When to plant
Unless there is a risk of winter frost damage, the optimal time to plant fruit trees in a summer rainfall climate is in autumn. This takes advantage of the normally good soil moisture from the summer wet season. Take care, however, to monitor soil moisture closely through the normally hot and dry spring and early summer. Where a site is subject to heavy frosts it is better to plant in spring.
In mild climates trees can be planted all year round as long as adequate water is available. Avoid planting trees when conditions are windy or hot and dry, and during the hottest part of the day.
If trees have to be stored while awaiting more favorable planting conditions, hold trees in a well-protected and shaded area, preferable not in contact with soil (place on plastic sheeting or concrete). Maintain a careful watering program as trees can easily stressed and set back.
- Check soil texture and drainage
Tree roots need both moisture and oxygen for growth. Soil texture and drainage should be checked before planting. Sandy soils are porous and are usually well drained. On the other hand, clay soils have much smaller pores and retain water for long periods of time.
To test your planting location for soil drainage you will need to dig a hole about 40cm deep. Fill the hole with water and let it stand overnight. If the water has not drained by morning you have a drainage problem on your hands. If the test indicates poor soil drainage or the area is subject to high rainfall that leads to periods of waterlogging, it is best to plant the trees on a raised bed or mound. Waterlogging or “wet feet” is the major cause of root rot and is a serious problem that affects tree growth and survival.
Mound planting is especially helpful in improving growth and reducing root rot. Mounds can be made by adding good sandy/ loam landscape soil or by digging the top soil from the surrounding area and using it to form mound on the planting site. The mound should be at least 45-80cm high and 90cm in diameter.
Adding Gypsum (¼ of a bucket) per hole can help break up the clay and improve drainage but if the soil still drains poorly after adding gypsum then it is best to plant on a mound. Adding gravel or crusher dust to the planting hole will not improve drainage.
In some groves installing a surface and/or subsurface drainage system may be a viable option to improve the drainage of the grove site prior to planting. Surface drainage involves contouring the surface of the ground or installing a spoon drain to create an artificial “creek” to direct water away from wet areas. Subsurface drainage using slotted ag pipe and gravel trenches requires an understanding of soil types and soil water movement and is best designed by a drainage professional.
- One to two days before planting, thoroughly water the tree sites to a depth of 30 cm.
- Dig a hole slightly deeper and wider than the pot/ bag. Back fill with some of the topsoil and press down firmly so that the surface of the potting mixture is the same level as the soil surface. If using a posthole digger or auger to dig the holes ensure that the sides of the hole are broken up to reduce any ‘polishing’ effects which may restrict later root growth.
- A small amount (100g to 150g) of pelleted or composted manure or a teaspoon of slow release fertilizer may be added to the backfill soil in the hole. However, do not place inorganic nitrogenous fertilizer or fresh manure into the hole, as these may burn the roots.
- Before planting, water the tree well.
- Cut the bag or tap the pot from the tree and inspect the roots. If the roots are matted around the edge of the root ball, make shallow, vertical knife cuts through the matted roots at 3 or 4 points around the circumference. If the matting is less obvious, gently ruffle the edge of the root ball with the fingers to expose the potting mix.
- Place the tree in the hole, ensuring that the roots at the bottom are well spread. Half-fill the hole with soil, gently pressing the soil into contact with the root ball. Complete the filling process and firm the soil down gently and leaving a slight basin around the tree to hold water. Water again.
- Mulch trees with a coarse mulch such as compost, bark, or stubble to a depth of 10 to 15 cm. Try to keep the mulch away from the trunk to reduce the risk of trunk canker.
- Do not allow the root ball to dry out after planting. Irrigate or hand water 2-3 times per week for the first few weeks, particularly where conditions are dry.
- If planting in summer or sunburn is a risk, exposed trunks can be painted with white water-based paint to reduce the risk of sunburn and heat stress.
- If hares or rabbits are present it is advisable to place a tree guard around the trunk to protect the first 40cm bark from animal damage. Builder’s sisalation (laminated aluminium foil) can be formed into a cylinder, wrapped around the trunk and tied at each end. Alternatively plastic tree guards or trunk protection netting can be used.
- Most trees will need staking for the first three years after planting. If you are planting a row of trees running a single trellis wire at 900mm above the ground can be used as an alternative to using a heavy stake on each tree. With the trellis system a cheap bamboo stake (10-12mm diameter) is tied to the wire at 900mm and the tree is trunk secured to the stake in a couple of places.
This information is a general guide for small scale plantings only. For larger commercial plantings it is recommended that advice is sought from a horticultural consultant and that soil tests (structural, nutritional and pH) and deep ripping of the site is undertaken several months prior to planting.