Hi...Congrats on your seedling, now tree.
How long do the temps remain under 40F degrees in your area..Sorry, can't convert to C.
Some ppl leave their citrus outside through frosts, but set in a sheltered spot like a garage..Also, I'm told outdoor Christmas lights work, placing atop soil will keep warmer..Is it possible setting lights on your citrus?
Keep plant out of icy winds. Hopefully, your veranda and being set up against the house will resolve this problem.
I don't agree giving citrus a winter climate will promote flowers/fruit..on the contrary. I keep my citrus cooler in winter, however no colder than 40F.
It's not impossible for a seedling to flower/fruit, just takes longer. I've read betweem 7-14 yrs. I'm sure your lemon isn't grafted, right? Is it bush-shaped? Non-grafted trees take longer to fruit. Is your lemon bush-shaped?
Citrus are big eaters..If you can't get hold of citrus food, how about Azalea fertilizer? If not Azalea, how about something high in Nitrogen? I'd apply some type of food, until you can locate the proper fertilizer.
Sorry, I don't know of any home-made recepies for citrus fertilizer. What are the numbers on your houseplant food.. How about the tomato food?
Have you checked Ebay for fertilizer? They usually have citrus fertilizer available.
Otherwise, go to www.gardenwatchdog.com ...Click on nurseries in England, this way you won't have to pay high-prices for shipping sent from the US. GWD lists nurseries in England..Perhaps you can find garden supplies through this site..Good luck, and keep us posted..Toni

Palm fertilizer is often suggested as a substitute for citrus. Palms also have a special need for magnesium, which is always in palm speciality fertilizers. You can use magnesium sulfate, however (epsom salts). To supply the minor elements required by container grown citrus, you can use fish emulsion occasionally or other 'organic' products. They tend to have the minor elements that general fertilizers don't.

I don't use a special citrus fertilizer. I find the epsom salts in the pharmacy or health care section of my grocery. Fish emulsion is my organic fertilizer of choice. I use the same general purpose soluble fertilizer that I use for all of my other container plants for the N P K.

thanks toni and rhizo.
temperatures vary a bit over winter so, (with my handy F to C converter) i can tell you it stays around 40. we'll think its really cold if it drops to 30, but equally it can be up to 46 or more. also under the veranda it is out of the wind, and frost doesn't reach that far. unfortunately i wouldn't be able to put lights over the soil (having perused this forum i have heard people talking about that). sometimes i've seen people protect tropical plants by covering them in fleece or some other protective material. i am considering doing this on the days the temperature really drops.
and no, my lemon tree definitely isn't grafted. i'm only 20 years old, which is why i can't give you an exact date of how old it is, all i can remember is that when i was really quite young i planted a lemon seed. to my surprise it came up, and it's been my project ever since. it's not a bush shape, more of a standard shape, though a bit straggly.
the houseplant food contains nitrogen 10%, phosphorus pentoxide 4.4% and potassium oxide 1.7 %. the tomato plant food has unfortunately has it's label ripped off so i can't tell you!
thank you for the suggestion of epsom salts, i will have a look for those next time i go shopping, and try them out.
thank you for both taking the time to give such helpful replies.

Hi Reda..I would think your citrus is one of your favorites since you started from seed at such a young age.
How in the world did you get it to grow as a standard? LOL
My citrus fertilizer is 12-6-8 plus minerals.
I forgot about Epson Salts..Rhizo thanks..ES's can be bought at any pharmacy and most grocery stores..I think the container has a dossage section when used for house plants..If you have palm food that would help, too..Do you?
How about doing a search for tomato food? Type in the brand name company and see if they sell the fertilzer you have. But check box thoroughly..sometimes they mention these numbers in different parts of box..outter and bottle/box.
Is your tree thorny? Toni

haha yes my lemon tree is definitely my favourite plant, because it has been with me all through growing up! at the moment it is rivalled by my aubergine plant, but that is due to the novelty of it, and the fact that our summer has been so wet and cold so far i am worried it won't do anything!
and i'm really not sure how i got it to grow standard-like, it just seemed to do it on it's own! lucky really.
i don't have any palm food. would you recommend feeding with the house plant food as it has 10% nitrogen, whilst i am looking for something better? i can't remember the brand of the tomato food, but do they normally contain such things as citrus trees like, or would it be useless to give it any?
my tree is a little thorny, the spikes are about an inch long. thorny enough to give my hands a couple of scratches when i am cleaning it of scale insects a little carelessly.
i am hoping that it is getting of the age where flowers would be a possibility. even if i couldn't get the fruit to set i would be overjoyed with just flowers.

