The Bonsai Year – North Island

New Zealand’s climate ranges from the Winterless North, through the warm and wet Waikato and alpine regions in the west of Canterbury to the cool South, with the next stop being Antarctica

This provides for a wide range of species being grown as bonsai which are more suited to one area than another.
It’s no good trying to grow Larches or Southern Beech North of Auckland and some of the more delicate species do not like the colder climate in Otago.

Here we have put together a few guidelines on what you can do with your trees at various times of the year.

THIS IS A ROUGH GUIDE ONLY – Your area may well be in front or behind these times.

The North Island tips are based on the Waikato region, The South Island tips on the South Canterbury region

January

Water! Water! Water!

December/January is the time to keep a careful eye on the water needs of your trees. Try to water in the mornings before lunch as watering at night leaves the roots of the trees sitting in water when they should be taking up air not water.

Shade from midday is a good idea for most species used in the art of bonsai. Pines and cedars are the main exceptions to this, as they love full sun even in the shallowest of bonsai pots.

This is the time to trim those shaggy maples you have been allowing to grow over spring. Pines can also be pruned once the needles have fully developed.

It is also a better time of year to wire trees that need shaping, as the wire won’t cut in so quickly, and trees often set in the new shape quicker.

Unless you are really keen, there is little point in feeding in December/January, as the flush of spring growth has passed.

When you are going on holiday get someone to check on your trees, even if you have an automatic watering system, as things can sometimes go wrong like blocked water jets, pots that have fallen over, or flat batteries in the timer. Check that the jets of your watering system are not blocked even if you are not going away.

February

February is still the time to keep a careful eye on the water needs of your bonsai.

If you usually water with the hose each day, watering occasionally by dunking the tree in a bucket or deep dish is a very good idea. Submerge the bonsai so the water is well above the soil level and leave it in the water till all the bubbles stop.

At this time of year many local councils have high chemical levels in the water supply, so allow the water to run out of the hose for a minute or two before watering your trees. Try also to water in the mornings before lunch, as watering at night leaves the roots of the trees sitting in water when they need to be absorbing air.

February is another time to repot species of trees that enjoy the heat like Pohutukawa, Figs, Jade Trees, and other tropical and semi tropical species.

This is now the time to do summer pruning of the extension growth on most species of bonsai (all those shaggy maples you have managed to resist chopping back for soooo long). Also continue trimming ‘Southern’ Trees like Chinese Elms, Zelkova, and Trident Maples back to 3 or 4 branchlets constantly. Pines can be pruned by removing the unwanted growth (which has developed from the candles produced in spring) once the needles are fully developed.

February is also the time to return to feeding your trees. Liquid or solid, organic or pure chemical. Your choice!

March

Re-potting of most species of tree can continue into March as there will be a second growth spurt in autumn allowing the trees to recover before winter. Remember to put newly re-potted trees in a position where they get shade from noon and shelter from strong winds.

As the temperature drops by the end of March, you can begin to wire trees that need shaping. You will need to watch that the wire doesn’t cut in though.

Feed your trees now. A one off top dressing of your favourite general purpose fertiliser will suffice, if you are not up to liquid feeding weekly (make sure you water well after applying Blood and Bone or Fish Meal to prevent yours, or your neighbour’s cat attempting to lick it all off). If you can find a low nitrogen feed start using that as the trees need higher Potassium and Phosphorus levels for winter protection.

April

Feed any trees that still have leaves, but don’t bother if they have lost their leaves as they are already dormant and will not use the food.

It is time to remove the old needles from Pines and Cedars.

Wiring can be done now as the flush of autumn growth is mostly over in the Waikato region.

It pays to put the cover on frost tender plants. Frosts can be devastating.

May

This is the time to do autumn pruning of deciduous trees once the leaves have fallen to improve their shape.

May is also clean up time after the leaves have fallen, as even bonsai can suffer re-infestation of insects and diseases if leaf litter is left on the surface of the soil or on the shelves.

A clean up spray for lichen and insects is a good idea this time of year too, if you are into spraying preventatively.

May is still a good time to wire trees to improve their shape.

June

Winter is here. Frosts can cause bonsai to dry out, so keep an eye on the water needs of your trees.

There is still time to remove the old needles from Pines and Cedars if you have not already done so.

Autumn/Winter pruning of deciduous trees can be done now, and early flowering trees such as Camellias can be pruned once they finish flowering.

Wiring can be done now as the trees will have plenty of time to set in place before spring growth causes swelling, and the wire to cut in.

