Hardy Herbaceous Perennials – Planting

Herbaceous plants can be planted at any period during the dormant season. This lasts from mid-autumn until early spring, although it is possible now to plant con­tainer grown perennials all the year round. Unfortunately this restricts the diversity of plant material at your disposal as only plants that do well in containers are sold that way. It is also likely to be hot and dry during the summer and container grown plants need constant nursing in order that they become established, watering being of the utmost importance. If you have to plant during the summer months from containers, then ensure that the potball of each plant is thor­oughly soaked before planting. If the plant has been in its container for a long period of time the rootstock may have become very woody and may well need teasing out before planting. Roots that are growing in a con­gested corkscrew fashion and which become hard and woody rarely break out of their rootball and ramify the surrounding soil without assistance.

Traditional autumn or spring planting presents none of these difficulties. All that is required is that each plant is firmly planted in a hole which is of sufficient dimensions to ensure that the fibrous roots are not cramped or congested. Some herbaceous plants become totally dormant during the winter and do not even leave a reminder of their presence in the form of a woody with­ered flower stalk. These all require marking with a small cane after planting. The soil all looks the same once the plants are in as it is very difficult to remember what was planted where. Liberal applications of slug pellets amongst the most vulnerable plants like lupins and delphiniums is a necessary pre­caution, for plants like this produce succu­lent shoots during early spring which are the delight of these slimy predators. A ring of weathered soot or ash around each group of vulnerable plants is a good slug deterrent.

Freshly acquired plants are ready pre­pared for planting, but if you are reorganiz­ing your own border you will obviously wish to retain some of each of your existing stock. Most will be capable of division, the easiest and most reliable means of increas­ing them and ensuring that they remain true to type. Some border plants produce single vigorous tap roots and are indivisible. These are the ones that are usually reproduced from seed or short stem cuttings. Plants with an abundant growth of fibrous root are the ones most suited to division. Established clumps of perennials should be carefully lifted with a garden fork and as much of the surplus soil as possible shaken off the roots.