Plums are a valuable addition to a suitable permaculture plot, as their fruit can be eaten fresh, are ideal for baking, and plum trees typically provide a bountiful harvest so some of the fruit can be utilized for preserving in jams and jellies.
There are two main types of plum – European and Japanese. Within these groups there are many species available, and the best for your permaculture plot will depend on the climate and soil conditions of your location. Ask local growers or garden societies which species have worked well for them. Many European species are self-pollinating, so you only need one specimen, while many Japanese varieties need two or more trees to pollinate. If planting multiple trees, leave at least 10 meters between them to allow space to mature.
While in theory you can plant the stone from a plum your have just eaten – either from a fruit that you have bought, or one that you have plucked from an existing tree on your permaculture plot – it is not the best way to ensure you get a fruiting plant. The stones do not represent a true copy of the parent tree, and so fruit is not guaranteed. If you do want to take the chance, you will need to germinate the seed so that it becomes mature before planting it in the garden. This is done by ‘over-wintering’, either in the refrigerator for 60 to 70 days or by burying in ground that does not freeze during the colder months (you can use protective cloth over a buried seed to protect it from below-freezing conditions).
The best bet to ensure a fruiting plum tree is to plant seedlings. These will have been created by grafting from fruiting trees to ensure a harvestable crop sets. Source your plum seedlings from an organic supplier to ensure you do not transmit unwanted chemicals into your permaculture plot. A one-year-old is good as it will have had some time to grow and should be able to withstand transplanting.
Like many fruiting trees, plums require several hours of full sun per day – between five and six if possible. However, they can be susceptible to high winds, so if these affect your site, consider placing in the lee of a fence, building or windbreak.
Plums are quite thirsty trees – but they also hate waterlogged soils. Good loamy soils that have more clay than sand are ideal. If you have sandy or chalky soil, the addition of plenty of organic compost prior to planting will give the tree the conditions it craves. A pH of between 5.5 and 6.5 is ideal for plum trees.
As with all fruit trees, you want to dig a hole that is the depth of the root ball on the seedling, and twice as wide (you can mix compost into the soil you dig from the hole and which you will backfill it with, if you like, to give the seedling a nutrient boost). Place the tree in the hole and backfill, being careful not to cover any of the trunk (which could cause it to rot). Tamp the soil down lightly and water very well. If necessary, loosely tie the trunk of the tree to a post to ensure it grows perpendicularly. Plant your plum tree in the fall. Mulch the tree in the following spring to enable good moisture retention during the warmer months. Straw or wood chips are good options for mulch.
When planting your plum tree, you might want to institute a guild that will include plants that will give the tree benefits by their proximity, and receive benefits from the fruit tree in return. Daffodils are good as they repel rodents, which could damage the tree’s root system, while yarrow is beneficial as an insect attractor (flowering herbs can serve the same function). Comfrey is the ideal ground crop as its roots help to keep the clay, loamy soil the plum likes loose enough for good moisture percolation and aeration. It will also help keep weeds away and can be cut and left once or twice a year as “green manure” to provide nutrients to the soil, and thus the plum tree.
Add compost to the soil around the tree in the spring. This will provide a nutrient boost as it begins to set fruit. You plum-10429_640may need to prune in early summer to prevent too many fruits setting. Not only does an overloaded plum tree mean that each fruit is unlikely to develop fully, resulting in plums that are smaller and tarter than typically desired, but it can also cause the branches to sag, putting stress on the tree. You can support heavy branches with struts, particularly in the summer when the fruit is maturing, but you should also pick off juvenile fruit (when its about half the size of the expected mature plums) in early summer. The best rule of thumb is to prune enough so that none of the remaining fruit is touching one another. Each fall, after harvest, prune back the leader branch to encourage more fecund horizontal growth, which will make for an improved, and more easily harvestable, crop the following year.
If you experience cold winters, you may need to protect your young plum tree from the low temperatures, frost and snow, particularly in the first winter after planting, when the tree is trying to establish itself. Cover with gardening fleece, but support the fleece on poles or struts so it doesn’t touch the tree.
Plums are best left to ripen on the tree. They will ripen after picking, but the best flavor develops when they are still attached to the parent. Look for uniform colour and a softness of the flesh to the touch. If you have a large harvest and need to keep ripe plums, place in an open plastic bag in the crisper section of the refrigerator. They should keep well for two to four weeks. Alternatively, you can freeze them; just halve and remove the stone.