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TECHNIQUES & TOOLS |
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How to Plant a Tree |
| Planting Techniques - Some Common Mistakes | |
| Sowing from Seed | |
| Gardening in Containers | |
| A Basic Pruning Guide | |
| Rose Planting | |
| Rose Pruning | |
Choosing a tree carefully and planting
it skilfully will help to ensure that it has a long, healthy life as a major focal point
in your garden.
Size
Bigger does not necessarily mean better when it comes to trees. When advanced trees are transplanted, they may lose up to 90% of their functioning roots. It is little wonder that it can often take a long time for the tree to start growing again - sometimes years. Smaller plants are less likely to suffer such a high degree of transplant shock. They are easier to handle, and if they have been propagated well in suitable containers, they can go ahead very quickly and develop into strong, healthy trees with good root systems. Within five years there may be little difference in size between a small plant and an advanced specimen. In fact the small tree may well have outstripped the advanced one. However, sometimes we have to choose larger plants for aesthetic reasons or simply for visibility so that they are not so easily damaged by mowing, kids, etc.
Pruning
In the past, the thinking was that pruning a tree at transplanting time made it easier for the plant to cope with the loss of so many of its roots. Recent horticultural research has indicated that there is no scientific basis for this idea and in fact, the loss of leaves reduces the plant’s ability to photosynthesise and may make it more difficult for it to develop the vital new roots required.
The Planting Hole
The most important thing is to dig a really good planting hole. Bad holes are too narrow, too deep (or both), round and smooth sided. A good planting hole is dish-shaped, much wider than the width of the plant’s root ball - at least three times as wide and more if the surrounding soil is compacted. It should be no deeper than the depth of the existing rootball. You may loosen the soil below with a fork, but don’t dig it out. Don’t put compost or manure in the bottom of the planting hole - anaerobic gases may be produced which will harm the roots of the plant. Do not add fertiliser to the bottom of the planting hole either. Roughen up the sides of the hole so that roots can easily enter the surrounding soil. Smooth sides can resemble the sides of a pot and can cause root circling which can severely limit the growth of the tree.
Planting the Tree
The most important thing to remember is to treat the roots of the tree with great care. Don’t leave the pot standing in the hot sun while you dig the hole. Don’t lift trees by their trunks. Don’t pull at roots to "tease them out"! If you find there are roots circling around in the pot, take a sharp knife and score to about 5mm deep down the sides of the root ball in three different places. (Reject any tree that has doubled back roots near the trunk. This is a sign of poor propagation techniques and the tree will almost invariably be short-lived or snap off at the base at some stage.)
Place the tree in the planting hole. Be sure that the top of the potting medium is not below the level of the surrounding soil. If you wish to add organic material to the backfill only add a small amount of well-composted material (about 5% of the volume) and mix it in well with the site soil before back filling. Make sure there are no air pockets, but do NOT do this by stamping on the soil which will cause compaction. It is very important that the top of the potting medium is not covered by the back fill.
Watering
Diligent watering during the establishment period of the tree is the single most important success factor. With limited roots, the tree cannot be allowed to dry out. This applies to all species, including drought resistant ones. They will be drought resistant only after their roots are well-established. Initially they need watering. This TLC should continue throughout the first year. There is no credence in the idea that you can "toughen up" a plant by treating it badly - you will simply end up with a plant of lesser quality (or no plant at all). Watering should consist of deep soaking , not just light sprinkling. You can build up a small ridge or berm just beyond the root ball to encourage moisture penetration if you wish. Many trees will not cope with having large amounts of soil piled up over their root zone, so construct any garden beds, rockeries etc that are to be below the canopy of the tree (or near by) before you plant it.
Fertilising
Do not fertilise a tree at planting time. Instead, water it well until you see signs of shoot growth. Then you can fertilise. A slow release fertilise is a good choice. Remember to place fertiliser away from the trunk - put it in the area where the new roots will be making their way into the site soil. Remember that the most important roots are in the top 15cm of the soil where there is adequate oxygen supply.
Mulching
Mulch is important for vital moisture retention and to reduce weed competition. Don’t apply mulch too thickly (75mm or 3 inches is the maximum for most mulches). If the mulch hasn’t been composted, then the fertiliser you use should be high in nitrogen. (Nitrogen is consumed by micro-organisms as they decompose organic material. This is called nitrogen draw-down) Keep mulch well away from the trunk of the tree to prevent fungal attack such as collar rot.
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Taking care when you are planting out your plants can make a huge difference to their chances of doing well.
Here are some common mistakes that gardeners make:
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Propagating plants from seed is a very rewarding experience and an
inexpensive way to produce bedding plants for massed displays. It is important to remember
though, that plants vary enormously in their requirements for germination. What works well
with one type of seed may not work at all with another.
Plants have evolved a whole raft of ways of achieving a reproductive advantage so that their seed has the best chance to germinate and grow. Many dry climate plants, for example, have an extremely hard seed coat that will only soften sufficiently to allow water to enter and germination to occur when there is sufficient rain to sustain the seedling - a passing shower would be of no use in such a climate. These seeds often require soaking or scarifying before planting e.g. Albizia. There are other seeds, however, that will be damaged by soaking - peas are a good example.
