The greengage plum is the best-known English plum tree. You may find several varieties of greengage, including Bryantson, Golden Transparent and Laxton's Supreme and Old English Greengage. Greengage plums ripen in July and have yellow-green skin and yellow flesh. They have a sweet honey flavour with low acidity. The fruits are small and oval-shaped and are excellent in jams and pies or eaten straight.
Check the limbs and branches of your English plum tree for signs of dead, diseased or damaged branches. Dead branches will feel hollow to the touch. Diseased branches will have exterior damaged such as splotches or signs of discolouring, and damaged branches will show a wound.
Prune away damaged or dead branches at their intersection with the main branch. Place all cuttings in a garbage bag and remove from the site. Carefully disinfect your pruning shears when you've finished removing bad wood to avoid contaminating healthy parts of the tree.
Cut away low-growing branches that impede movement under the tree. Also remove branches that are growing downward. Snip off suckers and water sprouts.
Thin the canopy to allow sunlight to reach the inner branches. You'll want to cut off branches that are rubbing up against other branches and branches that grow straight up toward the skin. Trim back the tips of new branches to encourage additional growth. Your plum tree will only bear fruit on wood over one year old, so don't worry about losing out on fruit yield.
Remove any shoots that threaten the central leader. Plum trees work best with one main upward-growing shoot, so if you notice competitors emerging beside the main shoot, trim these off.
Since European-style plums are smaller than Japanese plums, an English plum tree will require little fruit thinning.
Prune plum trees in mid- to late summer after you have picked the year's harvest. Pruning during the winter leaves them vulnerable to silver leaf disease.