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24 September 2014

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You are in: Lancashire > Nature > Features > Ask the gardener: Oranges, lemons and limes

lemons

Ask the gardener: Oranges, lemons and limes

Find out how to care for your citrus trees!

Warton's Bill Blackledge is one of the county's most popular and sought after gardeners.   If it's green and needs watering, Bill can tell you about it.  He has been answering BBC Radio Lancashire listeners' queries for over thirty years, which means he's been there nearly as long as the transmitter!

His knowledge is encyclopedic. After training at the under the then Ministry of Agriculture, Bill spent over twenty years at the Department of Biological and Environmental Services at Lancaster University.  Now, he's a regular course tutor at Alston Hall, Longridge and Lancaster Adult College.

For three decades, Bill has travelled the county with fellow judges as a regional judge for North West in Bloom.

So, whatever the problem, we like to think Bill can sort it out... at least that's the theory!

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Callie asks...

I'd like to buy a Lemon and a Lime tree from a specialist nursery, to make sure I get a really good quality tree. Can you recommend any stockists near Lancaster, or online? Many thanks

Bill replies...

If you go on line Callie you will be able to find a list of specialist growers of Citrus Fruits but there is also a number of Garden Centres/DIY Stores in Lancaster and the surrounding area which do sell Lemon and also Lime Trees and it would be worthwhile having a look around these Centres to compare prices.  With regard to cultivation techniques you will find answers to cultivation techniques on this web site.

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Philip Matthews asks...

I have sprayed my kumquat with pesticide but still have loads of caterpillars.

Bill replies...

Kumquat plants (Fortunella Japonica/Fortunella Margarita) Philip are very closely related to the Citrus Fruits and will produce thin skinned fruit which can be eaten straight from the plant.  With regard to the caterpillars on your plant we are dealing with a fruit crop and it is important that if you are spraying your plant you use one of the safe contact insecticides.  If you just have one small plant, it might be worth looking over the leaves to handpick the caterpillars off.  There are a number of insecticides on the market and available in both Garden Centres and DIY Stores which can be used on certain edible fruits but it is important to check the instructions before use.  

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Sue Thompson asks...

I have a lemon tree in a pot and since bringing it indoors for the winter, something is eating the leaves! I have looked in vain for an insect - I may have found a Mealy Bug - it looked like a larva wrapped in a web but do these eat the leaves.  There are some quite large areas that have been 'munched' away by something.

Bill replies...

One of the problems Sue when you bring trees such as Lemon Trees indoors during the winter months they do become prone to attacks by a range of pests.  You say that you have found what looks like a larva wrapped in a web but this is not as you suggest a Mealy Bug which are tiny insects encased in a substance similar to cotton wool.  You do need to remove the larva/caterpiller and the web which it is encased as these will eat the leaves of your plant. Also you say that quite a number of the leaves have been eaten away and this could have been quite easily been caused by a Weevil and the most troublesome of these is the Black Vine Weevil which is approximately half an inch in length, black in colour and has a pointed nose.  These Weevils are nocturnal and you will need to check late evening to see if there are any of these Weevils present.  It is also worth checking to see if there are any pinkish white grubs in the soil and these are the grubs of the Vine Weevil and they will eat the roots of your tree.  If you do find any of these Weevils please contact me again through BBC Radio Lancashire and I will give you further advice re control.

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John Lipscomb asks...

I had an olive tree in my greenhouse which became diseased last year with a black sticky substance and there were very small black beetles motionless on the stems and leaves.  I removed it from the greenhouse but now 4 months on my lemon tree in the same greenhouse is suffering from the same disease.  Do you have any idea what the problem could be and is there anything I can do to cure the problem to stop it spreading to my other trees in the greenhouse?

Bill replies...

The black sticky substance on the leaves of your Olive Tree John is, I am sure, sooty mould which is a mould that survives and grows on the sugary glucose which has been secreted by aphids and also scale insects and, what you will need to do is with warm soapy water wash this sticky substance off the leaves.  You will also need to look closely on the under side of the leaves of your Olive and Lemon Trees to see if there are any small scale insects present.  If there are scale insects present you will need to spray with an insecticide but, if you are going to use the Olive and Lemon fruits you will only be able to use a contact safer insecticide. If you have no intention of using the fruits you could use a systemic insecticide which would be far more affective.  With regard to the black beetles which stay motionless on the stems and leaves these could quite easily be Black Vine Weevil adults and you will need to remove these from tree and you will also need to check your soil to see if there are any white pinkish grubs as these are the grubs of the Vine Weevil and will eat the roots of your trees.  There are websites available with more detailed advice/photographs on Vine Weevil.  If you feel you do have problems with Vine Weevil please email BBC Radio Lancashire again I would will give you further advice.