Some seeds need to pass through the digestive system of an animal before they will germinate e.g. Eremophila. This process can be very hard to replicate in a nursery! Some seeds have a period of dormancy during which the seed continues to develop and germination will not be successful during this time e.g. Clematis.
Seeds of tropical plants are frequently recalcitrant. This means that there is no period of dormancy at all - as soon as the fruit falls from the tree it is ready to germinate. This is an understandable response in the productive, warm, moist conditions of the tropics where conditions for growth are always suitable and competition between plants is high. For gardeners this is important, as only fresh seed will germinate.
Some seeds require light to germinate, some need darkness and for others it doesn’t matter. Some seeds need to be exposed to cold for a period before they will germinate. Many seeds respond to plant-derived smoke. Some plants need to be grown in situ i.e. where they are to grow; while others are best grown in seed beds, cells or punnets and transplanted later. Always read the directions on the seed packets carefully - it can make the difference between success or failure.
Most commonly, seeds are sown in the following way. A light, easily-draining medium is chosen - there are a number of seed-raising mixes available commercially. This material needs to allow free access of oxygen while maintaining sufficient moisture for the germinating seed. Water is essential, and once seeds have begun to germinate, if they are allowed to dry out they will die.
Once the shoot emerges from the medium, the plant requires sufficient light levels to grow well. Seeds do not need fertiliser to germinate but once the root has grown, the plant will then benefit from the application of fertiliser. Once the seedling has developed a couple of true leaves, it should be "pricked out" or transplanted to a larger pot. Careless "pricking out" can lead to poor quality plants. If the root of the seedling is doubled back when it is potted on, the plant may develop what is termed "J roots" and will be fundamentally weakened. Always make a hole sufficiently deep to accommodate the root, or if it is too long, nip it off rather than bend it back over itself.
Cells prevent many of the problems associated with "pricking out". These are soft plastic containers with individual cells like an egg carton. The containers fit neatly into punnet trays. A seed is sown in each cell. When the seedlings are ready for transplanting, the whole root system can be squeezed out gently and planted with minimal disturbance.
Once the seedlings are established they are ready to be planted out into the garden or into larger pots. For the majority of plants, this process will lead to a higher level of success that direct planting of seed, which is often carried off by ants and other creatures, or washed away.
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There is a whole range of container types to choose from and the choice depends both on your purpose and your budget. Terracotta looks classy and the pots eventually develop their own aged patina which adds character. Evaporation from the clay pot keeps the roots cool and the atmosphere around the plants moist. However the pots must be watered religiously because they can dry out very quickly in summer. If you are forgetful, very busy or don't have a watering system, then it might be wiser to choose some of the plastic terracotta look-alike pots - perhaps some with a self-watering capability. (Remember that self-watering does not equate to no-watering. You just don't have to remember quite so often!) Glazed pots keep moisture in more effectively than unglazed pots. However unglazed terracotta pots may be just the thing for plants that require excellent drainage - many of the Western Australian plants spring immediately to mind. Alternatively, it is easy to grow bog plants in containers without drainage holes - cut down barrels are great for this purpose.
Hanging baskets provide the opportunity to increase the scope of a multi-level garden. Open baskets lined with coconut fibre, bark, or moss liners are the most popular because they blend in well with vegetation - pots and baskets should themselves be relatively inconspicuous so that they do not draw attention away from the plants and create disharmony. A major problem with hanging baskets is that, because they are so exposed to the air, they dry out very quickly. Remember that wind, not sun, is the major drying agent. Try not to hang baskets where they are exposed to a constant air flow. Site the pots so that they are easily reached for watering, or they will soon look tatty.
The list of plants that can be grown in pots is endless. It includes elegant topiary specimens, dwarf fruit trees, a huge range of perennials, annuals such as petunias, primulas and pansies, bonsai, cacti, orchids, palms, ferns, creepers, bulbs, water plants, strawberries, herbs and, of course, a whole range of wonderful vegetables that have been specifically developed for growing in pots.
An important consideration when container gardening is what kind of potting medium you use. When you consider the cost of your plants compared to the cost of potting mix, it is clear that buying cheap medium is false economy. Good quality potting mixes are prepared scientifically and give your plants the best opportunity to thrive. Look for the Australian Standards logo on the pack. Regular watering and fertilising are essential for healthy container gardens. Slow release fertilisers are particularly useful.
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It is difficult to give general pruning advice. There is no guide that can tell you what you need to know about pruning every plant in your garden. There are so many variables to be taken into consideration. What type of plant it is, when it flowers, whether it flowers on new or old wood, when the growing season is, how responsive it is to pruning and whether it can regenerate from old wood are just some of the questions involved. There are some general principles, but if in doubt, tread carefully. Do some research at the library, ask your nurseryperson, or do some careful and inconspicuous experimentation. Do avoid the "raze-it-to-the-ground-and-hope-for-the-best mentality" so beloved of certain garden nazis. Not leaving them alone with the secateurs or a pruning saw is rule No.1!
