Grapefruit cultivation

Grapefruit cultivation

In the small family citrus grove, some examples of grapefruit, a plant with juicy and slightly sour, but very healthy fruits. The plants bear fruit generously even if they are grown with natural techniques and own means of organic farming, those we recommend in this article.

So let's see what the plant is like and how it can be grown both in a family garden and for income productions, although in the two situations there are obviously differences in setting and management. We have already talked about lemon and orange, let's continue to explore the citrus grove.

Let's find out then from planting to harvest, passing through the pruning, all the steps required for good plant care, learning how to defend the tree from diseases and harmful insects using natural treatments rather than toxic pesticides.

The grapefruit tree

The grapefruit (Citrus x paradisi) is probably a natural hybrid between Pomelo (Citrus maxima) and thesweet orange (Citrus sinensis), but according to some scholars it derives instead from a mutation of the pomelo. The pomelo in Liguria is called sciaddocco and is the citrus fruit with the largest, thick-skinned but not juicy fruits.

The grapefruit tree, originally from Barbados, is a plant that can reach a maximum height of about 12 meters, tends to form a globose hair and very dense. The leaves are oval and dark green in color, the flowers are large and gathered in inflorescences reminiscent of clusters, hence the English name of grapefruit, which means "fruits gathered in clusters".

THE fruits of grapefruit are hesperides like those of other citrus fruits, and may have yellow or pink skin and pulp, in both cases they are large fruits in the shape of a slightly flattened ball.

Climate necessary for cultivation

Like other citrus fruits, grapefruit also requires a rather mild climate, where winters do not reach intense cold, therefore it is necessary to avoid planting them in positions where pockets of frost can form. Frost is harmful for this species, also depending on their duration, and especially if accompanied by a considerable humidity of the air. Excessive temperatures, however, also have their drawbacks, stopping fruit development and causing leaves and branches to dry out.

In windy areas it is also important to provide for gods windbreak systems, to avoid damage from drying of leaves and twigs or, in severe cases, from flaking of the branches. In coastal areas the winds can also be rich in salt and this is a further danger. Live windbreaks, such as cypresses or other plants, obviously have a slow growth, so you can initially install fences, which however reduce the impact of the wind.

The ideal terrain

If you intend to start planting a real citrus grove, whether small or large, it is worth doing an in-depth analysis of the terrain you have, by contacting a specific laboratory. In general citrus fruits prefer deep soils, at least 1 meter, to adequately deepen the roots. The rock and the water table must therefore be deeper, to avoid root rot.

How texture the ideal is a medium-textured soil, without excesses of clay or silt, enough sand and little skeleton, ie stones. Even if they adapt well to different soils, which differ from the optimal ones, surely those strongly clayey (with more than 35% clay) can be difficult for grapefruit and other citrus fruits, as well as those rich in active limestone (more than 30% ) and very saline ones, i.e. with a high content of chlorides, sulphates, carbonates and bicarbonates.

The best pH is close to neutral or slightly acidic. If the soil is very loose, irrigation must be intensified, as well as the distribution of organic matter which, as with any crop, is always the basis of soil fertility.

Plant a grapefruit

To plant a grapefruit tree you must first choose rootstock and variety. As for pollination, citrus fruits are self-sufficient for the fertilization of flowers and therefore for setting, therefore even isolated plants produce.

Choice of rootstock

When choosing grapefruit plants to buy, we should inquire about the rootstock that was used. For citrus fruits the bitter orange the classic rootstock has been used for a long time, but i citrange, hybrids between sweet orange and poncirus, which offer tolerance to the Tristeza virus. The poncirus instead, with its resistance to root rot, it is a rootstock suitable for land at risk of stagnation water.

The transplant

Past the risk of frost, in spring, we can plant grapefruit plants. Doing it in autumn would involve a greater risk of root rot, while spring allows for rapid rooting and arrival in winter with a good accumulation of reserve substances.

If you plant a single plant, you simply proceed digging the hole, which must be large, well beyond the clod in which it is contained. If the plants to be placed are many, to be placed in an orchard, the rows must be traced well straight and the holes aligned, and in this case surely doing them all by hand with a shovel becomes unthinkable, and you have to resort to a power drill.

There excavated earth must be mixed, in the most superficial layers, with a generous dose of soil conditioner, such as compost or manure, both fully mature. It is good to add some s toopelleted heel and of handfuls of rock flour, which provide valuable nutrients, and remember to distribute them also in subsequent years.

The plant fits straight into the hole, keeping the same level of the surface equal to that of the clod of earth.

Planting layouts

Indicatively, the same planting sixths recommended for oranges are good, i.e. an average of 5 meters between plant and plant.

Prune the grapefruit

As with all fruit trees, pruning is a very important job, both to contain and rearrange the foliage, and to stimulate production. The most natural and suitable form for grapefruit is the globe in full hair, according to which it can grow with its typical posture making the fruiting formations especially in the lower part.

During the first years after the transplant, the training pruning, with which we direct the plant in the natural globular shape. After that, interventions aimed at maintenance are carried out in the following years.

Production pruning

To set up and carry out a correct annual pruning it is necessary to take into account that citrus fruits bear fruit on the branches of the previous year, and that the period of maximum accumulation of reserve substances they do in the period between February and March, which is the one in which cuts must be avoided. Cuts should also be avoided in very cold and very hot periods.

The hair goes anyway lightened without exaggerating, thinking of keeping the branches sufficiently lit inside and avoiding that the branches become too loaded with fruit with the risk of breaking. THE dry branches and those heavily infested with scale insects should always be cut, as well as i suckers, branches with strong vertical growth.