June is clean up time. Remove moss at the base of your bonsai tree’s trunks. Using an old tooth brush while the moss is wet makes it quite easy. Spray your trees now if you’re into it. Spray for insects and lichen this time of year. There is still a need to clean away leaf litter from the surface of the soil, on the shelves around the trees and under the shelves too.

July

Time to prepare for springs re-potting season. Buy in, or gather the ingredients you need if you make your own mix, and make sure you have enough wire, string, and mesh to cover pot drainage holes. Make sure you can get to your selection of bonsai pots, in-case you decide to change a trees pot, and clear space in ‘The Shed’ to work, as it is bound to rain.

July is the time to lift any trees that have been growing-on in open ground or in the garden, and a good time to collect trees from the wild (with permission from the land owner of course).

In the Waikato region July is the time to re-pot Cedars. The timing is critical for the safest re-potting of Cedars. You have the time between when the buds on the top of the tree and at the tips of the branches start to swell, till when the buds show a little green only. A matter of only days in some trees so watch your Cedars closely. Once the buds on Cedars open it is too late, and re-potting could result in a lot of die-back or even the loss of the tree completely.

August

As the days lengthen there is still time to re-pot most things in the Waikato Region (other than cedars as it is probably too late for them).

Pines and conifers and some natives like Totara and Kahikatea are best re-potted in August.

Deciduous trees are best re-potted as the buds start to swell and can be safely re-potted up until the leaves unfold, which can vary drastically in the Waikato from late August to October.

September

Watch for slugs and snails as they will demolish the new leaves on deciduous trees very quickly.

Flowering trees like Camellias, Azaleas, and Wisteria can be re-potted in September or as soon as they finish flowering.

If you are not re-potting certain trees this year, they need nutrient or feed. There are heaps of options for fertiliser but whatever you choose, only use at the strength recommended, as more is not better in this case.

Check any trees that are wired, as the wire may need to be removed if it is cutting in. The trees may need to be re-wired if the branches are not set in place.

October

Check the wire on any of your trees regularly at this time of year as wire can cut into the bark in a matter of days with some fast growing species.

Watering is now necessary don’t just rely on rain.

Slugs and snails are out in force now. If you have pets then use ‘Quash’ Slug Bait sprinkled around the top of the pots of larger trees or on the shelf around the pot. There is an antidote for that brand if your pet is silly enough to eat any of the pellets. Others may use more ‘Green’ suggestions. You can go out at night with a torch and squash the slugs and snails but it’s a bit of a job when you have a large collection.

This is the time when all sucking insects are doing damage so spraying is also a good idea. Pyrethrum is a good general insect spray but once again there are lots of sprays on the market for different insects. Use only as directed on the packet.

Apply nutrient (or feed) your bonsai this time of year. Use fertiliser only according to the directions on the packet or bottle. More is not better. Do not fertilise bonsai that have been re-potted in the last 6 weeks or bonsai that are sick (unless you are sure the tree is sick because it is starving).

Trim ‘Southern’ trees like Chinese Elms, Zelkova, Trident Maples, back to 3 or 4 leaves constantly now. Leave trimming ‘Northern’ trees like other types of Maples, Beeches, Oaks, Hornbeams, and Pines till Christmas.

Flowering trees like Camellias, Azaleas, and Wisteria can be re-potted as soon as they finish flowering.

November

It is not too late to re-pot some hardy trees like Junipers, Chinese Elms, and of course Privets now. Just remember to shelter them from strong winds and too much sun.

Take care with the watering at this time as we can have long fine spells in November and your trees may be drying out more quickly than you realise.

December

Water! Water! Water!

December/January is the time to keep a careful eye on the water needs of your trees. Try to water in the mornings before lunch as watering at night leaves the roots of the trees sitting in water when they should be taking up air not water.

Shade from midday is a good idea for most species used in the art of bonsai. Pines and Cedars are the main exceptions to this, as they love full sun even in the shallowest of bonsai pots.

This is the time to trim those shaggy Maples you have been allowing to grow over spring.

It is also a better time of year to wire trees that need shaping, as the wire won’t cut in so quickly, and trees often set in the new shape quicker.

Unless you are really keen, there is little point in feeding in December/January, as the flush of spring growth has passed.

When you are going on holiday get someone to check on your trees, even if you have an automatic watering system, as things can sometimes go wrong like blocked water jets, pots that have fallen over, or flat batteries in the timer. Check that the jets of your watering system are not blocked even if you are not going away.