Q: What Does Perennial Mean?
A: Perennials are hardy plants that do not produce woody shoots. Most die down in the Winter and re-appear again in spring. Some are evergreen (Do not die down). They are generally planted in herbaceous borders but can be planted anywhere depending on their suitability. Some are alpine plants, others cut flowers. Some can be grown in shade under trees and shrubs and others in containers. They generally need little maintenance apart from keeping them weed free. They all flower – most of them between March an September, and provide colour year after year.

Q: Will these plants grow back again?
A: Yes perennials do grow back again. Care should be taken not to dig the ground in early spring where perennials are planted as they do come back in Spring. A few – like Papaver, Arum Lily, Cyclamen and Trillium die down in Summer and come back either in Autumn or early Spring.

Q: Do they need staking?
A: Some perennials do need staking – in particular many of those that are suitable for cut flowers. Give these plants a more sheltered area – not in the front of the border – to prevent staking as much as possible. Ensure that they are planted in a sunny position. Many perennials will flower again if old flowers are removed.

Q: How many do I plant together?
A: For impact small perennials should be planted in groups together. A mixed border (shrubs, perennials, bulbs, evergreens) is the most attractive way of planting. Depending on the size, we would advise to plant in groups of one variety:

•  Small Groundcovers:           5-12 Plants    i.e. Ajuga, Armeria, Lysimachia, Alchemilla.
•  Medium Sized Perennials:  3-5 Plants      i.e. Astilbe, Aster, Aquilegia, Coreopsis, Doronicum, Dicentra, Heuchera, Hosta, Papaver, Penstemon, Bergenia.
•  Tall Perennials:                    1-3 Plants       i.e. Acanthus, Kniphofia, Crambe, Phormium, Zantedeschia.

Q: What plants grow in shade?
A: Many perennials grow well in shade. For full shade we can recommend: Ajuga, Tiarella, Brunnera, Bergenia, Helleborus, Liriope, Polygonatum, Primula, Pulmonaria, Smilacina, Symphytum, Vinca, Trillium. Also nearly all ferns will thrive in shade.

Q: How do I maintain them?
A: Perennials are easy to maintain. Always keep the area weed free and cut back plants where they threaten to smother other plants. Apart from this, it is best to cut back spent flower shoots, this will encourage a new flush of flowers to appear. Any untidy parts can be pruned back before winter. Keep some of the growth though as it will protect the plants better over the winter period. Prune back further in spring if required when the new shoots start to appear. It is best not to dig the soil between plants. A top-dressing with a general fertilizer or mushroom compost will benefit growth in spring. In autumn plant early flowering bulbs between plants. This will give you added colour from February to April.

Q: When should they be trimmed?
A: Trim plants if untidy. Cut out spent flower shoots to prolong flowering. Tall straggly plants may be cut back half way in the summer so that they will bush out before winter. Cut back further in spring when the new growth appears.

Q: Can I grow them in pots?
A: A lot of perennials can be grown in pots. Use a good potting compost and ensure that plants do not dry out! Pots should be of sufficient size for the plant to prosper, generally 12 Ltr in size or larger. They need a drain hole in the bottom of the pot. Small perennials like Helianthemum, Campanula, Ajuga, Lysimachia, Heuchera, Grasses and Alchemilla can be planted together in one pot. Large perennials like Phormiums, Agapanthus, Beschonaria, Cortaderia, Fascicularia and Zantedeschia are best planted on their own to serve as focal points on a paved area.

Q: What colours should I plant together?
A: With colours you can create contrast or harmony. You can also use just one colour – say white – and contrast with the different shapes that flowers come in as well as using grey and silver leaved foliage plants with it. Good contrasting colours are yellow, orange and purple. Another is white, yellow, red and blue. Avoid using orange and pink together!

Q: How do I control pests and diseases organically?
A: There are many plant diseases and pests – but few cause a threat to the survival of your plants in general. Here’s how to control some of them in a biologically friendly way:

• Slugs and Snails: Clean off an effected area and sprinkle a barrier of wood pulp or sawdust around it. About one inch thick and four inches wide should do, or you can cover the full area with it at half an inch thickness. A sawmills or pet shop will have sawdust available. Used ground coffee can also be used. Lay this at the base of each plant.

• Vine weevil: Ask for nematodes in your local garden centre. This can be drenched into the ground to kill off the grubs. The beetle that hatches out of these grubs eats notches out of the leaf edges of plants that he favours. The larvae eat through the roots and may eventually kill some of your plants. Follow detailed instructions on the package.

• Aphids (Black Fly, Greenfly, etc): Remove worst effected shoots or spray with water with a few drops of washing liquid onto the plants. Natural occurring Ladybirds and Lacewing flies should be able to control the infestations after that. If a plant is badly affected persistently by aphids the most common cause is that the plant has not enough resistance to fight off the disease. This is caused by the plant being either unsuitable for the ground it is planted in or its position in the garden. Many perennials have less resistance if they are planted – say under trees – which causes drip on their leaves or drought because of their roots having to compete with the tree’s roots for water and food. Same may apply for leaf diseases like mildew and rust. It is important to choose the right plants for the right location. There are plants available for any location.

• Mildew and Rust: Mildew and rust is most common after periods of drought when the weather becomes damp again. Prevention is the best cure. Avoid that plants suffer due to stress caused by lack of water. So water plants in prolonged periods of dry weather. Effected plants will generally recover. Badly effected shoots can be cut out or the whole plant can be cut back after which the plant will develop healthy shoots again.

© Schram Plants 2009 Royal Oak, Moyvalley, Co. Kildare. E: info@schram.ie