Olive tree: all about planting, care & overwintering

Olive trees are the epitome of the Mediterranean. But with a little gardening skill, olive trees can grow here too. We show you how it is done.

With an olive tree (Olea europaea), you can bring the Mediterranean into your garden. Not only does the tree have impressive silvery shimmering leaves and a gnarled trunk, but also has added value: because after a few years you can even snack on the delicious fruits. But for the harvest to work, a little time must be invested in the care and choice of location. For this you will be rewarded with a healthy tree that can grow incredibly old. The oldest olive tree in the world is about 4000 years old. The next generations of amateur gardeners will benefit from your property for a long time to come.

Olive tree: a brief profile

Olive trees not only provide delicious fruit, but are also a treat for the eye. Even Vincent van Gogh raved about their characteristic appearance and the beautiful play of colours that is revealed when looking at the leaves. Here we have summarised the most important information about the olive tree:

• Botanical name: Olea europaea
• Genus: Olive tree (Olea)
• Family: Olive family (Oleaceae)
• Distribution area: Mediterranean area, Middle East, South Africa
• Life expectancy: Several hundred years
• Height of growth: Up to 20 m; in containers up to 2 m, slow growth
• Root system: Shallow rooter to 1 m depth; in very loose soil to 7 m depth
• Growth habit: Shrub or trunk
• Leaves: Evergreen; upper leaf surface: grey-green; lower leaf surface: silvery glossy
• Flower: Flowerheads of up to 40 white or yellow hermaphrodite flowers, formed on this year’s wood
• Flowering time: Temperature and light dependent, between April and June
• Soil: Well-drained garden soil mixed with sand & humus
• Location: Full sun and sheltered from wind
• Water requirement: Low
• Fertilisation: From 2 years every 2 weeks with liquid fertiliser
• Propagation: Via cuttings and seeds

Buying an olive tree: What to look for

As supply determines demand, you will find more and more garden centres, DIY stores and online plant mail order companies selling the Mediterranean plants. Because more and more plant lovers want to enjoy the Mediterranean ambience outside of their holidays in Spain or Italy. The prices range from discounter level to a hefty price tag. Unfortunately, the price usually says very little about the quality of the goods. That means only one thing: Keep your eyes open when buying olive trees. It is best to ask yourself the following questions before choosing a tree:

• Up to what temperature is the tree hardy?
• Oil olive or should it be harvested?
• Does the plant look healthy?

Do not trust seller who sells their product as completely hardy. This is simply a lie and screams incompetence. If you value quality and good advice, it is best to visit a specialty store for Mediterranean plants. The small additional price is definitely worth it.

Planting an olive tree

Since olive trees are not accustomed to our weather, and certainly not to our wet and cold winters, the right choice of location is even more important than the care of the frugal tree. As for watering and fertilising, the robust tree is fairly undemanding. But the wrong place means an early end for the tree, which can actually live several hundred years.

The right location

The distribution area of the olive tree is primarily the Mediterranean region. The gnarled plants can also be found in the Middle East and South Africa. It is therefore important to find a place in our somewhat cooler, domestic gardens that does justice to the warmth-loving southerners. The location of your olive tree should be chosen carefully, as the trees are hardy but need it to be as sunny and warm as possible. In addition, some varieties are extremely sensitive to wind. Therefore, the ideal location for olive trees is in the full sun, warm and protected from the wind.

The olive tree thrives best at an annual average temperature of 15 to 20 °C. Unfortunately, this does not work outdoors here. But the olive tree does not like being kept indoors only. Indoor olives do not grow so nicely and quickly drop their leaves. Therefore, the ideal year-around place for an olive tree is a heated winter garden. But a sheltered spot in the garden, on the balcony or terrace is also gratefully accepted in summer.

In winter, however, the trees need to move to protected winter quarters or receive proper winter protection. If, despite the winter difficulties, you decide to plant them, bear in mind that olives can be up to 5 metres in diameter. This means both the crown and the roots. So keep a good distance from the next woody plant, so that the plants do not get in each other’s way.

Note: Underplanting with thyme and rosemary is not only a skilful finishing touch for a Mediterranean-style garden, but also loosens and protects the soil in addition.

Planting an olive tree in a pot or in a bed?

Olive trees are used to the warm, dry weather of maritime areas. Planting in our climes is therefore only possible to a limited extent with robust and cold-tolerant varieties and is associated with problems and risks.

It is usually too wet and cold for the plants in winter, as they are only winter-hardy to a limited extent. It is usually only in areas with a warmer microclimate that it is suitable for planting outside, and even here, proper winter protection is needed. It is safer and more convenient to cultivate your olive in a tub. This can simply be moved in winter to a light location protected from frost and rain. Here you will find tips and tricks for successfully planting olive trees in pots.

Olive tree: the right soil

When it comes to soil, the saplings are more undemanding than in terms of location. After all, they are not exactly spoiled in their main growing area, Spain. It should just be reasonably loose and permeable.

When planting, just use garden soil, which you mix with sand and humus. In a pinch, potting soil also does the job. Soil permeability determines the subsequent root growth of the plants. In very loose soil, the roots can reach up to 7 metres deep into the earth. Otherwise, olives are flat-rooted. Most of the roots reach a maximum depth of 1 metre. That is why olive trees are so well suited as a container plant. In any case, make sure that the soil is well permeable to water. Waterlogging is not tolerated well at all.

Caring for your olive tree: watering, fertilising etc.

While location comes to the fore when it comes to making sure your olive tree thrives, you can avoid diseases and pests with the right care. Too much wetness in particular can quickly become a big problem.

