The spring blooms are a joy and an inspiration after the often-dreary winter. Time spent now will pay big dividends for the new season. The focus for these months is on the four P’s preparation, purchasing, planting and pruning.
Any new beds should be prepared in April/May. Where drainage is not the best it is important to raise the beds – up to a foot if necessary. Raised beds are in fashion anyway and there are some nice surrounds available too. Put a dressing of slow acting fertiliser on existing your beds. It helps to develop nice fat buds for the new season. Rake up all fallen leaves and burn them as they can harbour spores that spread disease later on. Lightly aerate the soil to correct compaction of the soil from the winter rains. Attend to weeding.
In preparation for the spring, it is highly recommended that clean up sprays be applied in June. Note that you must not use lime sulphur and copper based sprays within 2 weeks of each other. Make sure of this when you plan your spray programme. Lime Sulphur at winter strength is 1 part to 15 parts of water. If you are troubled with white scale – then paint the lime sulphur mixture on to the canes with an old paintbrush.
Do check your pruning gear. I have found a fine keyhole saw to be invaluable in completely removing canes at the base of the bush. My other handy tool is the wire brush, which gets rid of scaly, knarled bark around the base of the bush and also on the top of the stem on standard roses.
It is a good idea to get your secateurs and loppers professionally sharpened from time to time. Ensure you have immunity to tetanus as the microbe that causes this condition typically lives in the soil and enters the body through cuts and wounds.
Perhaps you have ordered your bushes from a nursery or garden centre and you will be eagerly awaiting their arrival. If not most garden centres promote new roses early in June. The modem trend is for them to be growing in their black plastic planter bags. Keep them well watered until you get them planted. Choose your bushes carefully and try to get those that have 3 or 4 strong, undamaged canes.
Note the bushes have not been pruned but have been trimmed for ease of handling and transportation. Insist on buying high health bushes so that you avoid problems with virused bushes. Keep all your dockets and labels in case there are problems, whereby you want a refund or replacement bush. Look out for specials on sprays and fertilisers and shop around. Some good savings can be made. NitrophoskaBlue is a very good slow acting fertiliser in pelletised form.
Be careful about buying $3.99 roses from supermarketsand the like – you may get what you paid for and have to wait several years before the bush is mature.
Many bushes are sold with planting instructions and diagrams supplied by the propagator. This is one of the few chances you get to put nutrients underneath the bush, such as some nice compost and slow release fertiliser such as Nitrophoska Blue or Osmocote. Trim any damaged roots with sharp secateurs and water your plant in well to remove any air pockets. Give the bushes 1 metre of space away from other plants. Don’t forget to stamp the soil down firmly and come back again several days later to further firm the soil. In costal areas with a very acid soil you may need to add lime or dolomite to your beds.
There has been considerable discussion on methods of pruning, including the hedge clipper method, which is quick and doesn’t involve a lot of fuss. Many rosarians recommend pruning each bush as an individual, regardless of what you did to the two either side. Note that white and yellow roses often resent hard pruning. It is important to realise that climbers are pruned quite differently to bush roses. Whatever the plant, try to recognise old canes, new canes, basal shoots and suckers. Basal shoots are the lifeblood of the plant and are to be protected at all costs while suckers are loathed and need to be eliminated at the earliest opportunity. Suckers are coming from the under stock of a budded plant and take goodness away from the bush itself. Most people prune in July and even August.
Remember the text of the pruner should be “Let there be light” by clearing out the centre of the bush and any overcrowded growth. Most people remove any wood slimmer than a pencil.
Large pruning cuts – bigger than a 20-cent piece – can be sealed with a thin layer of petroleum jelly. Don’t forget a post prune spray of copper and oil to complete the job.
Extract from NZ Rosarian, June 1996