Robin Gale-Baker, from Sustainable Macleod, discusses growing various fruit trees. She has also written articles for this website about growing broad beans, cauliflower, eggplants and capsicums, other vegetables, apricot trees, persimmon trees and herbs. Also articles on mulch and growing techniques.
Tending the raspberry patch (July)
Now that winter is here, its time to tend the raspberry patch. First, you will need to know whether your raspberries are autumn varieties (e.g. Autumn Bliss, Autumn Heritage) or summer (e.g. Chilicotin, Chiliwack, Willamette) as they are treated in different ways. Both require wire supports. Autumn varieties prefer 2 sets of parallel wires each with 3 strands at intervals of 60cm and the taller summer varieties a single set of parallel wires with 4 strands at an interval of 50cm. Autumn varieties fruit on first year canes called primocanes and are usually pruned to ground level after leaf fall – pruning earlier or much later than leaf fall reduces the crop the following season. After pruning, add well composted manure to the bed. Then, in the spring when the canes reach 60cm in height, tip prune them and tie them to one of the horizontal wires – this will result in branching and more berries. Summer varieties fruit on second year canes called floricanes and are more complicated to prune. Canes that have fruited won’t fruit again, so look for dry, brown canes and prune these back to ground level. At the same time, look for new shoots or canes which will be green and tie them to your horizontal wire. Then tip prune them and fertilise with well composted manure. Both autumn and summer raspberries sucker. The suckers should be removed to keep the strength in the main cane. Cut the suckers rather than pull them.
Which fruits continue to ripen after being picked? (May)
Pomegranates and figs are ripening beautifully at this time of year but must ripen on the tree (they do not continue to mature once picked). How do you know when they are ready? In the case of pomegranates, look for split skins. Once this happens to a few on the tree, all will be ready. It is worth investing in a pomegranate press (available online for less than $60) to extract the juice as the press will avoid inclusion of any of the bitter pith which ruins the taste. In the case of figs, look for wilting of the stem and give a gentle squeeze for softness. Note that pomegranates and figs that look like they are ready by colour often still have a way to go.
[Editor’s note: fruits that continues to ripen after being picked are called ‘climacteric’, whilst fruits that stop ripening after being picked are called ‘non-climacteric’. The archetypal climacteric fruit are tomatoes and bananas. Avocados, peaches and plums are also climacteric. The archetypal non-climacteric fruit are citrus. Grapes and all the curcubits (cucumbers, pumpkins, etc) are also non-climacteric. For each fruit, our North East Melbourne fruiting schedule lists whether it is climacteric or not. Climacteric fruit will typically only continue to ripen if kept at room temperature so you can defer this by putting them into the fridge until you want them to ripen.]
[Editor’s second note: have you ever seen the flower of a fig tree? The answer is ‘no’ because the flowers are actually inside the fig (and the fig is therefore not technically a fruit). Whilst common figs do not require pollination, they do not taste that good. Rather, the best tasting type – Smyrna – does require pollination. But it only has female flowers so needs to be pollinated by a wild/caprifig (whose fruit are inedible). As the flowers inside the fig are inaccessible to all normal pollen vectors, pollination is done by tiny wasps. The wasps hatch in the caprifig, then mate, then the females leave to find new figs to lay their eggs in. As they leave, they get covered in pollen, and pollinate the next fig that they enter. If it is a caprifig, then baby wasps are born but no edible fruit results. If, however, it is a Smyrna, then edible fruit results but no baby wasps are born (the Smyrna flowers are too long for the wasp to lay its eggs in). Luckily for you, the female fig produces an enzyme that digests the dead wasps completely and so the crunchy bits inside a fig are seeds, not wasp parts. For more info, watch this video.]
Growing passionfruit (November)
Passionfruit, like blueberries, require quite acidic soil. They need a pH of around 5.5-6 so add granular sulphur, dig it in and then water in. Adding sulphur will also help release various trace elements like zinc and iron. Passionfruit are heavy feeders of iron so you may need to add some iron chelate. In our climate, Nelly Kelly is the best variety. The tropical varieties are sensitive to frost and do not survive. Planting passionfruit in front of a north facing wall gives them the best chance of success. They thrive in full sun and need wind protection and strong supports to grow on, as the vine quickly becomes very heavy. Prepare the soil by incorporating compost and well-rotted manure in an area 2 metres’ wide. Let the tendrils grow to the top of your trellis and then nip out the growing tip which will allow laterals to develop. Passionfruit require around 140 litres of water a weekly when they are fruiting. This is the equivalent of around 15 fullsize watering cans. Without this amount of water, flowers and fruit will drop.
Growing blueberries (October)
Blueberries can be grown successfully in North East Melbourne but they do require exceptional soil preparation. The soil needs to be quite acidic with a pH of 4-5. However, our soils are naturally closer to 7 (neutral) so the pH needs to be reduced by at least 2 points. To do this, add granular sulphur, work it into the surface, and water it in. You may have to do this several times and it is best to begin the process 3 months before planting. Once your blueberries are established, you can assist the soil remaining acidic by digging in sphagnum peat carefully around the shallow roots once a year, and fertilising with an acidic fertiliser. However over time, the soil will return to its natural pH and your plants will suffer. Remedial action is then required to again reduce the pH. Plant in a sunny, well-drained position. One of the best varieties for our area is Brigitta.
[Editor’s note: in The Complete Book of Fruit Growing in Australia, Louis Glowinski recommends using well-rotted chicken manure as the fertiliser. His argument is that blueberries don’t like either nitrates or chlorides and that many commercial fertilisers contain such compounds.]
[Editor’s second note: one way of helping to keep the soil acidic is to use pine needles as the mulch. There are a number of pine trees along the Yarra, for example at Lenister Farm – simply take some big bags and scoop the needles off the ground.]