Watering an olive tree

An olive tree can cope with periods of drought and hot temperatures. Therefore, planted in the garden, they usually do not need watering at all. With their long roots, the trees reach deep into the earth to get the water they need. Potted plants, on the other hand, need to be watered regularly. However, the plants do not tolerate waterlogging. Water when the surface of the soil has dried out superficial. In between, the whole tree can be sprayed with a water sprayer.

Fertilising a olive trees

For young plants, fertilisation should be very sparing. From the age of 2 years in the summer fertilise every 2 weeks with a little liquid fertiliser in the water for watering. Since the trees can be very sensitive to overfertilisation, use of a natural fertiliser is recommended. This has a slow-release effect, reducing the risk of over-fertilisation. Pay particular attention to a sufficient supply of potassium in planted trees, which makes the plants more resistant to cold. Mix eggshells, potash or bone meal into the soil when planting, or mulch with comfrey or bracken. For more information on fertilising olive trees, see our special article. A liquid fertiliser such as our Plantura Liquid Citrus Food, which is simply administered via the irrigation water, is excellent.

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Repotting an olive tree

Olive trees are very leisurely in terms of growth, but eventually even their old pot becomes too small. Repot your olive tree no later than when the first roots start to sprout from the pot’s drainage hole. On the one hand, the roots then have no more room to grow, and on the other hand, the water drainage becomes clogged and there is an increased risk of waterlogging. For optimal growth, do not wait that long. To do this, repot your olive tree regularly every 2 to 3 years. Simply detach the olive tree from its old pot and treat your olive to a pot about 4 inches larger with fresh soil. The exact procedure and other useful info on repotting olive trees can be found here.

Pruning olive trees

Olive trees can be grown into impressive bonsais even by beginners with a few judicious prunings. Minor pruning can be done throughout the year. Otherwise, cuts can be made in early spring, when the tree has gained a lot of strength from the winter dormancy. A distinction is made here between two types of pruning:

• Pruning: overly long shoots are shortened so that the outer crown remains in shape
• Inner crown pruning: in the case of crossing shoots, the weaker shoot is removed

Pruning will not only bring your olive tree into shape. It also ensures that all the leaves get enough sun. In addition, you should remove diseased or dead plant parts throughout the year. This will maintain the health of your olive tree. Detailed instructions for optimal pruning of olive trees can be found here.

Overwintering an olive tree

Olive trees are only conditionally hardy. Our cold and wet winters are just too much for plants adapted to the Mediterranean sun and a dry climate. Therefore, in order for you to still feel like you are on holiday in your garden or on the balcony, your olive tree must be stored properly in winter. For planted specimens, wrap the trunk and crown with winter fleece and cover the root disc with a protective layer of leaves, brushwood, mulch or conifer branches. Potted olives should be kept in a bright, cool but frost-free winter area.

Propagating olive trees

Olive trees are not exactly cheap. But like any plant, the olive tree can be self-propagated with the right know-how. This works out perfectly via seeds and cuttings. Whichever option you choose, for the successful propagation of olive trees depends on cosy warm temperatures.

Growing an olive tree from seed

Cultivation from seed is possible, but by no means always successful. If you still want to risk growing your own olive tree from seed, seeds from the shop or those from fresh, fully ripe fruit are suitable for this purpose. You cannot use the pits of pickled or otherwise processed olives for this purpose. Unfortunately, these are no longer germinable. Even whole fruits cannot simply be stuck into the ground. Remove the pulp beforehand and soak the stone in warm water for 24 hours. Only then does the seed coat become permeable to water and germination can begin. For even better water absorption, you can lightly roughen the stone with sandpaper before planting. After pre-treatment, you can start sowing.

• Fill a small pot with growing soil
• Put the stone about 1 cm deep in a pot with potting soil
• Use a water sprayer to keep the soil with the stone moist
• Location: Bright, at least 20 °C
• Germination time: A few weeks

Propagating an olive tree by cuttings

Propagation via cuttings should be the method of choice, especially for the inexperienced, because it is easy to perform and promises a higher success rate than propagation via seed. For this, choose a young, unwooded shoot if possible. Once you have selected a healthy candidate, the procedure is as follows:

• Cut the cutting to a length of about 5 to 10 cm
• The cut is set as obliquely as possible
• Small pot is filled with potting soil
• The lower leaves of the cutting are removed
• Cuttings are inserted 1 to 2 cm into the soil and the soil is lightly pressed down all around
• Water lightly
• Location: Bright and warm, e.g. windowsill
• Ideal temperature: 20 – 25 °C
• Keep substrate moist but not wet
• The cutting has rooted when the first new leaves develop

Harvesting olives

Olive trees bloom for the first time after 7-8 years. But also only if the location and care are right. The years of work are then rewarded with delicious olives. If you plan to harvest olives, it is best to use a self-pollinated, hardy variety. Cross-pollinated varieties need an additional second tree so that the flowers develop into something nutritious. However, even with self-pollinators, a second tree nearby has positive effects on crop yield.

Note: Trees from the nursery are usually between 3 and 4 years old.

The timing of the harvest is difficult to determine by the calendar. It depends on the time of flowering. However, this does not take place at a specific time of the year, but depends on local light and temperature conditions. In our climate zone, the flowers usually appear from April to the end of June. There will be very many flowers if you make sure that the plant is not exposed to drought stress or nutrient deficiencies before flowering. After pollination of the flowers, fruit formation occurs. This can extend into the autumn or even winter. Harvesting can be done when the following applies to the fruit:

• Colour change from green to red-purple or black (the darker, the milder the flavour)
• Flesh yields to pressure

Even the still unripe green fruits can be harvested. However, these must be debittered by pickling prior to consumption. Do not be upset if the first harvest turns out on the small side. The maximum yield is provided by the saplings only at an age of between 50 and 100 years.

The olive tree is not the only plant that can spread Mediterranean flair in the garden. In our article you will find more plants for a Mediterranean garden.