THE BONSAI YEAR

The details here are a general guide, and it will depend on location and climate as to when some actions are done. For example in the far south re potting can be as much as four weeks ahead of the rest of the country, and Scotland and the north even later.

There are a number of products available for re potting including Kanuma which is mainly for Satsuki. Kiryu which is a grit. Kyodama is a British product. Most bonsai nurseries have a basic mix for sale.

You must watch your trees to see when things can be done and use this article as a guide only.

Trees are re potted every two years if in training. Old trees anywhere from 3 to 5 years.

January

Fertiliser

Do not fertilise deciduous conifers can have fertiliser.

Pruning

Do not prune.

Trimming

Deciduous trees probably have no leaves to trim. Conifers should not be trimmed.

Re potting

Depending on location and weather conditions it may be possible to start re potting late in the month.

Insects / Pests

These should have already have been eliminated.

Wiring

Leave it alone.

Propagation

Cuttings. Plan your seed-sowing programme. Probably the best overall results are obtained by gathering fresh seeds now and sowing for germination next spring. Hard coated seeds such as Hawthorn may require up to 18 months stratification. If you have enough, divide seeds into two batches, one for immediate sowing, and the other for stratification.

General

Inspect periodically, especially when snow may start to fall. The greatest danger is drought due to a snow-covered pot drying out. Perhaps the best antidote is to put the pot in the bath and spray with cold water until the snow is dispersed. The temperature is kept low, but the water will get to the soil eventually. Keep in a cool greenhouse or shed, or put outside in the day in sunshine if possible. If you ordered soils and other supplies, start getting it ready.

February

Watering

In dry weather, check daily and water if needed, but not if there is threat of frost.. In wet weather, let the rain do it for you, but water if it has not rained for three days if needed. Water in the morning.

Re potting

Re potting can start mid month onwards.. Make sure you have plenty of dry sifted soil ingredients or compost ready for the Spring and store under cover. If you have not already done so, make a list of the trees you intend to report. To decide if this is needed, turn the root ball out of the container carefully and examine it – if it is a tight network of roots then it needs root pruning and re potting. This is done to keep the roots active and growing in fresh new soil. Check that you have all reserve pots cleaned ready for potting on. Prepare your potting mix this month. Akadama is a good medium, or for a cheaper option Basic Mix two parts horticultural grit and three parts garden loam.

Fertiliser

Hardly necessary yet although pines may be given a little fertiliser.

Pruning/trimming

It is not advisable to remove any unwanted branches or twigs yet. Those that you remove may be alive; those that you leave may turn out to be dead.

Insects / Pests

Still too early to worry, except for Citrus, which may have brown scale insects still undetected. Pick them off by hand.

Wiring

Not yet.

Propagation

Prepare seed pans for sowing. Soak slow-starting seeds and sow under glass. A good month to start striking Willow cuttings. Place in water and keep indoors near a window. Salix babylonica, S.purpurea and varieties of Golden Willows S.Vitellina aurea and S.V.A. Pendula are all worth trying.

General

In cold weather keep tender plants in an unheated greenhouse or shed. Check every day and water when needed. Check all pots for cracks or frost damage.

March

Watering

In dry weather, check daily, and water if needed.  In wet weather, let the rain do it for you, but check that water is getting to soil under canopy. Water in the morning. Spray any re potted trees daily.

Re potting

Have you followed the February instruction? Make sure now and remedy any deficiencies. Watch the buds of trees listed for re potting. Mild weather may bring them on. As soon as they start to move, re pot quickly and shelter from the wind.

Fertiliser

Hardly necessary yet, apart from Azaleas. For trees not to be re potted, but where plenty of future growth is desired, a little fertiliser can be given. Do not fertilise any newly re potted trees for about four weeks.

Pruning

Unwanted branches may be removed only if the retained branches are clearly alive with buds on the move. But exercise restraint. Prune back to a suitable living bud pointing in the right direction. Seal large wounds with sealing compound.

Trimming

Where too much growth is expected, and buds are well advanced, removal of unwanted future twigs may be anticipated by pinching out buds now. Where bushiness is desired, terminal buds may be pinched out if they are adequately supported by numerous lower buds. Do not overdo pinching.

Insects / Pests

Still too early to worry, except for Citrus, which may have brown scale insects still undetected. Pick them off by hand.

Wiring

Not yet. Remove any existing wire that may cut into the bark.

Propagation

Sow any seeds you left out last month. Suggestions for March sowing are Mauie’s dwarf Quince, Cedars, Pines, Crab, Punica granatum Nana, Cypress, Sophora japonica. Take softwood cuttings when buds are well on the move.

General

Check stock of insecticides, fertilizers and wire. Inspect unopened buds for signs of opening. Wash down all storage shelves, benches and outsides of all pots. Glazed pots of Japanese origin can be cleaned by rubbing down with soapy water,. Examine apparently dead trees, but do not discard such casualties yet. Add new top soil where required to trees not being re potted. Many may require this after the winter rains. In others, the top soil may look sour; remove this and replace with fresh compost.

