Apple tree does not bloom

In the case of the Cox Orange Renette and the Holstein Cox, you have chosen two apple varieties that taste delicious but pose several challenges to pruning in domestic gardens which need to be overcome if they are to yield fruit on a regular basis – especially in the case of the Holstein Cox, which is by no means a vigorous variety. The Gravenstein is also known to alternate between heavy and light-cropping years (it is known as an alternate-bearing variety). In terms of the conditions for fertilisation, however, your three should do okay. The Holstein Cox is a poor pollinator, but the Cox Orange Renette, in contrast, is what we call a "universal pollinator". In heavy-cropping years the Gravenstein also performs reasonably well as a pollinator.

In terms of cultivating high-quality individual fruits, it is correct to thin the fruit sets out well. This should not be done, however, until after the so-called June fruit drop when the apple tree will trim itself in the first instance. Only then will it be possible to identify with any degree of certainty whether any further thinning out is needed. If it is, then clusters containing more than two fruits should be reduced to just one or two per cluster about every 20 cm along the branch. As a rule of thumb, it takes around 35 leaves to nourish one apple. That said, this is by no means an exact science!

If the remaining apples were smaller than usual (the two Coxes are varieties that produce small fruits anyway), then it may be that the hangings were still too large, nourishment may have been poor, or even the weather may not have been conducive to a good crop. You can improve the nourishment situation by providing the right sort of fertilisation for the trees: incorporate around one to two litres of compost per square metre into the drip area of the crown. As the apples had gone rotten, it's worth checking whether this happened as a result of a fungal infestation of the fruit caused by, for example, damage from feeding insects such as codling moths, or cracking damage due to scurf. Without seeing it my guess would be that we're looking at a yeast infection called Monilia which occurs quite frequently during the fruit's ripening phase. If I'm right, then you need to monitor the trees for any infestation with the codling moth and/or apple scurf. You can tackle both of them, but not Monilia itself directly.

The low number of flowers produced this year may well be down to the alternate-bearing nature of the variety that I referred to earlier. The abundance of water shoots would suggest to me that when you thinned them out last year you somehow broke off some of the short shoots on which the clusters of flowers were hanging. The plant will then respond by forming water shoots. Improper pruning of the apple tree can also be a cause of the problem. It's best to break these water shoots off as they are formed. You can do that at the beginning of July. The important thing to remember is that you should not cut them off, but actually break them off, together with the base of the shoot.