General Guidelines
Use sharp tools and disinfect them by cleaning with methylated spirits.
Ragged edges are an invitation to disease to enter your plants.
Make
clean cuts that slope away from buds. Cut close to and parallel to existing
branches, but not flush with them.
First cut the bark below when pruning a large branch to prevent tearing
of the bark.
Use the plant's natural habit as a guide. If it is slow-growing, compact
and well-shaped, then only light pruning to tidy it up is necessary. If it
is fast-growing, then more frequent pinching-out or pruning may be
necessary.
Many
flowering shrubs (including natives) are pruned back after flowering.
Depending on the species, this might be as simple as removing dead flowers.
Some species respond better to more severe pruning. Err on the side of
caution. Deciduous shrubs that flower in summer and autumn are generally
pruned in winter, while those that flower in spring are generally pruned
immediately after flowering.
Prune roses in late winter. Remove any dead wood and spindly branches.
Cut back stems to just above healthy outward-facing buds and cut on an angle
sloping down and away from the bud.
Before pruning fruit trees find out what kind of wood produces the
fruit, otherwise you may be pruning off fruiting branches.
Conifers require little or no pruning. Those used for hedges e.g. Cupressus
macrocarpa, should not be pruned to old wood, but clipped lightly and
regularly. (If you have a cypress hedge that has been butchered, it may
regenerate if cut completely to the ground, but it won't regenerate from old
wood.)
If you are planting close to a path or driveway, choose a plant that
responds well to heavy pruning, or allow enough room so that the plant can
maintain its natural shape.
Winter is the season for planting roses. On the whole, roses are
quite robust and durable plants. Take a little care at planting time and your rose bushes
will give you years of pleasure.
Position
Roses need plenty of sun - six hours a day to really thrive - so select a sunny spot. If
you have a choice between morning sun and afternoon sun, choose the spot that is sunny in
the morning. The position also needs to be well-drained.
Soil
Roses like soils that are a little acid (6.5 is best) so a pH test is a good idea. (You
can buy an easy-to-use soil testing kit from the Global Garden Shop.)
Roses prefer a rich loam to which compost, cow manure or other organic matter has been added and do well in areas where there is a clay subsoil.
Types of Plants
Roses can be bought as container plants in any season. Buying roses this way means you are
able to purchase the plant in bloom so that you know exactly what you are getting. In
winter there are many roses available as bare-rooted plants. These are less expensive and
much easier to manage.
Planting
Soak bare-rooted roses in water for an hour or so before planting. Dig a hole that is more
than adequate to fit the roots in comfortably. Make a mound of soil in the bottom of the
hole and spread the roots over the sides. Half fill the hole with soil and then water well
and let the water drain away. Fill in the rest of the hole making sure that the final soil
level is a few centimetres below the bud union. (This is the knotty, woody bit of stem
between the roots and the canes.) Water the rose well. Don't fertilise at planting time.
Mulch
Roses don't like competing with other plants, so it is important to keep grass and weeds
under control. An organic mulch will help with weed control, conserve moisture and add a
little acidity to the soil.
Companion Plants
Because roses are not very sociable they are often planted well-spaced in beds on their
own. While this may ensure the best blooms and minimise disease, rose beds can look very
stark. A good trick is to surround the rose bed with a low growing hedge that disguises
the lower, least attractive parts of the shrubs and lets us enjoy the sight of the
wonderful blooms above.
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Rose pruning can be quite a complicated business because of the wide range of roses and their varying requirements. Many nurseries offer rose pruning demonstrations and gardening courses often cover this in detail. Here, however, we are offering a simple general guide.
July is the time to prune most roses. Exceptions are the winter flowering roses such as 'Lorraine Lee' and 'Nancy Haywood' and these are best pruned in March. Roses which flower once a year on the previous season's growth should be pruned after flowering. Species and old roses do not require much pruning apart from removal of dead and untidy branches. Before pruning, ensure that the secateurs are clean and sharp. A pruning saw may be needed for removing hard old wood. Protect yourself well from the thorns as punctures from rose thorns are notorious for becoming infected.
The main objective is to remove old and unproductive wood from the plant. These branches usually bear only thin, scraggly growth. Cut these out at ground level or where they join the main stem. Some canes will be useless for part of their length so can be pruned back to just above a healthy branch. Also pruning keeps the bush to a manageable size. Making pruning cuts at the correct place and at the right angle gives the bush its best chance to avoid disease and to develop healthy new growth.
Stems should be cut only just (about 6mm) above a healthy, out-facing stem bud. (These form at places where the leaves have joined the stem.) Cut the stem at a slight angle with the slope draining away from the bud.
You may choose to cut the bush back by a quarter or a third, or whatever amount gives it a good shape and retains as much of the foliage as possible. Preserve the lush pink water shoots - these provide new flowering canes and can be trimmed next season if necessary.
This main pruning is done in winter (late winter in really cold areas), but dead-heading and light pruning through the year after flowering, will keep your rose bushes blooming well.
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