The Ultimate Guide to Growing Plum Trees
Including planting, pruning, harvesting, and everything inbetween!Tasty, diverse, and stunning are three words we use to describe our dwarf plum trees. Most people want one in their backyard, but not everyone knows how to grow a plum tree, let alone grow one successfully in a pot. PlantNet® is here to help – learn how to grow a plum tree in ground or in a pot, with advice on pruning, harvesting, and fertilising below!
10 minute read
1- Where to Plant Your Plum Tree
Plum trees require full sun to thrive and produce a good number of delicious fruit. Afternoon shade is ok, provided your plum tree receives sun for the rest of the day. Avoid gullies and other sites exposed to spring frosts which may damage flowers. If planting near other trees or shrubs in a line, try to plant in a north/south aspect so that you reduce the amount of shade they will receive.
In warmer climates, select a site where your plum can be protected from harsh afternoon sun in summer; this will also be a good spot to maximise the chill hours received in winter.
Planting in the ground
Your soil should drain well and be free from known soil issues. You should not plant your plum tree in the same space that other fruit trees have died in without treating the soil. Flat or sloped open areas are perfect for plum trees, and for best results you should improve your soil at least 6 weeks before planting.
2- five steps to planting your plum tree
- Test your soil. Remember: your soil is unique. Ensure you test your soil before changing anything! A simple ribbon test to determine your soil structure, and a pH test to determine soil acidity, are a good start. NSW DPI has a helpful article on soil structure tests. We suggest you do this six weeks before planting – and respond to the results as listed below:
- Clay based soil: Dig clay breakers such as gypsum into your soil with compost or consider creating a mound. We strongly suggest a mound as filling your planting hole with well-draining soil mixes from a store will create a dam where water will accumulate and create root issues. Creating a mound will reduce this affect greatly.
- Sand based soil: Sand based soils need regular amendments to improve water and nutrient retention. Dig in organic matter such as composted manure, compost, or soil conditioners – or, consider creating a mound or using pots.
- Silt based soil: Silt based soils can compact quickly and need amendment to reduce this effect. Dig organic matter into the soil and in very compacted silt-based soils you may like to add sand alongside organic matter – or, consider creating a mound.
- Loam soil: This is ideal – continue to nurture your healthy soil by adding organic matter.
- Acidic soils (low pH): To raise the pH of soil, amend with garden lime.
- Alkaline soils (high pH): To lower the pH of soil, amend with sulphur.
Consult a local horticulturalist for more specific advice, and always follow product directions of use. Otherwise… Move to step 2!
2. Work with your soil. For general soil conditioning, use organic material, such as composted manure and compost. Dig the organic material into your soil before letting the site rest for six weeks. Some sites require more time to prepare than 6 weeks; sometimes working with your soil means that you should plant your plum tree in a pot instead!
3. Get digging. Dig a hole twice as wide as the root system. Ensure you loosen the soil at the bottom of the hole. If planting a bareroot plum tree, create a mound at the base of the hole to splay the roots over.
4. Place your plant. Place your plum tree in the hole and backfill the hole with well-draining soil (see above for our advice in clay soils). The soil should come up to the height of the pot or soil line from the nursery, or 5-10cms above the roots (if soil line is washed off) and always below the graft. Stake your plum tree to ensure strong, upright growth.
5. Mulch your tree and pull out a hose! Mulch the surface of the soil with straw-based mulches, such as sugar cane, barley, or pea straw. Bark-based mulches are fine to use too. Water your plant in well with a seaweed solution to promote healthy root growth in Spring.
A young plum tree ready for planting – note the soil line above the roots!
3- Do plum trees need fertiliser?
Quite simply – YES! If you’re buying a potted plum tree or planting in a pot, most potting mixes have fertiliser which will expire (usually in late summer and late winter), and you should fertilise. The best time to fertilise your plum tree is once it starts to grow after winter.
PlantNet® has created a great guide for fertilising deciduous fruit trees, including plum trees, in pots from trial work completed by PlantNet® over a 3 year period. Please note that these recommendations are specific to apples, pears, and peaches but will also help with plum trees.
Plum trees aren’t as heavy feeders as pome fruit (apples and pears) and peaches – a complete fertiliser will suffice for most plum trees, with European plum trees sometimes requiring additional potassium, more alike pome fruit. Organic fertiliser can be used but note that the application rate is generally much higher than synthetic fertilisers.
All fertilisers should be watered in well after application.
4- Watering plum trees
In winter a small amount of water once a week is all that’s needed to prevent the soil profile from drying out too much. In spring you can increase to watering about twice a week, and in pots to every two days or so. In summer, 2 to 3 times per week in hot/dry periods will suffice.
For pots, the best practice is to use your hand to measure the moisture level of your potting mix. When digging into the top 5cms of potting mix you should look for any sign of moisture – if you see moisture, don’t water; if the potting mix is completely dry, water well.
Using wetting agents, mulch, and drip lines are all good ways to decrease the amount of time you need to spend outside with a hose.
5- Common plum tree pests and diseases
PlantNet® has developed a comprehensive list of common pests and diseases for fruit trees in our article – Common Fruit Tree Pests and Diseases.
