Outdoor Meyer Lemon Tree - Signs of slight yellowing on the leaves

[Artisan]

I have a young Meyer lemon tree which has been growing outside in a container since the early part of June this year. The small tree is planted in Citrus compost and is fed weekly with a liquid Summer Citrus feed. The tree appears to be healthy with new leaf growth showing but I have just noticed that quite a few of the older leaves are showing small signs of some yellowing. I have read that signs of yellowing on the leaves of citrus tree are possibly caused by the Red Spider Mite but then goes on to say that this only occurs with citrus trees kept undercover in conservatries and greenhouses. As my tree has been outside since June I am at a loss as to what might be happening to tree. If anyone has experienced the same or knows what the problem is I would be grateful to hear from them.

[BUFFS]

As far as I know at this time of year you should be using a different fertiliser to the one used in summer and cooler weather will trigger a reaction in the leaves, they are not going to flourish in the colder weather, they may not **** down completely but will not be more than ticking over until the daylight hours and the temperatures increase, they will look pretty tatty until then..

[nickdub]

Been pretty wet and cool the latter half of the summer - maybe the compost in the pot got a bit too damp ? You can't really do all gardening by a set timetable like watering weekly - the weather conditions etc are too changeable.

[Snadger]

I have one outdoors and one indoors. All the leaves look yellow (but healthy)? on the outdoor one but the indoor one has lemons on it and is flowering again. The summerhouse has a lovely lemony smell to it!The indoor one has nice dark green leaves.
I think I will bring the outdoor one indoors soon and hopefully it will perk up.

[Artisan]

Thank you. Once again a great Help.