Pruning Sweetshade, Hawaiian Wedding Tree (Hymenosporum flavum)

Question from Katie:
Can you please tell me the best time to prune my large sweetshade trees? (I live in coastal Long Beach.) Obviously I want to prune them to be able to enjoy a full bloom but avoid the fall and winter winds. Thanks for any advice you can give. I’m a big fan of your books!

Answer from Pat:
Sweetshade or Hawaiian Wedding Tree (Hymenosporum flavum), an evergreen tropical flowering tree native to Australia and New Guinea, prized for its abundant yellow, spring and early-summer blooms that can bowl you over with their fragrance. Hymenosporum has only two bad habits and they can be corrected:

They send out branches in three’s that are unevenly spaced up the trunk and then they grow most foliage onto branch tips. These problems can be overcome with frequent pinching or light cutting back of tips while the tree is young but you can continue this practice into maturity if necessary. If a branch gets overly long, just climb a 3-legged ladder, if you have one, and shorten it, (but don’t break your neck!)

Pruning of evergreen tropical trees is best done during the warm months of the year so that you don’t encourage growth in winter when you want the tree to harden off and withstand any cold snaps with equanimity. With most flowering evergreen tropicals you won’t go wrong by following the rule “Prune after bloom”, but pinching back to encourage bushiness can be done during any warm month from March through September, even when the tree is in bloom.

You are lucky to have mature specimens of hymenosporum. We used to see only small ones growing in Southern California, but in recent years we are seeing many older ones, some of which were planted in groves as apparently yours were. This can be good since the trees tend to support one another, but if they eventually become 60 feet tall, as in Australia, I think some of these groves will need thinning by taking out a trunk here or there. So far I haven’t seen any cases of this being necessary. Instead these older groves look like large screens and true ornaments to the Southern California landscape. I would deplore the loss of any of them.

Once Hymenosporum are full grown they are usually fairly trouble free but if they weren’t trained well in youth weak and breaking branches could be a problem. With your trees, look them over for weak branches and take those out or if that would leave unsightly gaps, leave them growing but cut them back to encourage branching. In most cases cutting back by several feet is sufficient to solve the problem. Don’t allow your tree pruners to “lace out” this tree. That would be exactly the opposite of what you want. All the pruning you should do is to force more growth to the center by cutting off some of the outside. Never clean out the inside of the tree, which would only make matters worse. In any case, don’t ever allow your tree pruners to remove more than 20% of the growth and foliage of a mature hymenosporum tree at one time.

I love this tree and am glad you have large ones. I’m also pleased you enjoy my books.