1. Herbaceous Perennials

2. What is a perennial? A (herbaceous) Perennial is an herbaceous plant with a life of more than 2 years. A (herbaceous) Perennial is an herbaceous plant with a life of more than 2 years. They are sometimes sub-divided into hardy perennials that can safely be left in the ground over winter, and tender perennials that need some protection. They are sometimes sub-divided into hardy perennials that can safely be left in the ground over winter, and tender perennials that need some protection. The above ground growth usually dies back in winter but a few are evergreen which means they retain some leaves over winter. The above ground growth usually dies back in winter but a few are evergreen which means they retain some leaves over winter.

3. Uses of perennials Herbaceous borders Herbaceous borders Part of mixed borders Part of mixed borders Temporary infill between shrubs Temporary infill between shrubs Some suitable for ground cover Some suitable for ground cover Containers (particularly tender perennials) Containers (particularly tender perennials) Cut flowers Cut flowers

4. Perennial Borders & Mixed Borders They are used in the garden to provide a “splash of colour” from late spring to late autumn. They are used in the garden to provide a “splash of colour” from late spring to late autumn. Traditionally they have been used in borders and beds containing only herbaceous plants and bulbs. Traditionally they have been used in borders and beds containing only herbaceous plants and bulbs. The disadvantage of any bed or border consisting of only perennials is that for a large part of the year it will be bare and uninteresting. The disadvantage of any bed or border consisting of only perennials is that for a large part of the year it will be bare and uninteresting. Because of this and the general reduction in the size of gardens, perennials today are also used in mixed borders with other plants, mainly trees and shrubs. Because of this and the general reduction in the size of gardens, perennials today are also used in mixed borders with other plants, mainly trees and shrubs.

5. Main requirements: Soils – By carefully choosing the right plants, herbaceous borders can be established on most soils. The overriding requirement is good drainage particularly in the winter. Soils – By carefully choosing the right plants, herbaceous borders can be established on most soils. The overriding requirement is good drainage particularly in the winter. Weeds – It is very important that all perennial weeds are removed before herbaceous plants are planted, as control later is very difficult. Weeds – It is very important that all perennial weeds are removed before herbaceous plants are planted, as control later is very difficult. It is normal practice to lift and replant a portion of a border every 3 – 4 years in order to control perennial weeds. It is normal practice to lift and replant a portion of a border every 3 – 4 years in order to control perennial weeds.

6. Main requirements: Choice of plants – there are now a very wide choice of plants, colours, shapes and sizes of plants available so careful choice is vital to get the desired effect. Choice of plants – there are now a very wide choice of plants, colours, shapes and sizes of plants available so careful choice is vital to get the desired effect. It is always better to plant in groups rather than single plants, this helps to give a more natural look to the border. It is always better to plant in groups rather than single plants, this helps to give a more natural look to the border. Planning – there are two main types of borders, the conventional border that was usually planted with a hedge or wall as a backdrop and the newer island beds that can be viewed from all sides. Planning – there are two main types of borders, the conventional border that was usually planted with a hedge or wall as a backdrop and the newer island beds that can be viewed from all sides.

7. Conventional single sided border The effective width of these borders is approximately 4m allowing for the rear plants to reach up to 1.8m high. The effective width of these borders is approximately 4m allowing for the rear plants to reach up to 1.8m high. If this cannot be accommodated then reduce the width and also reduce the height of the border (3 layers of plants instead of 4). If this cannot be accommodated then reduce the width and also reduce the height of the border (3 layers of plants instead of 4).

8. Island Beds These have a number of benefits over the traditional border in that they:- These have a number of benefits over the traditional border in that they:- Plants can be seen from all sides Plants can be seen from all sides All plants get the same amount of light All plants get the same amount of light Air circulation is better Air circulation is better There is a lack of competition compared to a border against a hedge There is a lack of competition compared to a border against a hedge Maintenance is easier as the plants are accessed from all sides Maintenance is easier as the plants are accessed from all sides These beds should have their tallest plants near the centre. These beds should have their tallest plants near the centre.

9. Season for Effect The main flowering season for perennials for effect extends from April to November, so it is possible to make a section of plants to cover this whole period or just to concentrate on a shorter period of time if preferred. The main flowering season for perennials for effect extends from April to November, so it is possible to make a section of plants to cover this whole period or just to concentrate on a shorter period of time if preferred.

10. Maintenance of Perennial Borders Maintenance of Perennial Borders Watering: Perennials in general are shallow rooting and should be watered in periods of little or no rain. Watering: Perennials in general are shallow rooting and should be watered in periods of little or no rain. Feeding: Apply a balanced fertiliser feed, such as Growmore in early spring at the rate of 25g/sqm. Feeding: Apply a balanced fertiliser feed, such as Growmore in early spring at the rate of 25g/sqm. Weed control: Beds should be kept free of weeds which can get very entangled with the plants and be difficult to eradicate. Weed control: Beds should be kept free of weeds which can get very entangled with the plants and be difficult to eradicate. Applying weedkillers is very difficult because of the danger to the perennials, hand weeding, hoeing or mulching are the best options. Persistent weeds can be painted with materials like Glyphosate. Applying weedkillers is very difficult because of the danger to the perennials, hand weeding, hoeing or mulching are the best options. Persistent weeds can be painted with materials like Glyphosate.

11. Maintenance of Perennial Borders Staking: Some of the taller plants will require some form of support. There are a number of different types of stakes that can be used including Bamboo canes, twiggy pea sticks, or specialised linked metal pins Staking: Some of the taller plants will require some form of support. There are a number of different types of stakes that can be used including Bamboo canes, twiggy pea sticks, or specialised linked metal pins Dead heading: Regular dead heading will keep the plants flowering longer. Dead heading: Regular dead heading will keep the plants flowering longer.

12. Maintenance of Perennial Borders On some plants like Delphiniums and Lupins cutting right back to the base after flowering may induce a second flush of flowers. On some plants like Delphiniums and Lupins cutting right back to the base after flowering may induce a second flush of flowers. There is a present trend not to cut the flower head off in late autumn as previously done, but to leave them until late winter or early spring. In this way the dead stakes provide some winter interest and also seeds provide food for wildlife. There is a present trend not to cut the flower head off in late autumn as previously done, but to leave them until late winter or early spring. In this way the dead stakes provide some winter interest and also seeds provide food for wildlife.

13. Maintenance of Perennial Borders Dividing: Many perennials lose their vigour as they get older and need to be divided and replanted. This is necessary every 3 – 4 years and is best carried out in the autumn or early winter. Dividing: Many perennials lose their vigour as they get older and need to be divided and replanted. This is necessary every 3 – 4 years and is best carried out in the autumn or early winter. Dig up the old plant and separate it with a knife, spade or two forks back to back. Replant the best healthy pieces with a good root structure from the outside of the parent plant. Dig up the old plant and separate it with a knife, spade or two forks back to back. Replant the best healthy pieces with a good root structure from the outside of the parent plant.

14. Maintenance of Perennial Borders Take this opportunity to also enrich the soil with additional organic matter. Take this opportunity to also enrich the soil with additional organic matter. A few plants do not like to be disturbed in this way, these include Peonies and Hellebores, these can be left alone. A few plants do not like to be disturbed in this way, these include Peonies and Hellebores, these can be left alone.