How it is grown with organic methods

Irrigation

THE water needs citrus fruits were calculated at around 2000 mm per year, and this also applies to grapefruit. Consequently, given that the contributions that arrive with the rains in some periods are almost always insufficient, it is important to set up a irrigation system, or if you have only one plant in the garden, remember to water it consistently with the hose. In any case, the foliage must not be wet, so an irrigation method that is absolutely recommended wet the soil and not the aerial part, such as the dripline. The most delicate period, in which the plant can suffer the damage of drought, and lat the stage following the fruit set, which could fall.

Mulch

There mulch it is always useful to counteract the emergence of weeds, and also around grapefruit seedlings we can arrange it, for example by distributing a circle of straw, hay or withered grass all around its base. The layer must be thick enough, about 10 cm, otherwise the most stubborn grass will still appear.

Disease defense and prevention

The illnesses as they always have to be prevented, avoiding irrigation by sprinkling and fertilizing in moderation. The diseases that grapefruit can undergo are those common to other citrus fruits, they can be treated with copper-based products, but we can also try to replace this metal with zeolites, mineral fines that by absorbing moisture in the vicinity of the vegetation, decrease the probability of the disease occurring.

  • Gummy collar. It manifests itself with the issue of a gummy flow from the collar and a wet spot on the bark, and it's caused by a bacterium. The leaves turn yellow and begin to dry out, but it is important not to reach this stage and to intervene earlier.
  • Sore dry. It's about a tracheomycosis, a fungal disease that sees the establishment of the pathogen within the woody vessels. The first symptoms are the leaves that turn yellow and fall, and the drying of the twigs, and finally the trunk, to arrive at the death of the plant.
  • Fumaggine. Although it is not a disease in the strict sense, because in fact the fungi settle on the honeydew of the aphids, causes a decrease in photosynthesis, with the covering of the leaves of a blackish dusty layer, as if it were smog or smoke. The fight against honeydew-producing insects also solves this problem.

Defense from parasitic insects

Grapefruit, like other citrus fruits, can be attacked by some parasitic insects which fortunately can be held in check with ecological means and good prevention. The most common are:

  • Red spider. The mite steals the sap from the plants and the leaves appear blistered and subject to falling, but even the small fruits can fall more abundantly. To stem the presence of this parasite it is necessary to avoid fertilizing too much and letting the foliage grow too dense, then sprinkle often decoctions of garlic and possibly deal with natural pyrethrum, in the doses and methods expressly indicated on the packaging.
  • Mealybugs. There mealy cochineal (also called cotonello), Planococcus citri, attacks citrus fruits but also other plants. It predominantly attaches to the petiole by subtracting lymph. Another note cochineal, Icerya thoussi, instead it attacks the lower page of the leaves and also the branches, and furthermore you can find the low scale cochineal of citrus fruits and the red cochineal, both capable of stripping the plant of many of its leaves. To limit the attacks of scale insects, fern macerates can be sprayed constantly, and treated with mineral oils, also allowed in organic farming, if this natural product is not enough.
  • Aphids. The brown aphid, the black aphid and the green aphid of citrus fruits cause similar damage from leaf curl by sucking of sap, fumaggine is honeydew sticky. They must be eradicated because in addition to this direct damage, they are potential vectors of viral diseases. Then you have to spray often extracts of nettle, garlic or hot pepper, also using the Marseille soap when that's not enough. Furthermore, it is always worth remembering that avoiding dealing with aggressive insecticides is the prerequisite for the natural predators of aphids, such as the well-known ladybirds, to establish themselves in the environment.
  • Serpentine miner of citrus fruits. This moth lays its eggs on the leaves during the summer period and the larvae live at the expense of the leaf tissue by digging tunnels. You can do treatments with Bacillus thuringiensis or with azadirachtin (neem oil).
  • Thrips. They are small insects that infest the underside of the leaves of citrus fruits and other plants, but in the case of citrus fruits also flowers and fruits. Their damage is represented by the stings, which cause discolored and necrotic areas. The Spinosad it can guarantee effective treatments and is allowed in organic farming.
  • Fruit fly. This dipteran affects many species, laying eggs inside the ripening fruits, and leading them to rot, through the tunnels dug by the larva. It is advisable to set up the capture of the fly with Tap Trap type traps, and to make treatments with Spinosad.

Growing grapefruits in pots

There cultivation of grapefruit in pots it is especially convenient in cold climate areas, such as all of northern Italy, because there it allows the whole plant to be wrapped in a non-woven hood in winter, considering that plant growth in pot is usually limited. For the same reason it will be useful to mulch the soil surface of the pot, which protects the roots from the cold. It is important not to chastise the growth of the plant too much by placing it in small pots, but still ensure it has a sufficient volume of soil. At the beginning, therefore, 40 cm in diameter of the container will be enough, then in the future we must remember to repot it in larger containers. The ideal substrate is a non-acidic soil, enriched with real earth and mature compost, to which natural fertilizers and regular irrigation are added.

Harvesting and use of fruits

There collection it must necessarily take place when the fruits are at a sufficient level of maturation, because this cannot continue after the harvest as happens with other fruits. In our area the grapefruit harvesting period is the winter, with differences according to the different varieties. For the right moment for harvesting, it is good to wait until they have dried from the night dew. Grapefruits are good to eat as they are or even squeezed, and are valuable sources of vitamin C.


Video: How to Grow Grapefruit Trees