How to grow Hypericum

Rust on hypericum

Hypericum at a Glance

  1. Easy to grow, vigorous to  very vigorous
  2. Tolerates semi shade
  3. Does not require pruning
  4. Can be prone to rust- see image left
  5. Can be decidudous, semi-evergreen and evergreen
  6. Height varies from tall shrubs to dwarf  and ground cover varieties

Hypericum is  commonly known as St John's wort. Most varieties are deciduous or semi evergreen and summer flowering with lovely bright yellow flowers and followed in autumn by attractive berries. There are many varieties but those commonly sold and  grown in gardens are H.x hidcoteense 'Hidcote' and H. calycinum 'Brigadoon'.

Hypericum is easy to grow being tolerant of most growing conditions and it tends to be vigorous with a tendency to self seed. It is very tolerant,  Hypericum will put up with drought and shade, (although flowers best in sun) but dislikes waterlogged, damp soils. Hypericum has a long flowering season and carries a profusion of blooms as the image top right illustrates.

There is no need to prune other than to remove any dead wood in the spring.    

There are also dwarf varieties suitable for front of the border or rock gardens such as Pallens

Another plus point of Hypericum is that it is ideal to have as a cut flowers both the blooms and later the berries are attractive and frequently used in flower arrangements. 

Between 2015-2018 the RHS undertook a trial of Hypericum assessing varieties for shrub shape, flower quality and lengh of flowering, autumn fruits and disease resistance. 

Hypericum  Calycinum retained its AGM, and it is a low growing, spreading type, only 60cms high and is good for grown cover. It will spread quickly, quite vigorously, and is bordering invasive and each plant will spread up to 1.5. 

Hypericum Hidcote image left is a very popular variety which also retained its RHS garden merit award and grows up to around 1.2m so suitable for the back of the border and even for hedging.

Also H. x moserianum is a dwarf variety growing up to .5m with reddish stems and very hardy H5.

Hypericum kouytchense is another short variety up to .5m with large flowers and good autumn berries. Most of these varieties are readily available.

 For an explanation about frost hardy

How to prune Hypericum

It is not essential to prune Hypericum but if pruning is needed spring is the time to take the shears to it.

A light prune in early spring if you want to restrict size or tidy up. Some Hypericum are prone to rust and pruning in the spring is one way to remove rust tainted branches. Hypericum also self seed quite a lot which is a plus or minus depending on what you want in your garden.

To reduce the problems with rust, the shrub can be cut down at the end of summer and all the rusty leaves removed for a fresh start in the spring. It will still flower and produce berries as Hypericum flower on the current years wood. In particular, H. calycinum which is vigorous and can be prone to rust so  will enjoy being cut back annually to the ground in around February /March time. Generally, Hypericum flowers from July to October.

 

Fully ***hardy and easy to grow. Most Hypericum need little or no attention and grow in almost any conditions.

Last updated 21.01.2020