot and through the plant to the roots. On it's way down through the shoot it travels past each bud in turn and keeps them in a dormant state. If you cut the apical bud off the shoot the next bud down will now become the apical bud as it is no longer being kept in a dormant state by the auxin from above. Rather than cutting off the apical bud if you 'nick' the stem immidiatly below it this reduces the rate of growth of the top bud. Then find a couple of buds along the shoot you wish to grow outwards and you notch the stem immediatly above the bud, see picture. This stops the flow of auxing to the bud and it now thinks it is the apical bud. Remove any unwanted buds between the true apical and the two false apical buds. The weakend apical bud can be cut off later when the shoots have grown. This technique can be used in many situations and on many plants. For example rather than cutting a rose right back to encourge new growth you can notch the stem above the bud you wish to grow from and still enjoy the remaing plant whilst you wait for it to grow.