Posted: 06/08/2013 at 19:02
Hi shelley, they should already have fruit visible on them and would have blossomed in spring. If you can't see any fruit, it is possible that a late frost damaged the blossom. In general, the older a tree the better it will fruit, but very old trees may be diseased and not fruit well. If that's the case the best thing is to remove them rather than trying to renovate them. You can't really cut large mature fruit trees back hard without risking killing them. However, now is the time to prune plums and you should remove any dead, damaged or diseased branches. Exactly how big are they?