Home Page

Nursery:
Online Catalogue
Printable Catalogue  
Online Order Form 
Delivery charges etc. 

One of the questions we get asked in November is "which plants should I cut down and which should I leave?".  There's not a standard answer to this but perhaps a few pointers will help:

Firstly does the foliage still look good? If it does then leave it (for now). Lots of perennials can add interest to the winter garden with architectural outlines, such as grasses, dramatic effects in the frost like erygiums, phlomis etc and with attractive seed heads like Centaurea macrocephala or Cynara carduncularis. It makes sense to leave these through the winter. However be aware that some need cutting back before new growth starts. For example if grasses are left uncut after new growth starts then it is a really difficult task to cut out the old growth. 

The latter point also applies to siberica and ensata iris. The leaves die off now and add nothing to the winter scene so it is worth cutting back now to avoid a more difficult task in early spring.

If the leaves or stems harbour pests or diseases it is worth cutting back now. For example Phlox eelworm migrates into the soil in winter so be cutting the stems back to the ground and disposing of them you reduce the chance of problems next year. The same is true of Helenium with the added problem that the falling soggy dead leaves settle in the crown and cause grey mould (botrytis) in the crown. Hemerocallis and Agapanthus leaves can harbour leaf streak or can go mushy in frost causing crown rots. 

Cutting stems back to the ground rather than leaving a stump stops earwigs using the hollow stems as a winter refuge.

Another reason to remove dead stems is excessive self seeding. For example Digitalis ferruginea, the Rusty Foxglove, sheds most of its seed in winter as does Francoa sonchifolia. So removing the flower stems (and remembering to hold upright until safely in a bag) reduces the amount of seed in the soil. Of course the opposite is true, leaving on seed heads of plants that we want to self seed is essential: Helebores are prime examples - difficult to germinate in seed trays they do well as self seeds.

Some plants benefit from leaving dead foliage on. This is particularly true for marginally hardy plants like some Salvias and Lobelia tupa: leaving the top growth on protects the crown from frost to some extent. 

Evergreen perennials should normally be left although most will benefit from a good cut back in February, e.g. Francoa and Heuchera. (The National Collection Holder tells us to prune Heuchera in September - Martin Oct 09)

With the Red Hot Pokers (Kniphofia) it is not clear cut. Some are deciduous in hard weather but providing the leaves aren't a soggy mess then they can protect the crowns. Other ones, like rooperi, keep their leaves through the winter but these leaves will die in April once fresh growth start coming through. Provided it isn't too cold I normally cut these back in early March.  

We get a lot of questions about winter treatment of Salvias. The old world types are tough and can either be left through winter or cut back hard. The new world types should have all their top growth left on and be tidied up in spring.