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Friends of Mediterranean garden design advocate the cultivation of olive trees in pots because of the many advantages associated with it. The mobility of a pot allows you to enjoy the magic of the evergreen Olea europaea with its rustic, gnarled trunk north of the Alps. This green guide explains in detail how to properly grow a potted olive tree. From the ideal location to perfect watering and fertilizing to skilful pruning and the best possible overwintering, the care information extends from A-Z.
from spring to autumn
An olive tree is not suitable for a permanent stay in living and working rooms, entrance halls or temperate conservatories. The Mediterranean ornamental and fruit tree should benefit from unfiltered sunshine and fresh air, as long as it is not freezing. If the meteorologists predict in spring that the temperatures during the day and night will continuously exceed the 10 degree mark, the outdoor season for the olive tree begins. The following conditions are very good for an Olea europaea in a pot:
- Full to sunny location with at least 6 hours of sunshine per day
- Preferably on a south-facing balcony or terrace or in front of a warm south-facing wall
- Ideally a rain and wind protected location
The pronounced preference for direct sun does not imply that decorative olive leaves are immune to sunburn. The evergreen foliage immediately reacts to an abrupt change from the dark winter quarters to the blazing sun with yellowish-brown spots with dark borders. You can avoid this damage by prescribing a 10-day acclimatization phase for a potted olive tree in a partially shaded, sheltered location. After that, the container plant is perfectly prepared for full sun conditions with temperatures up to 40 °C.
When properly cultivating an olive tree in a pot, the substrate plays a key role. Because the limited capacity of a bucket significantly restricts deep and expansive root growth. This shortcoming should be compensated for by the quality of the potting soil so that the unspoilt icon of the Mediterranean meets the high expectations. You should ignore conventional potting soil with a high peat content. For growing olive trees in pots special substrates from the specialist trade because they are precisely matched to the special requirements of the deep rooter. As an alternative to purchasing expensive special olive tree soil, you can mix the substrate yourself. The following components should be included:
- Mature, medium-grain compost or bark humus (from your own garden or specialist shops)
- Clay garden soil, loose and humic
- Coconut or wood fibers as a peat substitute
- bentonite, lava granules, vermiculite or expanded clay
- Garden or algae lime
- Sand or fine-grained grit
The right mixing ratio is a lively topic of debate among olive gardeners. In the course of cultivation you will develop your own personal substrate recipe based on your experience. The following composition has emerged as suitable for beginners:
- Compost or bark humus - 4 parts
- ordinary garden soil - 4 parts
- Coconut or wood fibers (no peat) - 2 parts
- Bentonite, lava granules or other clay mineral - 1 part
- Lime - 1 part
- Sand - 1 part
The optimal pH value of olive tree soil is between 7 and 8. Acidic citrus plant soil is therefore unsuitable. A common misconception is that olive and lemon trees are Mediterranean plants that require acidic soil conditions. In fact, an Olea europaea in a pot asks for one calcareous Earth for vital and healthy growth. If in doubt, simply measure the pH value of the substrate mixture. Test sets are available in garden centers and hardware stores for a few euros. The application is usually based on coloring reactions and does not require any chemical knowledge.
with a sure instinct - that's how it works
Pot farming requires more frequent watering than planted olive trees. The sunnier and warmer the location, the faster the substrate dries out. Although the Mediterranean tree copes well with short-term drought, the soil should not dry out completely. The right water supply is aimed at a periodically moist substrate that dries up by at least a third in the meantime. How to properly water an olive tree in a pot:
- The best time is early in the morning when the cool root ball can tolerate cold tap water
- Before watering, use a finger test to determine whether the top third of the soil has dried
- Let normal, calcareous water run out of the can spout onto the root ball
When it comes to the water supply, act according to the rule of thumb: water the olive rarely, but then plentifully and thoroughly. After each watering, wait until the soil has dried noticeably again. If you are a beginner in skin care and do not want to rely on your instincts, you can use a moisture meter. This is a simple measuring stick that is inserted into the substrate. After a short time you can read off a scale whether the soil is wet, semi-dry or dry.
