What’s a herbaceous perennial and why should you grow them?
Herbaceous means ‘relating to plants’, and perennial means ‘lasting forever.’ So a herbaceous perennial is a plant that will last – maybe not forever – but for many years. Basically, the leaves and stems of herbaceous perennials die down over winter but come up again in the spring. Some perennials might keep their leaves over winter – especially in milder areas, such as here on the South Coast.
There are a huge range of herbaceous perennials, and they include our most beautiful and spectacular garden plants. Just think of those traditional borders in National Trust gardens and you get the idea! Herbaceous perennials require more maintenance than shrubs, but less than annuals or bedding plants.
How to garden with herbaceous perennials:
Unlike shrubs, herbaceous perennials need to grow new stems and leaves each season. This requires a lot of energy. As plants get their energy from sunlight, most herbaceous perennials therefore need a sunny or part sunny position in the garden. However, there are still plenty of herbaceous perennials which will grow well in shade. Often these are smaller plants which flower earlier in the season. The reason for this is that they have evolved to grow under deciduous trees, and so finish flowering (which requires the most energy) before the trees come into leaf and cast them into shade. Other herbaceous perennials which do well in shade are those with big leaves, which are more efficient at capturing sunlight.
If you’ve got a sunny spot for your herbaceous perennials then the sky’s the limit!
During the year, herbaceous perennials need feeding and some will need staking and dead-heading. Some need protection from slugs or snails – particularly early in the year when new, tender (and delicious) growth is emerging. Every few years herbaceous perennials will need to be dug up and divided, as they tend to get congested and less vigorous.
Some herbaceous perennials are more tricky to look after than others, so if you want to reduce your maintenance, it’s worth doing your research and choosing ‘easier’ plants.
In autumn, herbaceous perennials will die back, as they prepare to overwinter. The roots remain living, but dormant, in the soil. It’s a matter of hot and acrimonious debate whether to cut back dead foliage in autumn or spring. Traditionally, gardeners did an autumn tidy up, removing all dead growth. However, more recently, others have advocated leaving growth until spring, providing shelter for wildlife.
I think it’s a personal choice! If the plant has been infected with a virus or fungus, it’s better to remove everything in autumn. Some plants have attractive structures which you can leave over winter. Sometimes you just have to do things when you’ve got the time (and the weather is nice!). A compromise would be to cut back some in autumn, and others in spring – perhaps leaving those which provide the best ground cover for wildlife such as newts or toads.
I’ll be uploading some more information about recommended herbaceous perennials for different soil types and situations soon.
Have a look at Pages 98 – 110 of our textbook – RHS: How to Garden.
More links coming soon!