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Julie Brown asks...

I have a indoor lemon tree and it had fruit on when I was bought it for Christmas. It now has 3 open and 2 closed flowers but the new leaves are much larger and lighter then the ones on when I bought it. When should I repot and would it harm it to repot while in flower? Thank you for any advice you can give me.

Bill replies...

Lemon Trees Julie like other citrus trees do not like their roots to be disturbed and only need to be repotted when pot bound and this can be carried out late springtime. They only need to be transplanted into a slightly larger pot - approximately two inches larger - and it is important to always use a soil base compost such as John Innes No 2 or 3.  It is important during the summer months to place your Lemon Tree outdoors in a sheltered spot.  Lemon Trees do continue growing throughout the twelve month period and you will need to feed once a week during the summer months and approximately two to three weeks during the winter period.  Do try to keep your tree outside as long as possible during the summer months but you will need to take indoors during the cold winter period. Also it is important not to keep your tree in too warm a temperature - ten to twelve degrees will be fine.  With regard to feeding there are specialist citrus food fertilisers which you can use.

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Mark asks...

I have a Calamundine orange tree about 2 feet tall which I would like to plant in my front lawn. The lawn is south to south west facing. I understand that Citrus trees are not very frost hardy so is there anything I can do to protect it during the winter months?

Bill replies...

Calamundine Orange Trees Mark do have similarities to other citrus fruit trees in that they are outdoor container plants but, they do need be taken indoors during the winter period and during the summer months need to be placed in a dappled but, slightly shady position.  Calamundines do not like to be placed in full sun and thrive in temperatures approximately twelve to fifteen degrees centigrade over the summer period.  During the winter period temperatures of between seven to ten centigrade are ideal.  With regard to planting your Calamundine outside within your lawn I am afraid that this too risky and you would be far better planting an ornamental flowering Crab Tree such as Golden Hornet or John Downey in your lawn.

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Jane Atkinson asks...

I have had several citrus trees in my conservatory and lost them through over watering, pests etc. not wanting to give up I bought a very healthy Mandarino at the end of November which has several fruit on it. Now the leaves are dropping constantly and the wood from which they have dropped seems to be dying from the tips in towards the plants. The tree is 2 foot tall and there are no draughts I spray the leaves and water occasionally with already boiled water. The temperature in the day is around 19 and probably 11 at night. the conservatory has plenty of light due to it being a glass roof. 

Bill replies...

Citrus trees can be temperamental Jane and listed below are a number of cultivation points which I hope you will find helpful.

Citrus are outdoor container plants and only need to be taken indoors (in a cool conservatory) during the winter months.  They do not like much root disturbance and, when they do need repotting I would use a soil base compost - John Innes No 2/3 - and they like to have a pH of 6.5 to 7.  With regard to temperatures it is important during the winter months to have a temperature of not less than seven to eight degrees C (45 degrees F) and the temperature should not rise above 12/13 C.  High temperatures cause the leaves to shrivel and the trees will deteriorate rapidly.  On watering it is important to water with tepid water, watering with cold water causes the leaves to curl.  You will find that Citrus Trees will need feeding throughout the year - once a week from April to October and approximately once every two to three weeks during the winter period.  You mention that your Citrus Trees are loosing leaves constantly but, I would not worry too much about this, they are deciduous trees and you will find that they will drop a certain amount of leaves throughout the year but, again, this leaf drop can be caused by too high temperatures.  The golden rule is to keep your trees outside as long as possible over the summer period in a cool slightly shaded position - away from direct sunlight - and only need to be taken indoors over the winter period.

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Anne Finestein asks...

I have a huge lime tree, much higher than the roof top of my double storey house. It has aphids causing damage to the house, drive, and cars a dreadful sticky black substance.  Can this be cured and if so how?

Bill replies...

I am afraid Anne that Lime Trees are prone to attacks from aphids and other insects and it is the glucose which is secreted by the aphids which is causing damage to your drive and cars.  With it being such a large tree it is going to be impossible to spray with an insecticide to cut down the aphid mass and I am afraid that there is nothing much you can do to cure the problem.  I do however feel that it is worth mentioning that your Lime Tree will grow to hundred feet plus and if it is close to the house it may be worthwhile seriously considering pruning the tree.

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Edward Gibson asks...

I have an orange tree and a lemon tree in pots. I move them in to the green house in the winter how do I get them to produce fruit?

Bill replies...

I have listed below some cultural tips Edward which I hope you will find helpful and, will assist in producing fruit on your trees.

Citrus fruits are outdoor container plants but, they need to be placed indoors over the winter months.

