Training an Apple Espalier

Found this link for you Espalier training trees / RHS Gardening Advice Google search is a wonderful tool.

Yes, i've read a few different descriptions of how to train but am still a bit unclear.

My main leader is tall, well above where i want my 3rd tier to be. Should i prune it back (now - is the timing correct?) by simply making a cut just above a point where I can see two shoots forming?

Don't prune the leader now or you will severely stunt its growth and spoil the potential for a good espalier shape (summer pruning slows growth, winter pruning encourages growth).
It should have been pruned in late winter, before the tree leafed-out.
Wait until next winter before pruning the leader.

When you prune next winter, chances are that the uppermost bud will go straight up, while a few buds beneath will start off your next pair of arms. Some apple varieties are much more enthusiastic to produce side branches than others. (You don't mention which variety you have.)

While you're forming the shape of your espalier, keep it well-fed, especially adequate amounts of nitrogen, which will encourage greater leaf and shoot growth to get up to full size more quickly.

thanks for the advice about waiting until next year to prune the leader.

regarding feed. is a liquid tomato feed ok to use? if so how often shod i feed it?

also, assuming i prune the leader this winter, and the 3rd tier grows next summer, should i again remove the flowers next year, meaning no fruiting until the final shape (3 tiers) is reached?

If the tree is growing well, it doesn't need feeding. Ideally it will need to fend for itself one day, so only feed if it seems to be growing too slowly. Feeding in the late half of the season often doesn't show as strong growth until the following season.

I would suggest that after a year to establish, you can start to allow the lower arms to start fruiting, although fruit quality is often poor for the first few years (drops early, small, flavourless, bitter pit), assuming that the pests (maggots, wasps, birds) don't get those few fruits before you do.

I the tree sends out strong shoots (and to keep the tree within its allocated space), you can prune strong new growth back hard in July, which will convert such shoots to fruiting spurs for the next season.
Apart from the leader, any other upright shoots should be pruned hard in July to leave just an inch or two of new growth.

While you're forming the various tiers, prune the leader in winter, which will cause vigorous regrowth of multiple shoots just below the cut, which will be trained along 45-degree-angled canes during their first year of growth and then lowered to almost horizontal in the winter after their growth.
Don't prune the leader in summer until you have all the tiers of arms in place.
Once all tiers are complete, prune the leader back each summer, to leave only about an inch of new growth. This will stunt the leader and redirect energy to the arms for fruiting.

"regarding feed. is a liquid tomato feed ok to use?"

Just to clarify on a "Nitrogen feed" (I dunno about feeding fruit trees), Tomato feed won't be high Nitrogen feed. Use something like Sulphate of Ammonia.

On the fertilizer packs you should see an "NPK" ratio followed by three numbers 1:2:3 - the first is the N, then second the P and the third the K. You are looking for something that is mostly "N".

10:10:10 is the same as 20:20:20 - you just need half as much of the 20:20:20

So what you are looking for is something that is 10:0:0; again, if you find 20:0:0 its the same (just Nitrogen) but you only need half as much), or find something where the first number is much higher than the other two.

Yes, for the first few years, I'd suggest at least 1:1:1 - N:P:K ratio (something like Growmore is 7:7:7 and works quite well as an all-purpose).
In later years you don't want much nitrogen because it will cause vigorous growth, lack of fruit and poor quality fruit. But you'll need good amounts of P and K for best fruit quality.

Is there a school of thought to use high Nitrogen in the early years to get plenty of growth on the laterals to get them established?

And then switch to fertilizers more beneficial for Fruiting once established?

I'm thinking: What do you do if, having pruned correctly in the Autumn / Winter, the laterals for the new tier being trained don't grow as "wide" as hoped (and which I am thinking a Nitrogen fertilizer would help achieve)

thanks for this. i've researched quite a bit and this is the the clearest, most concise advice i've found!