Citrus trees are the ideal present for the plant-lover or the cook. They will thrive in a cool conservatory or light porch, or even a sunny window sill. In the summer months, citrus will love it outside in the garden - and if you are lucky enough to live in a part of the UK with mild winters then you can leave some of the larger, hardier varieties in the garden all year round.
Citrus trees have been grown in the UK for hundreds of years and in the right spot are easy and really rewarding plants.
They need plenty of sunlight and somewhere cool but not cold or frosty
In the UK that means they do need to be indoors in the winter to protect them from frost.
In the summer they will be happiest outside on a sheltered patio but they will also do well on a windowsill or in a bright room or conservatory.
Indoors try to keep your plant away from any radiators, underfloor heating or draughts and if on a windowsill keep the leaves from touching the glass.
Calamondins, kumquats, Mexican limes, grapefruits and orange trees should all be kept above 8C so can only go outside for the warmest months of the year.
Lemon trees and particularly the mature lemon trees can take cooler temperatures right down to 1 or 2C and can go outside as soon as the night time temperature is above freezing. (They will even survive a mild frost if you get caught out).
We always err on the side of caution when exposing plants to cold temperatures but we have had many reports from the South West and London of Lemon trees doing well outside when trained up walls or kept in pots on sheltered patios.
If and when you do move your plant outside do be aware that a sudden change in light levels can cause 'sunburn'. To avoid this place your plant in a partially shaded spot for a few days before moving into full sun or move it outside for a few hours a day until it has adjusted to its new position. Too dramatic a change in light level can lead to blanching of the leaves and some leaf loss but over time your plant will recover and put on new growth.
Getting the watering right is crucial with citrus, the trick is to water only when the soil is dry to the touch and then to water heavily from the top of the pot. You should expect the amount of water your tree uses to change quite dramatically from summer to winter and according to the weather.
How often you will need to water depends on: Air temperature, wind, location (light/dark situation), the size of your plant in relation to its pot & the type of soil
Both underwatering and overwatering lead to leaf loss and can eventually kill your plant.
Water at least 20% of the volume of the pot each time
so 200ml for a small calamondin in a 1L pot,
1L for a large lemon tree in a 5 litre pot.
When the surface of the soil dries out on top, remove the plastic pot from any pot cover or basket and water the plant heavily until the water runs freely through the soil and out of the holes in the bottom of the plastic pot. You might find it easiest to do this in a sink or outside. Don’t f orget to throw the excess water away and never let the pot sit in a pool of water.
As with most plants, citrus trees will absorb water better and more efficiently if watered in the cool of the morning or evening rather than in the middle of the day. Avoid splashing the leaves with water generally but particularly in the middle of a sunny day.
Things that will affect how much water your plant needs
The higher the air temperature the more often your citrus plant should be watered, because it will be evapotranspiring more. (or ‘breathing’ more)
The more wind or draft around your citrus plant the more water it will be using, so it will need to be watered more often.
If your citrus plant is very big in relation to the size of the pot, then the amount of water the pot will hold will not be enough to last it very long, so it will have to be watered very frequently, and thus it is more likely to dry out. In general the plant should be 2 times the height of the pot. If it is any bigger, the watering becomes more difficult, and you should pot your plant into a bigger pot (see Repotting)
In a hot summer plants can need watering up to twice a day when in a small pot but in the winter months this might drop right down to once every 2-3 weeks. It is therefore important to be adapt your watering routine as the seasons change, be wary of underwatering in the spring and overwatering in the autumn.
Citrus plants generally like a well-drained slightly acidic soil but they do grow well in a variety of soils and more dense clay soils taking longer to drain water through than bark based compost.
How do I know if my plant needs watering?
If the top few centimetres of the soil becomes dry to the touch, then it is time to water your plant.
By observing the leaves, you can also tell if the plant needs water. If the leaves start to droop, and wilt or loose their normal shade of green, as pictured below then your plant is already showing the first signs of stress and should be watered straight away.