April

Watering

Check and water every day if needed, sparingly for older trees, more for your trees where growth is wanted. Spray re potted trees daily.

Re potting

Complete all Re potting of deciduous continue with conifers.

Fertiliser

Do not fertilise trees re potted this month. Feed sparingly any trees re potted more than four weeks ago. Feed flowering trees, which have not been re potted.

Pruning

Unwanted branches may be removed only if the retained branches are clearly alive with buds on the move. But exercise restraint. Prune back to a suitable living bud pointing in the right direction. Seal large wounds with sealing compound. You can be bolder in April if the buds are breaking.

Trimming

Where too much growth is expected, and buds are well advanced, removal of unwanted future twigs may be anticipated by pinching out buds now. Where bushiness is desired, terminal buds may be pinched out if they are adequately supported by numerous lower buds. Do not overdo pinching. In April pinching can be resorted to more boldly.

Insects / Pests

Watch for Red Spider and White Scale. Spray with insecticide at appropriate strength. For Wireworm / Earthworm spray with Lindex at the normal concentration.

Wiring

Not yet. Have you removed all dangerous existing wiring?

Propagation

Take cuttings of late starters. Pot on last year’s seedlings.

General

Remove weeds. Plant moss. Inspect unopened buds for signs of opening. Be ready to give protection against night frosts to trees with newly opened leaves. Consider discarding winter casualties. If flowering bonsai are brought indoors for display they should be kept away from any source of heat and should not be kept indoors for more than a couple of days at a time.

May

Watering

Check every day and water as needed, sparingly for older trees, more for your trees where growth is wanted. Spray re potted trees daily. On warm days water twice daily any trees on which growth is to be encouraged.

Re potting

It is almost too late to re pot  so do early and do it quickly if you must.

Fertiliser

Begin with liquid once a fortnight. Remember to adhere strictly to the manufacturers instructions. Use less, rather than more in the water. Generous for flowering trees and for deciduous trees that have been leaf cut.

Pruning

Young trees under training – remove any remaining unwanted branches. Older trees – check that the wounds where any branches have been removed are carved and shaped to permit the callous to g

Keep a constant check to pinch unwanted buds and new shoots. Leaf-cut deciduous trees if you wish to increase ramification.

Insects / Pests

Watch for Red Spider, Aphids, Ants, Mealy Bugs. Spray. Cut off infected leaves of deciduous trees and burn. Watch for mildew.

Wiring

Wire as needed on conifers avoid wiring deciduous.

Propagation

Conifer cuttings.

General

Remove weeds. Put sun-sensitive trees such as Elms and Zelcovas into half shade, but still ready with frost protection for newly opened trees. Inspect for unopened buds for signs of opening.

June

This is probably the best month of the year for seeing your bonsai at their best. They will have beautiful new growth and lovely colours. Try to find time to sit back and enjoy them!

Watering

Check every day and water morning and evening if needed.

Re potting

Too late for potting in new soil, which would disturb roots, but you can pot on if you are careful to leave the old soil ball intact. The exception is Satsuki Azaleas, re pot once flowering is finished.

Fertiliser

Fertilising can continue throughout June.

Pruning

Young trees under training – remove any remaining unwanted branches. Older trees – check that the wounds where any branches have been removed are carved and shaped to permit the callous to grow over them. Trees that are very healthy may be leaf-pruned this month.

Trimming

Keep a constant check to pinch unwanted buds and new shoots. Leaf-cut deciduous trees if you wish to increase ramification. Check daily if possible.

Insects / Pests

Try to check every day. Watch for Red Spider, Aphids, Ants, Mealy Bugs. Spray. Cut off infected leaves of deciduous trees and burn. Watch for mildrew.

Wiring

Continue as needed.

Propagation

If this season’s seedlings are thriving, pot on into small training pots.

General

Remove weeds, especially Liverwort if it is rampant. Keep sun-sensitive tree

July

Watering

Water every day, except when appreciable rain has fallen. Be generous to trees planted in shallow pots, trees having a lot of moss in the pot, and trees subjected to a drying wind.

Re potting

Do not repot. If a pot is broken or the soil is partially washed away by heavy rain, disturbed by animals or accidents, pack the soil ball into a new pot without disturbing the roots.

Fertiliser

. Little and often is better than large dollops. Reduce nitrogen for trees such as maples and zelcovas in order to ensure best autumn colour.

Pruning

Pruning can still be carried out if really necessary, but do not leaf prune in July.

Trimming

Growth is still fairly rapid in many trees. Maples and elms must be constantly trimmed. Picea and Junipers may still need their new needles shortened by pinching. Check each tree daily if possible. Remove dead brown needles from conifers.

Insects / Pests

Try to check every day. Cut off infected leaves. Spray.

Wiring

Conifers can still be wired if needed.

Propagation

Cuttings can always be taken.

