Olive Trees - Olea Europaea

Olea europaea. Copyright: Balcony Garden Web.

Contents

1. Top Tips
2. Location, Water, Humidity & Fertilisation
3. Common Issues
4. Origins, Temperature, Propagation, Repotting & Toxicity.

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Top Tips & Info

• Care Difficulty - Moderate
• Firstly, make sure your Olive Tree is sat in a location that offers the widest angle of natural light possible. In basic terms, we recommend keeping your specimen in a semi-shaded windowsill, that offers a few hours of either morning or evening sunlight.
• Due to the species' tolerance to cooler temperatures, never worry too much about cold spells during the autumn and winter months.
• Olive Trees prefer to be kept on the drier side to life. Instead of giving the plant little and often waters, consider pouring a large volume of water into the soil at once, while allowing the excess moisture to drain freely from the pot. Then, allow the top half of the soil in between waters to ensure the plant can rest before becoming wet again.
• Whilst using a nitrogen-rich fertiliser (an Olive-labelled or Houseplant feed, etc.), supplement the soil every three to four watering during the spring and summer, before reducing this to every sixth for the rest of the year.
• Repot every three to four years during the spring, using a 'Cactus & Succulent' labelled potting mix.
• Keep an eye out for Spider Mites, Mealybugs & Scale that'll hide in the plant's cubbyholes, including the leaves, juvenile stems and newly wooded bark. 

Location & Light - 🔸🔸🔸

Olive Trees are best suited in a bright location that boasts higher temperatures in the spring and summer. The warmth and light from the sun will considerably increase the overall health, as dark rooms with near-constant temperatures all year round will stunt the specimen's growth. A few hours of either morning or evening sunlight is highly beneficial for the plant, so remember to place yours in an east or west-facing windowsill.

If you have recently bought your Olive Tree from an indoor plant retailer, it can be trained to tolerate harsher levels of sunlight than most houseplants, by gently increasing the number of hours in the sun over the oncoming month. This process is best done from autumn to mid-spring, whilst the rays are at their weakest. Each week, increase the amount of light by an hour, starting with just an hour of morning sunlight to gain its momentum. The plant will slowly decrease the production of chlorophyll, which in turn will reduce the risk of bleaching and sun-scorch. Remember to keep the specimen well hydrated during this period, and always abort the experiment if it shows signs of sun-scorch. The maximum amount of sunlight for this plant is around six hours a day, but is best in daily exposures of around 3 - 5 hours. 

Water - 🔸

The ukhouseplants saying of 'drenches between droughts' strongly applies to Olive Trees. Not only will continuous soil moisture stress their root systems, but it'll also increase the risk of 'root rot' which essentially will destroy the plant from the bottom up. Allow the top half of the soil to thoroughly dry out in between waters in the growing period, reducing this further in the autumn and winter. Always pour enough water through the soil to allow any excess to drip from the drainage holes below, which in turn results in a sufficiently hydrated plant. Under-watering symptoms include stunted growth, a gap forming between the soil and inner side of the pot, and crisping or yellowing leaves. These issues are usually caused by too much light/heat or forgetfulness, so always be cautious for any risk of extreme dehydration. Remember, the brighter the location, the more watering you'll need to do. Over-watering symptoms include a weakened or rotten stem, no new growth, yellowing lower leaves and eventual plant death. The differences between under and over-watering can be very similar, with a rotten root ball and water-retentive soil mix being the obvious difference.

Humidity -

This is not a necessity; however, a quick hose down from time to time will hydrate the leaves and wash away dust or potential pests.

Fertilisation - 🔸

Fertilise every three or four waters during the growing period, and every sixth hydration in the autumn & winter to reinforce a dormancy period. Although a 'Houseplant' fertiliser will still do the job, we'd recommend using a specific 'Olive Tree' labelled feed as it'll support the vital thirteen nutrients that this species will need to grow. Regular feeding is paramount for a successful Olive Tree to flourish, so be sure to keep a tally of when you plant to feed it.

Common Issues with Olive Trees

Root rot is a common issue with Indoor Olive Trees sat in too moist or waterlogged soil for long periods. Symptoms include rapidly yellowing leaves, stunted growth and an overly heavy soil mix. Take the plant out of the pot and inspect health below the soil line. If the roots sport a yellow tinge, you're good to go, but if they're brown or mushy, and can be easily pulled from the soil, action must be taken immediately. More information about addressing root rot can be found on this link.

Curled leaves and dried brown edges are the result of too little water and over-exposure to the sun. Although Olive Trees can naturally do well in sun-filled locations, those that haven't acclimatised to the harsh rays will show signs of sun-scorch and environmental shock. Prolonged exposure will significantly speed the process of dehydration, so consider transplantation into a bigger pot in the spring to wrap the roots around moister soil. Reduce the daily hours spent in the sun whilst keeping in mid environmental shock, whereby a new location is greatly different compared to the previous. Maintain a partially sunlit location with only a limited amount of sun per day - preferably in the morning. 

Directly pinpointing yellow leaves is rather hard due to the many different issues that could be at fault. Problems include watering-related abuse, too much or too little light, and fertilisation issues. If you'd like to speak to ukhouseplants in regards to this issue, don't be afraid to book a 1-to-1 call to help guide you through the step-by-step process!

Mould or mushrooms developing on the soil means two things - too little light and over-watering. Despite the harmlessness, it'll prove unsightly to most gardeners and is therefore removed once known. To remove, replace the top two inches of the soil for a fresh batch of 'Cactus & Succulent' compost. Either increase the amount of light received (no direct sunlight for the first few weeks to prevent environmental shock) or decrease the frequency of waters slightly. If the mould is accompanied by yellowing lower leaves, you may also have a case of root rot.