After watering you plant, it is a good idea to lift it up and feel the weight of it in your hand. You can then use that as a reference to judge whether the plant needs watering in the future. After a while you will begin to be able to judge quite accurately using this method.
Sudden and dramatic leaf loss is almost always due to underwatering so watch carefully to catch your plant before this stage.
Symptoms of Overwatering
You should only water when the top of the soil is actually dry to the touch. Most problems come not from watering too much but watering too often. If you consistently overwater your plant, you will starve the roots of oxygen, and prevent them from functioning properly. They can start dropping their leaves a few at a time at this stage and if it continues can lead to root rot and eventually the death of the plant.
Your citrus plant will survive happily indoors in centrally heated houses as long as it is not too dry.
There is a lot of conflicting advice on misting vs not misting citrus trees. We don't mist our trees in the nursery because it is normally fairly damp. We recommend that you only mist your plants if they are in a very dry warm room or if you find that the flowers are not setting fruits - otherwise you can increase the chance of developing fungal diseases.
If you do have a particularly warm house and you do opt to wet the leaves of your plant then it is best to do this either in the early morning or evening. In full sun, water on the leaves of your plant can act as a magnifying glass and scorch the foliage.
If your plant is outside it will adapt to the moister conditions and higher light levels and will cope surprisingly well with wet conditions as long as the roots are able to drain properly.
If it has been particularly hot and you are struggling to keep your plant well watered you can splash the leaves in the evening when you are watering to cool it down and raise the humidity but avoid doing this in the middle of the day when the sun can scorch the leaves.
In extremely damp conditions for example if you overwinter your citrus in a greenhouse or damp conservatory then it might be worth opening the windows in the middle of the day.
Indoors and out spent flowers and dead fruits should be removed regularly to keep the tree looking neat and to avoid fungal problems.
When your Plants4Presents citrus tree arrives it will be well fertilized and should not need any additional feed for the first 4 weeks. After 4 weeks it is a good idea to start using the relevant citrus feed to keep your plant healthy.
Most plants including citrus trees benefit from additional Nitrogen, Phosphorus and Potassium and general purpose and houseplant fertilizers contain these in various ratios. Citrus trees however also need high levels of trace elements to keep them including Iron, Calcium, Magnesium, Boron, Copper and Zinc to keep their leaves and fruits healthy. General house plant feeds and tomato feeds etc contain Nitrogen, Phosphorus and Potassium (NPK) but not all the required trace elements.
You can buy citrus feed (winter and summer feed) directly from our web site ...click here and we will send your citrus feed to you by post or by phone on 0845 226 8026
Made to our own balanced formula this is what we use and recommend although of course there are other options available at your local garden centre. If using these do check that they have a summer and winter feed and that they contain all the trace elements listed above.
Summer Citrus feed is used from April to October and contains more nitrogen to help your plant put on fresh leaves and summer growth.
Winter Citrus Feed contains proportionately more Phosphorus and Potassium to help your plant set and develop fruits.
However if you run out, either feed is better than none.
In addition to feeding regularly it is a good idea to top up your citrus tree compost every spring and to repot it at least every other spring to give it a fresh boost of nutrients.
When to feed?
Use fertilizer every other time you water your plants, in the growing period (when the new shoots appear).
Outside the growing period, you will find that you are watering less often so every other watering might be once ever 3 weeks which is fine. The fruits will develop using the energy that has been stored up in the leaves and stems of the plants throughout the growing period.
When should you repot?
Citrus plants need to be periodically repotted to maintain a healthy plant - once a year or once every 2 years for trees up to 6ft in height. For trees over 6ft you can usually just top up the compost once a year and repot every 3 or 4 years.
Normally our trees will be sent in a suitable pot and you won’t need to think about repotting f or at least six months. However if you are not sure, a good rule of thumb is if your citrus plant is m ore than 2 and a half times the height of the pot, then it is ready to be repotted.