Timing of pest control is extremely important with plum trees and deciduous trees in general, as tree dormancy influences which pests will attack at what time. Of most significance to your plum tree is birds who will eat (or half eat!) your plums just as they’re ripe. Ensure you net your tree or, in small spaces, individual fruits.
Plum fruit are most susceptible to brown rot, so care must be taken in planting site selection to avoid particularly damp patches of soil which encourages the disease. Spray plum trees with an organic Bordeaux spray as you would peaches and nectarines at leaf fall and prior to bud swell to avoid most pest and disease problems.
Bird damage on a plum – netting is the best solution!
Brown rot affecting a crop of plums.
Spraying a bordeaux spray at leaf fall and prior to bud swell can prevent brown rot.
6- Pruning plum trees
Pruning plum trees is a good way to promote a healthy tree and tasty fruits. The best time to prune is when your plum is dormant in winter. Plum trees fruit mostly on spurs that originate from 2-year-old wood and have the potential to continue producing fruit from these spurs in following years. Therefore, pruning should involve removal of dead/diseased wood, branches that cross over, or untidy branches. You can additionally shorten branches that become too tall, however purchasing dwarf varieties will reduce this need.
There are several methods of pruning plum trees which should be chosen by you to suit your specific space requirements. Most home gardeners prune in one of three ways: using a central leader, an open vase, or espalier/palmette. We will expand on these methods below.
Central Leader
The overall aim of this method is to allow one upright branch to be the main leader. Lateral branches grow outwards from this main leader and fruiting spurs develop from these on young wood. This method of pruning creates an upright taller tree, which is easy to maintain in tight spaces. Don’t be fooled by a ‘taller tree’ – remember, our dwarf fruit trees still grow up to 2.5m! This is a great method for potted dwarf plum trees, especially Santa Rosa and Mariposa, which tend to have an upright habit.
Open Vase
This method involves the removal of the leading branch and selecting four or five evenly distributed outwards facing branches. The aim of this method is to produce a shorter, wider tree. This system can be more difficult to control than the others if left unmanaged when older, and it requires more space. It is, however, more intuitive for beginner gardeners and provided you have the space, is a great method to get started.
Many plums grow naturally open without removal of the central leader, and pruning will be as simple as removing inward facing growth that doesn’t conform to the open vase shape.
Espalier/Palmette
Espalier is one of the most popular methods of shaping fruit trees and involves the training of limbs to grow horizontally from a leading branch along a flat surface/wires.
A better and more specific method for plum trees is to train them in a palmette style. This involves training limbs to a 45-degree angle on a flat surface/wire rather than the traditional 90-degree angle of espalier. Palmette training produces more fruiting laterals on plum trees than traditional espalier. This method is great for gardeners with limited space and those of us looking for an attractive feature tree.
Central Leader
Open Vase
Espalier
Palmette
7- Seven tips for growing dwarf plum trees in pots
- Choose a pot with a diameter greater than 55cms. Avoid pots that taper towards the bottom. Ensure the pots have drainage holes.
- The larger your pot, the happier your plum tree will be.
- Our recommended potting mix is 70% premium potting mix and 30% coir peat.
- If you don’t have access to coir peat, the highest quality potting mix will suffice.
- Always mulch the top of the pots.
- Use soil wetters or water crystals to assist with moisture retention, particularly over dry, hot periods.
- Take note of the lifespan of the controlled-release fertiliser in your potting mix – it will expire, and this is when you will need to reapply fertiliser to your plum tree again.
- Maintain potting mix quality with organic materials like compost, worm juice, seaweed, and rock minerals but keep in mind your application rates and how they may affect your fertiliser regime.
- Avoid allowing the potting mix to dry out completely between watering – this will eventually create hydrophobic soil. Try to check your plum tree once every two days, even if you don’t water for 6 days!
8- Plum Harvest Guide
The below guide shows the ‘normal’ picking period of each plum variety to be harvested in a normal year and a standard growing region. If you have a heavy crop coming, you might like to thin the fruit so that those you do eat, taste even better (and the remaining fruit will be larger in size too)! See our article on Fruit Thinning which will give you a good head start.
Note – climatic variation can change harvest time between locations and between years.
9- PlantNet® Plum Pollination Guide
Green indicates compatibility; red indicates self-incompatibility.
Note – pollination partners vary due to climatic differences between locations and years. These are suggestions only.
When fruit drop occurs soon after fruit set, you can usually put it down to poor pollination – even when you have pollination partners. Bees aren’t overly attracted to plums, therefore a great way to encourage them is to ensure you have plenty of bee-attracting plants around them.
For more relevant information, see links below:
The Ultimate Guide to Growing Fruit Trees
Retail Stockists – Deciduous Fruit Trees and Ornamentals
References
Glowinski, L, 1991. ‘The complete Book of Fruit Growing in Australia’, Lothian Publishing Company PTY LTD, Melbourne, Australia.
Lines-Kelly, R. (1992). Check your soil structure. <https://www.dpi.nsw.gov.au/agriculture/soils/guides/soil-structure-and-sodicity/check#:~:text=Place%20a%20cup%20of%20dry,particles%20settle%20within%20five%20minutes.>. First accessed 23rd June 2023.
Persley, D. (1994) Diseases of fruit crops Vol 1. Brisbane, QLD: Department of Primary Industries.