Yes, it’s February as I write this. These wonderful plums, also known as Mirabelles, are ready to pick in around August, but there is good reason for mentioning them now – they are in flower. The pretty blossoms are distinctive, there’s nothing else to confuse them with at this moment and you can spot them as you drive past at 60. If you track them down now, you can head back later in the year for their fantastic fruit. Get your skates on though as the Blackthorn will be out before too long. Yes, it’s still worth knowing where Blackthorns are for your Sloes, but Cherry Plums are less common. The focus of this post is telling them apart. One blog I found gives one possible way:
Cherry Plums

Flowering period: Can flower as early as late January, but can carry on into March and April
Twigs: The young twigs are hairless and distinctively green. Bark dark grey. No spines.
Flowers / leaves: The leaves develop at the same time as the flowers.
Habitat: Scattered, but locally frequent and easily overlooked when it grows in hedges with Blackthorn but given away by the early flowering. Can make a small tree (up to 8 metres). They are non-native, and sometimes used for landscaping or highways planting.
Appearance: Distinctly wispy with slender branches and twigs.
For more information on identifying Cherry Plums see this Woodland Trust page.
Blackthorn

Flowering period: March – April
Twigs: The dark brown / black bark is smooth, and twigs form straight side shoots, which develop into thorns / spines.
Flowers / leaves: Flowers appear before the leaves start to show.
Habitat: Grows naturally in scrub and woodlands, but commonly used in hedges. Can grow to 6 or 7 metres tall.
Appearance: Usually an impenetrable mass of very spiny straight-branched bushes.
For more information on identifying Blackthorn see this Woodland Trust page.