Tips for the perfect nutrient supply
One of the uncomplicated measures for caring for an olive in a pot is the supply of nutrients. How to fertilize an olive tree with gardening expertise:
- Add a liquid fertilizer to the irrigation water from April to September
- Recommended sodium-phosphorus-potassium formulation (NPK) 20+5+15
- Dosage and administration according to manufacturer's instructions
It is important to note that you do not add fertilizer-enriched irrigation water to the dried soil. Water before and after with clear water so that the salt concentration does not cause root damage.
when and how to do it right
When the winter dormancy is coming to an end, the time window opens for care and maintenance pruning. Garden shears or rose shears are sufficient for a young olive tree. In order to cut branches with a diameter of more than 3 centimeters on an older specimen, we recommend a handy folding saw. Between the beginning of February and the beginning of the fresh shoots, devote yourself to this pruning:
- Cut off dead branches and dead shoot tips
- Cut back branches protruding from the crown shape
- Set the scissors 3-5 millimeters away from a leaf bud
- Cut out shoots growing into the crown
- From two branches that are close together, prune the weaker one
In many Mediterranean gardens north of the Alps, olive gardeners often complain about one balding crown. Since olive trees primarily grow at the tips of the branches and put on new leaves, the inner crown is visibly aging. In this case, the expert care sees you taper cut before. By cutting all branches in half, but at least a third, you encourage the olive tree to sprout again from dormant eyes at the base. When pruning, make sure that at least 2 vegetation points remain on the shoot. You optimize the growth forecast by first repotting the olive tree in fresh substrate.
General conditions and care in brief
Do not plant a potted olive tree until nighttime temperatures approach -10°C. The longer the plant stays outdoors, the better it can cope with overwintering behind glass in the Central European climate. In regions with mild winters, such as wine-growing regions or on the Lower Rhine, most potted olives stay on the balcony and terrace until just before Christmas. In order to choose the ideal date, a minimum-maximum thermometer placed nearby provides precise information. How to overwinter an Olea europaea correctly:
- Ideal winter quarters: bright to sunny with a cool 0 °C to 5 °C
- Do not fertilize between the beginning of October and the end of March
- Water sparingly with normal tap water
- Ventilate regularly
A combination of lots of light and low temperatures offers an olive tree the best possible environment. An unheated winter garden, a bright, cool stairwell or the light-flooded, frost-free garage are well suited as winter quarters. However, if there is a lack of light, the olive sheds its evergreen leaves. But that is no cause for alarm. The crown sprouts happily again in spring, as soon as the tree can take its place on the balcony or patio again. By hanging a plant or daylight lamp above the crown and turning it on for at least 8 hours a day, you will prevent leaf shedding.
You should repot your olive at intervals of 2 to 3 years. This premise also applies if the tree has not yet completely rooted its pot. At least a change to fresh substrate is on the care program after this time. As long as there is at least 2 fingers of space between the root ball and the edge of the pot, you can use the previous pot again after thorough cleaning. When buying a new bucket, please make sure that there are one or more openings in the bottom than water drainage. How to skillfully repot an olive tree:
- The best time is in the spring before clearing between February and May
- Spread out an old blanket, curtain or foil
- Lay the olive tree on its side, grasp the root collar and slowly pot out
- Use a long knife to loosen the stuck root ball from the pot wall
- Shake off old substrate or remove with fingers
- Lay out a drainage of grit, pebbles or broken pottery on the bottom of the bucket
- To protect against silting, cover the drainage with an air and water-permeable fleece
Use a ruler to measure in advance how much potting soil needs to be filled in so that the root disc is 3 to 4 centimeters below the edge of the pot. Fill in the substrate and then press it down with both hands to avoid air pockets. Now position the root ball in the middle of the ground. While stabilizing the trunk with one hand, fill in the substrate with the other hand. Shake the root system from time to time so that the soil is distributed to all interstices. In the last step, press the substrate down again and then pour thoroughly until the first drops run out of the bottom opening. In the following 8 to 10 days, a repotted olive tree stays in a partially shaded location to regenerate.