Growing and transplanting pohutukawa and rata

Before planting, check with your local council (Parks Officer) or DOC to ensure the species you select is ecologically correct for your area.

Pohutukawa and rata grow to become huge trees, which can cause problems if planted on small suburban sections, or near fences or other structures on farm land. The location of underground drains and water pipes also needs to be taken into account. 

Below you will find all the information about growing or transplating pohutukawa or rata.  You can also print our information sheet on How to Grow Pohutukawa or Rata.

Planning ahead

It will take at least two or three years from the time seed is gathered, until a seedling is ready for planting out. The following factors must be taken into account when deciding where to collect seed from:

  • Maintain genetic integrity - most importantly, don't bring in seed from another part of the country. Locality can affect many important factors: the genetic basis of the plant's hardiness, drought resistance, seed viability, size, shape, colour and even its resistance to pests and disease
  • Try to gather seed only from trees that you know are 'native' to your area. This can be difficult to tell but the following guidelines will help:
    • Take seed from trees that are growing naturally rather than those that have been deliberately planted. No matter how attractive they appear, avoid taking seed from trees growing in or near cultivated areas such as gardens, council picnic sites and parks
    • Ensure the parent tree is located well away from other types of pohutukawa and rata (e.g. M. kermadecensis or M. colina 'Tahiti') because they could cross-pollinate to create hybrids
    • Avoid roadside plantings because these trees are generally of unknown origin. Planting trees from locally-sourced seed of good genetic stock is a relatively new concept in New Zealand. Seed for older plantings may have originated from other regions and not be genetically well-adapted.
  • Before planting, check with your local council or the Department of Conservation to ensure the species you select is ecologically correct for your area.
  • Identify attractive, healthy parent trees - ideally the parent trees should flower abundantly and over a long time span because the flowers are an important food source for nectar-eating birds.  This doesn't mean the parent trees have to be flowering heavily when you find them. Look for good trees that show signs of having already flowered, or trees that still have lots of flower buds, and note those as well
  • Don't be put off by insect damage -lots of native leaf-eating insects live on pohutukawa and rata. The species is home to a huge community of invertebrate species, most of which have co-existed well with their host for millions of years. Insects are generally only a problem to the tree's health when it is already sick.

Where to plant your seedling or young tree

Pohutukawa and rata grow to become huge trees, which can cause problems if planted on small suburban sections, or near fences or other structures on farm land.

The location of underground drains and water pipes also needs to be taken into account. Plant the tree as far from underground pipes as possible - at least 2 metres.

Avoid planting southern rata in particular near joins in old water and sewerage pipes because in its natural habitat the long roots are known to seek out cracks in rock. (This should not be a problem with modern plastic piping because there are fewer and tighter joins.)

Collecting seed

Pohutukawa seed matures in the autumn, and rata in the winter.

  • Pick a dry day, hold a large bag over a cluster of seed capsules and give it a good shake. This should produce thousands of tiny seeds.
  • Alternatively, put a sheet on the ground, tap the branches and stand clear.
  • Take care when gathering seed because it is very fine. The seed can cause itching and take several washes to get the seed out of your clothes!
  • Collecting seed from Northern rata can be quite difficult because the trees are very tall and the seed capsules are therefore difficult to access.
  • Try propagating from cuttings if seed is not accessible.
  • Use seed quickly: Pohutukawa and rata seeds lose their viability quickly. If absolutely necessary, store them temporarily in the fridge (not the freezer).


The following steps show how to successfully grow seedlings from the seed you have collected

  • Prepare a number of shallow seedling trays. Fill to 5 cm with sterilised seed raising mix or leaf-mould and loam (finely sieved and free of weeds)
  • Sow the seed thinly on the dampened mix. Thick sowing may cause the seedlings to rot
  • Cover the seed very thinly with fine sand (pumice sand is recommended) - the seeds should be barely covered. Lightly water. Note: avoid coastal sand because its high salt content may kill the seedlings.

 

  • Cover the tray with a sheet or two of newspaper (or keep the trays out of direct light / in a low light area) for a maximum of a week
  • Check from seven days on. As soon as germination starts, remove the paper and water lightly (with a fine mist spray). Keep the soil just moist. Don't over-water

  • Keep the seedlings in a sheltered spot out of the wind, direct sun and away from frost
  • After about three months, the seedlings should be around 1 cm high with four to six leaves. At this stage, prick them out into separate containers (plastic yoghurt and margarine containers with drainage holes poked in the bottom are ideal)

  • The planting mixture should be a commercial potting mixture or a leaf/loam mixture with added fertiliser. Ensure the plants are well-watered
  • When the seedlings have recovered from the replanting (after three to four weeks) progressively introduce them to stronger light until they can tolerate full sunshine
  • As the plants grow pot them into larger containers
  • Trees need to be grown for two years before planting out
  • If scale insects or psyllids become a problem, treat every four weeks during the growing season (spring and summer) with a light spraying oil. Make sure you use the sort of oil that does not harm ladybirds or other useful insects. Conquer Oil is most commonly used, although it is not always necessary because most plants outgrow psyllid attacks.

Growing from cuttings

While a potentially tricky process, growing cuttings has its advantages. The tree is more advanced in its development at the time of planting and, perhaps more importantly, it is a genetic duplicate of the parent tree.

However, a dead twig is the most common outcome of taking a cutting from a pohutukawa or rata, treating it with rooting hormone and putting it in a pot.

You may get a good strike rate from semi-hardwood (winter) cuttings if you have access to nursery facilities with bottom heat.

Aerial rooting is the most reliable technique despite being more labour intensive. The idea is to grow roots on the living tree. The soft outer bark is removed to stop nutrients travelling away from the tip while the inner wood is left intact, allowing nutrients to build up and feed the growing root system.