Ah, scale..gotta rid those, Reda..Otherwise they'll take over your plant..
I only use organic or home-made insecticides..Did you ever hear of Fish Emulsion? It's actually an organic fertlizer, but works great as a foliar spray to rid scale..try it..1 capful per 16oz mister of water..spray thoroghly. Those bugs will be gone before you know it. You may need 2 applications but don't worry since it's non-chemcial and won't burn leaves/roots.
I never used fertilziers when growing tomatoes..so don't know its numbers. I could do a check and see if they have info online..I'd imagine most tomato fertilizers are about the same.
I'd use regular plant food until you can find citrus..How about azalea fertilizer? Do you have any lying around? lol..like most ppl would..
BTW, is your citrus tree outside? May have asked before.
I would think after you get rid of those bugs, sufficent fertilizer, and good light, you'll probably see flowers..I hope..Toni

hi toni,
i would love it if you could find out about tomato food for me, as to be honest i don't really understand the numbers on fertilizers, or what i should be looking for for citrus trees. and no, unfortunately i don't have any azalea fertilizer. thanks for the info on fish emulsion (i think rhizo mentioned it too). i am really interested in organic foods/pest control, but i'm actually vegetarian! haha... so probably don't have anything in the house which would mean i could make something similar at home, and actually, probably wouldn't be too keen on using it anyway... mostly i just use cotton wool balls and clean water to wipe away the scale insects a couple of times a year. there aren't too many.
and yes, my lemon tree is outside, under the veranda, which would normally mean it gets some good sunshine and heat but the weather over here in england is just ridiculously bad at the moment. it's raining every day and is pretty cold! the wettest summer on record or something - so we aren't seeing much sun!
thank you for your continuing advice. i am getting a little addicted to browsing these forums, so i will tell you if i EVER get any flowers even if that is in 5 years time! haha...

Howdy Reda,
Do you ever order on Ebay? I was checking available fertilizers..tomato for one..They sell organic tomato foods..But there's so many to choose from. They're all a bit different, too. For instance Cave's Famous tomato fertilizer is 4-7-3 Nectar Tomato is 2-1-4
Agloflash which is non-organic is 4-6-8..
NPK, (N) Nitrogen, (P) Phosphate, (K) Potash..

I wonder if you'd do better w/a Palm fertilizer. One seller on Ebay, sells a palm food called Sunniland. 8-6-6
Nitrogen is important for citrus growth. For instance, my citrus fertilizer is 12-6-8 Notice there is a higher amount of Nitrogen?
There are a few more palm foods, a couple palm spikes, which are, IMO, a waste of money and of no use to plants.
They also sell citrus food, unfortunatly, most are spikes..Sunniland sells one that sounds excellent..there's also an organic citrus food called, Citrus-Tone by Epsoma.
I would imagine shipping charges would be outrageous...
Why not go to www.gardenwatchdog.com ? On the left side of screen, click UK. They'll list a good number of nurseries. You can narrow a search by typing 'citrus fertilizers', or just 'fertilizer' plus get feedback regarding the nursery.

Do you have Home Depots that-a-way? I stopped there today, and noticed 'Osmocote' had Palm and several other fertilizers. They also had a Palm food that said good for citrus, but I can't recall which brand.. LOL

If you see scale, and want an organic, then Fish Emulsion is for you..do I not sound like an ad? LOL..In fact, today I fertlized and Superthrived citrus, hibiscus, etc..As I approached my Olive tree, I noticed it had scale..darn it!! Tomorrow, I am going out w/my mister filled w/FE and water..It's getting a good spray..Had problems w/this Olive tree before..and of course it was sitting adjacent citrus so they'll get a good spray, too..I swear, that plant must be a scale magnet..

Oh Lord, I've no idea how you'd make home-made citrus food..I'm sure somewhere here on GW somebody has posted recepies for fertilizers...Don't forget not only would you need something to cover NPK but minerals also..Iron, mag, etc..lol Oh I scrolled up and noticed Rhizo mentioned Epsom Salts..if you have it lying around, give a shot to your tree. (and other plants, too)

Have you ever tried rubbing alcohol and cotton balls to rid scale? It'd probably work if a plant has few scale..

Don't feel bad about the rain and cold..this last wk, I'd say it's the worse summer in years..cold, rainy and drab..Cold to me is anything under 70F degrees..Today was nice..sunny and warmer..Hope it stays warm or even warmer..
Once the sun comes out, soil gets a chance to dry out, a dose of proper fertilizer is used, and rid ALL scale, your citrus should do fine.

In the meantime, I'd use your house plant fertilizer, until you decide what to do or order another type. I also hope you get your lemon to bloom/fruit..but remember, it needs sun to set buds/fruit. Good luck, Toni