A lack of flowers is due to immaturity. It can take many, many years for a specimen to reliably flower and produce fruit, so it'll be a case of 'wait and see'. If you're truly interested in home-grown Olives, try growing an outdoor specimen that's at least four years old with a wooded stem!

Origins

Olea europaea was first formally described back in 1753 by Carl Linnaeus, in his work, 'Species Plantarum'. The word, Olive, comes from the Latin for ŏlīva which, in turn, comes from the Ancient Greek equivalent of ἐλαία. 

The Distribution of Olea europaea.

Temperature

-2° - 40℃   (28° - 104℉)
H3  (Hardiness Zone 7)  - Can be grown outdoors most of the year whilst the nighttime temperatures are above 5℃  (40℉),  but is equally fine to remain indoors, too. If you decide to bring this plant outdoors, never allow it to endure more than an hour of direct sunlight a day as it may result in sun-scorch. Regularly keep an eye out for pests, especially when re-introducing it back indoors. Note: We'd recommend keeping yours outside during the period of late spring to late summer to further improve and revitalise the health of your Olive Tree!

Spread

Although the overall size can be up to 7m in height and 4m in width, you're most likely to see an ultimate height of around 2.2m when grown in an indoor setting. The ultimate height will take between 6 - 9 years to achieve when repotted every few years.

Pruning & Maintenance

You can prune and shape your indoor Olive Tree once a year using a clean pair of secateurs or sharp scissors. Although it isn't wise to cut directly through the leaf tissue, accidental moments where the individual leaf is sliced halfway off won't cause any ill health to the specimen. We'd recommend pruning the smaller branches by around a quarter every year, during the months of late spring before the main growth takes off. An annual prune is vital to maintain a well-balanced, vibrant looking specimen all year round. 

Propagation

Via Seed or Stem Cuttings.

Seeds (Easy to Moderate) - This method of propagation is by far the most enjoyable of the two stated below. The best soil to use is a 'Cactus & Succulent' labelled potting mix; however, multipurpose compost with added perlite and sand is perfectly fine. Set the seeds around 1cm deep (½ inch), resisting the temptation to compact it. Maintain evenly moist soil and allow the excess water to freely drain from the pot's base to prevent water-logged conditions. The ideal location for successful germination is in a bright, indirect setting with temperatures around 25℃ (77℉) with bottom-heat. Keep the pot in a transparent bag to provide a stable environment, along with longer-lasting soil moisture. Germination may take between two to eight weeks to occur, so don't discard any unsuccessful seeds until this threshold has been surpassed. Remove the bag once the seedlings produce their third leaf and split them into their own 5cm (2 inch) pots after another month.

Stem Cuttings (Easy to Moderate) - Lateral stems (smaller sideward branches) that are around 10cm (4 inches) in height and obtain healthy, damage-free leaves are the best to propagate. To avoid making a mess of the serrations, use a clean pair of scissors and cut 10cm down from the branch's tip, dipping the wound in water and then into rooting hormone to speed the propagation. We recommend pruning off the lower, older half of the leaves to deter moisture-loss which is a common issue when a plant has been severed from its water source (roots). Use a 'Cactus & Succulent' labelled potting mix with a pot that has adequate drainage holes to avert the risk of over-watering. Provide a bright, warm setting of around 20℃ (66℉) with relatively moist soil, but always be sure to allow the top half to dry out in between waters. You'll know if propagation is successful as the leaves will stay green and firm, along with small roots developing from the callous (dried wound) within the soil. New foliar growth will emerge from the nodes after around twelve weeks, but it may take longer if the conditions aren't optimal. After a month of solid new leaf growth, transplant into a slightly bigger pot and treat it like a mature specimen with the care tips provided above.

Flowers

Mature Olive Trees of around 4 - 5 years will flower from early to late spring to summer, producing liquorice-scented yellow flowers across the foliage. Each inflorescence can last up to ten days, with the overall flowering process spread across several weeks.

Repotting

Repot every three to four years in the spring using a 'Cactus & Succulent' labelled potting mix and the next sized pot with adequate drainage. Plastic or terracotta pots are fine, but we'd recommend using the latter for aesthetic reasons. Indoor Olive Trees are far better potbound for several years due to the heightened risk of root rot and repotting-issues (like transplant shock) - so only repot if you feel it's wholly necessary.

Hydrate the plant 24hrs before tinkering with the roots to prevent the risk of transplant shock. For those situated in a darker location, introduce extra amounts of perlite and grit into the lower portion of the new soil to downplay over-watering risks. Click here for a detailed step-by-step guide on transplantation, or via this link to learn about repotting with root rot.

Book a 1-to-1 video call with Joe Bagley if you'd like a personal guide to repotting your houseplant. This will include recommending the right branded-compost and pot size, followed by a live video call whilst you transplant the specimen for step-by-step guidance and answer any further questions!

Pests & Diseases

Keep an eye out for mealybugs, spider mites, scale, thrips, whitefly & root mealybugs that'll locate themselves in the cubbyholes and undersides of the leaves, with the exception of the latter in soil. Common diseases associated with Olive Trees are root rot, canker, scab, leaf-spot disease, botrytis, rust, powdery mildew & southern blight - click here to learn more about these issues.

Toxicity

This plant is classified as non-poisonous. If large parts or qualities of the plants are eaten, vomiting, nausea and a loss of appetite may occur.

Retail Locations

Some Garden Centres, DIY Stores & Online Stores.

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