So let the skull mashing explanation begin. If you buy a Triploid tree, that basically means it will not pollinate other apple trees nearby but it requires pollen for it to bear fruit. So if you buy another apple tree to pollinate your TRIPLOID variety then you need to be aware that this second apple tree will not be pollinated by the TRIPLOID and therefore will not bear fruit.
The easy fix for this is to ensure that the second tree you purchase to pollinate your triploid is self-fertile and is within the suitable flowering group. This is because the blossoms of both trees need to be open at the same time to allow cross pollination by insects, wind etc. So if your Triploid tree is in flowering group C3, you need to buy a self-fertile tree in groups C2,C3 or C4. The apple trees also need to be different variety e.g a Discovery apple tree will not pollinate another Discovery apple tree.
The downside to using a self-fertile tree to pollinate a triploid variety is that there are considerably less self-fertile apple trees than there are non self-fertile. Examples of self-fertile apple trees are Cox Orange Pippin (C3), Ellisons Orange (C4), Greensleeves (C3), James Grieve (C3), Keswick Codlin (C1), Red Devil (C3), Red Falstaff (C3), Red Windsor (C2), and Scrumptious (C3).
So if you are in the position of having a triploid tree e.g. Bramley 20 (C3), Bramley Original (C3), Bramley Seedling (C3), Blenheim Orange (C3), Catshead (C3), Crispin (C3), Jupiter (C3), Jumbo (C3), Red Prince (C3), Ribston Pippin (C2), Scotch Budget (C3), and Tom Putt (C3) and do not want to use one of the self-fertile varieties to pollinate it, then you will need at least one other apple from a suitable flowering group. However, this second tree will not pollinate from the triploid so you will need a third tree to pollinate the second.
You do not have to do this but it seems a shame to have an apple tree that does not bear fruit.
There is an exception and it is a risk. Pollen can be carried for at least 4 miles by a bee, possibly further by the wind. So if you live in a built up area where there is likely to be other apple trees it is possible to likely that your trees would be cross pollinated. Personally speaking, as apples only come round once a year, I am impatient and tight with money, I would want to make sure my trees bore a heavy crop every year and so would buy the one self-fertile or the two non self-fertile apple trees.
So in a complicated summary that is meant to be easy reading, if you buy a Triploid variety of apple tree, to ensure pollination and a harvest of apples you will need another self-fertile apple tree from a suitable flowering group or two other non self-fertile apple trees, one to pollinate the triploid and another to pollinate the pollinator! If you have understood this as I have meant it to be read then you should understand that the second tree will pollinate the third so all three trees will bear fruit.
So possible frequently asked questions could include:
Q: Can you say all that again but slower?
A: Yes we know what you mean, try moving your lips as you read and run your finger under the words.
Q: What do I need to do if I buy a Triploid variety and get fruit?
A: Read this again or call us on 0800 043 1057
Q: Will a C2 pollinate a C4 or C5?
A: No, a C2 will only pollinate a C1, C2 or C3
Q: If my Triploid tree is a C3, what do I need to buy?
A: I thought I just explained all that!! However, you need a self-fertile tree from groups C2,C3 or C4 or as a minimum a non self-fertile tree from these same groups. If you want the second tree to bear fruit also then you need a third tree from a suitable flowering group which can be either self-fertile or non self-fertile. I sense you would probably prefer to call at this point...0800 043 1057.