When repotting I would use a soil base compost such as John Innes No 2 or No 3.  The compost should have a pH of approximately 6.5/7.

As mentioned above Citrus fruits should be placed outside during the late spring and summer months but they do not like too bright and warm conditions and, also during the summer months spraying the leaves over will increase humidity and pollination.  You will also need to regularly feed through the spring and summer months with a specialist Citrus Fertiliser which can be obtained from good garden centres.

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Fred Hill asks...

My mock orange has not flowered this year when should it be cut back and how low should it be cut?

Bill replies...

Your Mock Orange (Philadelphus) should be pruned back after flowering - which is early summertime - as the flowers are produced on the previous season's growth.  You can also cut back at this time of year any old branches. You will find that the Mock Orange will survive in poor soil and tends to produce masses of flowers under these conditions.

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Alison Brookes asks...

I have an orange tree in my conservatory which seems to be dying. Last summer it grew many oranges which I had to remove due to leaf drop, the leaves appear to be brown and crispy. Can you please advise me on what to do? It has also been repotted.

Bill replies...

Citrus fruits including your Orange Tree Alison are very temperamental and why the leaves are droping could be for a number of reasons.  It could quite easily be temperature shock, lack of water and dry humidity.  It is however worth pointing out that all Citrus fruits will drop their leaves, they do enter dormant periods - where leaf drop will occur - but this does not mean that your plant is dying - it will start to shoot again and listed below some cultivation tips which I hope you will find useful:

Citrus plants are far better growing outdoors during the summer months - requiring a temperature of 7 to 12 degrees C.  Do not keep them in a greenhouse over the summer months as the temperature will be far too hot - they need to be situated in dapple or light shade.  Citrus fruits do not like having their roots disturbed but, if your plant is really potbound you can repot early springtime into a slightly larger pot.  Water with tepid water if possible and feed with a general fertiliser from March to October.  There are specialist fertilisers available for Citrus Trees.  Leaf curling is a sign of low humidity.  During the winter months your plant will need to be kept in a conservatory at a temperature of approximately 10 degrees.

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Katie Halls asks...

On the citrus trees in the garden, there seems to be a combination of two pests, one white and woolly under the leaves which has attracted ants, so I'm wondering if it is aphids also something that seems to be leaving a ziggy zaggy line on the leaves and they are curling, any suggestions?

Bill replies...

You are correct in saying that we are dealing with two pests Katie.  The white woolly pest could either be woolly aphids which secretes a waxy coating which protects the aphids from predators but, these aphids usually congregate around the stems and young shoots.  The other pest could be the Mealy Aphid - these aphids have a waxy like coating and usually appear on the under side of the leaf. Both of these aphids will secrete a sugary glucose substance which will attract ants.  The ziggy zaggy lines on the leaves of your Citrus plants will have been caused by Leaf Minor and the grubs of these insects burrow into the leaf and feed on the leaf tissue and this is what caused the zig zag affect and if you look closely you will be able to see the tiny grubs and these can be squashed between finger and thumb.  Because we are dealing with a food crop I am always reluctant to recommend an insecticide spray but there are contact safer insecticides available which contain a fatty soapy liquid which can be used on food crops but, you will need to read the instructions carefully.  These will keep the aphids under control but will not kill the Lead Minor Grubs and if may be better for you to just remove the affected leaves.

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Jo Edwards asks...

We have a lemon tree, that's about 5ft tall, its not bearing fruit, but the leaves are very strong in citrus smell, it's doing really well but we keep finding little larva wrapped in a silk like substance that curl the sides of two leaves together. We have never seen any sign of a beetle/moth/insect and are totally baffled to what they are. Hope you can help, thanks.

Bill replies...

The pest you have described Jo is Mealy Bug and it is quite a common pest of citrus trees. The silky fluffy substance that you describe protects the Mealy Bug from predators and both the adults and young extract sap from the plants.  Clusters of these pests are often found on the stems and leaves axles and also on the underside of the leaves.  If you only have one or two clusters the easiest method would be to wash these clusters off with a damp soapy cloth rather than spraying with an insecticide spray.

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Jim Benton asks...

I want to move a three year old orange tree, what is the best time of the year to do this?

Bill replies...

During the winter months Orange Trees Jim are semi-dormant and I would wait until late February/early March before transplanting your tree.  Orange Trees can be easily grown in large pots (10-15 inches) in conservatories and greenhouses and although frost sensitive they will tolerate cool conditions over the winter months.  During the summer months they will appreciate being placed outside in the garden.  They need regular watering and also feeding.

last updated: 07/05/2008 at 15:21
created: 20/10/2006

You are in: Lancashire > Nature > Features > Ask the gardener: Oranges, lemons and limes



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