General

Remove weeds, especially Liverwort. Keep sun-sensitive trees in half shade – Acers, Elms, Japonicas and any that show signs of leaf scorch.

August

Watering

Water every day, except when appreciable rain has fallen. Be generous to trees planted in shallow pots, trees having a lot of moss in the pot, and trees subjected to a drying wind.

Re potting

Do not repot. If a pot is broken or the soil is partially washed away by heavy rain, disturbed by animals or accidents, pack the soil ball into a new pot without disturbing the roots.

Fertiliser

Begin to taper off , and change to low nitrogen... Always soak soil before fertilising. Pines will need less now. Sequestrine can be added when watering Azaleas and Pines.

Pruning

Summer pruning can continue.

Trimming

Little is now needed, as growth will have slowed down. Remove dead, brown needles from conifers.

roots.

Insects / Pests

Check every day. Cut off infected leaves. Spray as necessary.

Wiring

Conifers only.

Propagation

Take semi-hardwood cuttings for rooting under glass. This is a good month for any cuttings.

General

Keep down weeds

. September

Watering

Check every day and water as needed.

Re potting

Those who favour Autumn re potting for conifers could start late this month.

Fertiliser

Very sparingly using fertilizers containing mainly potash and phosphorous and very little nitrogen.

Pruning

Can be done if needed.

Trimming

There may be a pre-Autumn burst of growth requiring light trimming.

Insects / Pests

Check every day. Cut off infected leaves. Spray as necessary.

Wiring

Test wired branches gingerly to see if they have taken the required permanent set. If so, remove wire. Wire can be replaced if needed.

Propagation

Take semi-hardwood and hardwood cuttings.

General

Remove weeds and any moss not in top condition. Protect moss from birds, which at this time are searching for insects. Remove dead leaves and tidy up pots. By now you may have found some wild trees for lifting. When possible, leave them for lifting next spring, but if this is not practicable lift them now.

October

Watering

Water can be cut back but trees still need as much light as possible.

Re potting

Those who favour Autumn re potting for conifers could start this month.

Reduce the amount but keep up with conifers..

Pruning

Do not prune.

Trimming

Deciduous trees probably have no leaves to trim. Conifers should not be trimmed.

Insects / Pests

Check every day. Cut off infected leaves. Spray as necessary. In October there will not be as many pests still active.

Wiring

Do not wire. Test wired branches gingerly to see if they have taken the required permanent set. If so, remove wire. Do not bend or re-wire.

Propagation

Cuttings as for September. Plan your seed-sowing programme. Probably the best overall results are obtained by gathering fresh seeds now and sowing for germination next Spring. Hard coated seeds such as Hawthorn may require up to 18 months stratification. If you have enough, divide seeds into two batches – one for immediate sowing and the other for stratification.

General

As for September. If you contemplate plunging any pots get the ground ready now. If you are going to winter any pots inside clear a suitable space for them in a cool greenhouse or shed. Most trees can stay outside but tender or exotic ones may need protection.

November

Watering

Water sparingly once a day if it has not rained. Most trees will be dormant now. Use soil pesticide to eliminate leather-jackets and other pests.

Fertiliser

Do not fertilise deciduous but keep up with conifers..

Pruning

Do not prune.

Trimming

Deciduous trees probably have no leaves to trim. Conifers should not be trimmed.

Insects / Pests

Check all over branches and twigs and pick off any galls, blisters, scale insects and other infestations that may think they are settled in their winter quarters. Water thoroughly all trees, soil and pots with a mild disinfectant fungicide.

Wiring

Do not wire. Test wired branches gingerly to see if they have taken the required permanent set. If so, remove wire. Do not bend or re-wire.

Propagation

Cuttings. You can pot on last Springs seedlings if you do not disturb the root ball. This will save time next Spring, when you are bound to be busy.

General

Review the trees that are to be given shelter – Citrus, Azaleas, Conifers with spreading branches. Plunge or protect with straw. Gravel or cinders can be used to plunge. Check all pots to ensure drainage holes are clear. Frosts are more dangerous to pots than trees.

December

Watering

Water reduced to absolute minimum – slightly damp but not wet as frost does less damage to drier trees. Water in the morning, not the evening.

Fertiliser

Just once for conifers..

Pruning

No pruning.

Trimming

Deciduous trees probably have no leaves to trim. Conifers should not be trimmed.

Insects / Pests

Check all over branches and twigs and pick off any galls, blisters, scale insects and other infestations that may think they are settled in their winter quarters. Water thoroughly all trees, soil and pots with a mild disinfectant fungicide.

Wiring

Leave it alone.

Propagation

Cuttings. You can pot on last Springs seedlings if you do not disturb the root ball. This will save time next Spring, when you are bound to be busy.

General

Inspect periodically. If a pot is cracked, tie it up with string as a temporary measure. It is not too early to check your supplies and order as necessary. Remove any dead under-planting, which can shelter pests.