Potting should ideally take place in the spring or early summer when the plant begins to show signs that it is growing. Sometimes you might decide to repot your tree in the summer because your plant has grown on a lot or because you are struggling to keep up with the watering. However avoid potting up your plant in the late Autumn or winter unless there is a good reason as it will not be growing and the roots won’t move into the new soil.
What kind of soil?
The size of the new pot should be a large enough to allow a few centimetres of new soil around the edge of the old rootball. It can be repotted in any well drained mixture that is slightly acid. Probably the easiest solution is to buy a citrus compost in a garden centre but you can also use top soil from the garden or 50:50 a mixture of top soil and ericaceous compost with a handful of sharp sand/grit/stones for extra drainage. The ideal pH is 5 to 5.5.
Guidance on Repotting
Remove the old pot (Turn the plant upside down and hold it soil in with one hand and pull the pot off with the other) If the roots are tightly knotted together, gently pull them away from each other so that they will then be able to move out into the new soil. Put a small amount of soil into the bottom of the new pot, lower the plant into the pot and fill up around the edges, compacting the soil gently with your fingers to make sure that there are no air gaps around the edge. Water the plant th oroughly a few times, to make sure the soil is wet.
Older citrus plants can be repotted into the same pot if needed. In this case you should cut away some of the root with a knife or secateurs (approximately a few centimetres) and remove as much of the old soil with your fingers as possible before repotting as above with fresh soil.
The trickiest thing with citrus trees is getting the watering right. Overwatering and underwatering are by far the most common cause of problems in citrus trees.
Overwatering is most common in the winter months or at the change of the seasons from summer to autumn and results in steady leaf drop, root disease and/or lightening of the leaves. Dropped leaves are normally leathery to the touch but if you hold off and really dry the top of the soil out before watering again you should see a full recovery.
Underwatering Not watering frequently enough or not watering thoroughly enough to ensure that all the roots receive water can result in a sudden and dramatic leaf drop. It is most common in the summer and in the spring when the amount of water your plant needs suddenly increases. If you have slipped up and allowed your plant to dry out completely don't despair we have seen even some of the most bare and forlorn specimens come back to life with the right care.
Overfeeding Generally it is much more common to under rather than other feed so as long as you are following the recommended dose you shouldn’t need to worry about over feeding. In extreme cases using more than the recommended rate of fertilizer can “burn” the roots, but this is rare.
Underfeeding Citrus trees are really quite greedy feeders and lack of nutrients leads to pale, sickly looking leaves and also a susceptibility to pests.
When the plant doesn’t have enough nitrogen and/or iron the leaves typically turn yellow and or mottled (view photo) Once this has happened you will need to feed regularly for some time to get the new leaves to come through green and healthy. Unfortunately once the leaves have got to this stage it is very difficult to return them to a healthy green and most people only get a partial recovery on the old leaves.
Sometimes a plant can struggle to absorb particular elements because the water is hard or the soil can become unbalanced over time leading to a lack of a particular trace elements. Eg a lack of calcium leads to yellow or yellow brown tips to the leaves
TOP TIP You can apply your citrus feed as a foliar feed to help get the nutrients directly to the affected leaves. Simply make it up at half strength and water the solution directly on to the leaves and new shoots. Be sure to do this in the morning or evening so that bright sunlight does not scorch the leaves.
Calamondin leaves curling indicates it is time for a watering
At this point a swift and thorough watering will normally save your plant from losing more than a handful of leaves.
If you find that despite a regular feeding regime the leaves are still coming through light in colour or mottled then you may have hard water and/or need an extra boost of nutrients – give us a call and we’ll be happy to advise.
Pruning citrus trees should generally be done at the end of the summer or in the spring after the first flush of growth. You are aiming to remove any particularly fast growing 'water shoots' and tidy up the overall appearance and bushiness of the tree. You should always use sharp seceteurs and diagonal cuts towards the centre of the tree to increase the bushiness and diagonal cuts away from the centre if it is getting too crowded and needs opening out.