Use the following process when taking aerial cuttings from pohutukawa or rata:

This method is no good for taking cuttings far from home because you need to periodically check the shoot until it is ready for removal.

  • Spring and autumn are the best times to take cuttings. If this isn't possible, make sure the bark is still green
  • Choose a one or two year old growing tip low on the tree. The stalk should be about as thick as a pencil
  • About 40 cm from the end, strip leaves away to create a 15 cm clear working zone

        

  • Ring-bark in the middle of the zone, about 2 cm wide, cutting away the bark and soft outer layer but not cutting into the wood
  • Rub Seredix 2 or 3 rooting hormone into the cut
  • Enclose in a fist-sized ball of damp (not wet) sphagnum moss
  • Wrap clear cling film around the ball of moss, and use plastic tape to seal the cling film tightly to the stalk at either end

         

  • After five or six weeks, depending on the season and growing conditions, roots growing through the moss will be visible through the cling film
  • Cut off the shoot, complete with root ball. Keep the cutting in its wrapping if you areunable to plant immediately

         

  • Remove cling film and tape and plant in moist potting mix. Keep damp and shaded for the first week or so. If necessary, encase the leaves in a plastic bag to retain moisture during this


Planting seedlings and young trees

Good forward planning and site preparation are the keys to successful planting.

  • The best time to plant is in autumn/early winter when the ground is still warm and there is likely to be good rainfall. The shorter days also mean the tops won't grow too much, enabling the tree to put its energy into developing a good root system
  • If the planting site is prone to ground frost spring may be a safer time to plant. Smaller trees probably will not survive any frost because they will get burnt off and not recover. Larger trees are more likely to survive frost damage
  • More detailed forward planning is required if planting pohutukawa in fully exposed coastal sites. Here it is advisable to plant a semicircle of flax and ngaio on the windy side, wait two years until they are two metres high before planting the pohutukawa
  • Shade cloth can be used for shelter if you do not have time to wait for a nursery crop to grow.
  • While grasses and weeds may look unsightly, for the most part they don't seem to cause seedlings too much trouble. Grasses such as Kikuyu are normally controlled through spraying or weeding, but occasionally they may actually help a young tree to become established by forming a 'nursery' cover that protects the tree from the elements
  • Choose the planting site carefully, taking into account the tree's natural habitat and growth potential
  • Dig a hole that is as deep as the tree's collar (the part where the trunk turns into the root system)
  • Avoid planting any deeper because this offers the tree no benefit and could cause rot to set in
  • In dry conditions mix a small amount of Crystal Rain into surrounding soil to retain moisture
  • Dig compost and blood and bone into the planting hole (allow up to a couple of handfuls of each, depending on the size of the tree). Avoid fertilisers that are high in nitrogen because these can burn new roots. Note: digging nutrients into the planting hole may not be practical for large-scale plantings
  • Plant the seedling or tree and 'heel' it in so that it sits firmly within the soil

         

  • Apply mulch
  • Water the newly planted tree or seedling and ensure it does not become too dry while it becomes established. It is particularly important to water trees during their first summer, especially if conditions are very dry.

Protecting young trees from pests and stock

Animals such as livestock, rabbits, possums and goats can quickly kill a tree.

An almost foolproof way of ensuring that very young trees survive summer drought and attack from rabbits and possums is to grow them inside a large, bottomless bucket. Drive a stake on either side of the tree and slide a 20 litre bucket with the bottom cut out down the stakes. Mulch heavily outside the bucket.

Keep the buckets in place for a maximum of two years, then slide them up the stakes and tie the trees to their stakes. Mulch 5 cm deep x 100 cm across.

Trees planted on farmland must be well fenced to protect them from grazing animals.


Transplanting

It is not advisable to transplant trees larger than two metres because they are much less likely to survive transplanting than smaller trees.

If you want to move a larger tree it is advisable to seek assistance from an arborist with experience in relocating large trees - and the necessary equipment.

Small and medium-sized pohutukawa and rata transplant well, but careful planning is required for a successful result. It is best to start the process in late autumn / early winter while the tree is dormant and the soil is damp.

Transplant the tree by early spring at the latest.

  • Carefully plan the tree's new location, taking into account whether there is room for the tree to grow without blocking light, damaging drains or other structures. Consider whether the site meets the tree's own requirements
  • Before transplanting, undertake any necessary pruning to remove poorly-positioned, damaged or diseased growth
  • Cut around the root ball with a sharp spade, aiming to reduce it by about one third. As a rule of thumb, the root system extends as far as the tree's drip-line. Angle the cut inwards towards the roots to trim the root mass on each side and beneath. Work your way right around the root mass. This prepares the plant for lifting

         

  • It is not necessary to also dig a trench around trees under two metres
  • Ensure the tree does not become too dry - but avoid over-watering
  • Leave it for two or three months. This will allow for new fine roots to establish
  • Meanwhile, prepare the new site for the tree by digging a hole and digging in a couple of handfuls each of compost and fertiliser such as blood and bone. Avoid fertilisers that are high in nitrogen because these can burn new roots
  • When ready to transplant, carefully lift out the tree so as not to disturb the root ball and transplant it

         

  • Ensure the hole is no deeper than the collar
  • Plant the tree and 'heel' it in so that it sits firmly within the soil

          

  • Apply mulch
  • Spread a handful of slow release fertiliser around the tree's drip-line once new growth starts to appear. Again, avoid using fertilisers high in nitrogen because the aim is to initially establish a healthy root system, rather than vigorous leaf growth
  • Water the newly planted tree or seedling and ensure it does not become too dry while it becomes established.