Pruning is not necessary for producing fruit but it does help keep the plant in good shape and keep the branches strong enough to eventually hold the weight of the fruit. To encourage fruit production simply keep your tree in as light a spot as possible and keep up a regular (reduced in winter) watering regime.
Sometimes citrus trees are grown along supporting trelliswork to allow them to bear fruit younger and to form an attractive shape. Over time your plant will eventually outgrow these trellis work and can either be repotted and trained up a larger trellis or slowly trained into a stand alone tree.
In either case once the first crop of fruit has ripened and been harvested you should remove the clips from the outer branches so that they are allowed to spring free of the initial support. You can then either tie these in with clips/or twine to a larger trellis or support or start to train it to stand alone.
When removing the trellis work it is easiest to remove all the ties first then cut out the trellis work removing it in sections starting with the outermost sections first. Then if the plant feels at all unstable you can leave the central stem support for a little while longer whilst it stabilizers. (See illustrations on right).
Plants4Presents citrus trees are grafted plants sourced from reputable citrus growers in P ortugal, Italy and Spain and it is extremely rare for us to have any problems with fungal diseases or viruses. However like all plants, citrus trees are sometimes susceptible to pests and insects. Sometimes these crawl from one plant to another or sometimes they might fly in or arrive on peoples clothing. Checking your plant every few weeks for signs of trouble will allow you to spot and treat problems before they get hold.
Aphids - can attack the young shoots and flowers particularly in the Spring and Summer. Watch out for sticky residue on the leaves, green, brown, black or orange bugs on the shoots and/ or white specks on the tops of the leaves (these are the shed aphid skins dropping from above). A general purpose pest spray or even just a washing up liquid and water solution will keep these sap sucking greenfly at bay. It is rare f or them to get a good enough hold to do lasting damage to the plant but they can limit flower and theref ore fruit production
Caterpillars - like aphids these attack the flowers and young shoots. Butterflies lay their eggs in the flower buds and the baby caterpillars can do quite a lot of damage to the flowers and fruit crop if not caught early. A spray or simply removing all chrysalis and eggs by hand will solve the problem.
Scale insect - scale is not common but it is quite damaging. Keep an eye out for any stickiness and for round brown circles on the undersides and veins of the leaves, on the branches or fruit. They will slowly weaken the plant and should be treated immediately with a biological pest control or spray (we like S&B invigorator as it’s fairly organic but there are others available at your local garden centre). You can remove the visible round suckers with your fingernails or a flat knife which will help but the juvenile scales are invisible to the naked eye so a spray is the best way to clear your plant permanently.
Cotton Cushion Scale – this is a rare pest but we have seen one or two reports in recent years and it is worth spotting early. The big adult cushions don’t even look like insects but underneath they are breeding hundreds little suckers which will feed on all the goodness from your plant.
Mealy Bug - these white fluffy creatures are related to woodlouse. They live in the cracks and crevices of the branches and look like cotton wool or trapped fluff. If you do find them a specialist spray or biological pest control is the best way to treat them or in extreme cases methalayted spirits applied with a paint brush is an old gardeners tip that sounds harsh but works wonders.
Vine Weevil - adult vine weevil are up to 2cm long and leave jagged marks around the outside edges of the leaves they attack. However it is their larvae that do the most damage though, feeding on the roots of a wide range of house and garden plants and weakening them irreversibly. At the first sign of any trouble treat all your pots and houseplants with a nematode solution (See our sister site www.ladybirdplantcare.co.uk for more information on environmentally friendly pest control) and be vigilant for their return.
If you need any help identifying pests on one of our trees then please do get in touch. We can often diagnose the problem over the phone or for more unusual problems do send us photos by email or even send us leaf samples by post and we’ll have a look under the microscope. Once you know what you’re dealing with it’ is much easier to treat the problem and get your tree back on track.