Perennials
If you are looking for a beautiful flower display from spring to autumn, nothing beats a garden bed or pots full of perennials. Perennials are fast-growing, soft-wooded plants grown in gardens or pots for their long-lasting and usually colourful flowers and ability to grow year after year. Many are good for picking and highly attractive to beneficial insects.
Perennials are a diverse range of flowers that usually have a rhizome or bulb that fuels their growth. There are two broad types of perennials: evergreen and herbaceous.
- Evergreen perennials grow year-round and include favourites such as agapanthus, many daisies, lavenders, penstemons and salvias. Herbaceous perennials die down over winter and regrow in spring to flower in late spring, summer and autumn.
- Herbaceous perennials need lots of space to grow and develop. They are the flowering plants typically seen in perennial borders. Popular herbaceous perennials include peonies, sedums, asters, dahlias, chrysanthemums, helianthus, thalictrum, windflowers and dicentra.
Growing conditions
Aspect Most perennials need a bright, sunny location with sun for all or most of the day, but some perennials that thrive in the shade including hostas and thalictrum. When thinking about your selection of perennials to suit your location and climate, a visit to your local hardware or garden centre will be a great source of information. Horticultural staff can give you great information on types of perennials including colour, size and foliage.
Soil Most perennials do best with rich soil and good drainage. In areas with poor drainage, grow plants in raised garden beds (raised at least 30cm) or in large containers. Seasol Advanced Potting Mix is the perfect premium potting mix for perennials in pots and planter boxes. Alternatively, select perennials that tolerate poor drainage such as cannas.
Before planting perennials into garden beds, enrich the soil with homemade compost, organic matter and/or Seasol Super Compost. Use Seasol Super Soil Wetter & Conditioner where the soil is water repellent to ensure water gets to the plant’s root zone.
Climate There are perennials for all climates from cool to tropical, but traditional herbaceous perennials from the northern hemisphere grow best in temperate climates. Most herbaceous perennials are frost tolerant, provided they are dormant in winter and early spring. Late frosts can damage plants such as dahlias.
General care
Watering Once established, perennials are fairly drought-hardy but may need extra water when in they are bloom. Water more frequently if plants are in hot, dry or exposed conditions or growing in containers.
Feeding and mulching Herbaceous perennials should be fed as new growth resumes. Feed them with a liquid fertiliser such as PowerFeed PRO SERIES for Roses & Flowers every two weeks through spring until autumn until the flowers have finished. Heavy bloomers such as dahlias require regular feeding to keep plants blooming well. Supplement feeding with a granular fertiliser such as Seasol plus Nutrients for Roses & Flowers every 6 to 8 weeks to keep them looking good.
Mulch with organic mulch such as sugarcane mulch, pea straw or lucerne to aid soil moisture retention and keep weeds at bay.
Pruning Cut herbaceous plants to ground level in late autumn or winter. Evergreen perennials mainly need to be pruned to control their spread. Apply Seasol Plant + Soil Booster to the garden bed or pot to revitalise soil and plant health. Deadhead all perennials regularly and remove damaged leaves. Apply Seasol GOLD regularly to ensure optimum plant health.
Watch out As there is a huge range of perennials, there are a few things that can affect them, which will depend on their variety. Here are a few to watch out for:
- Humdity Plants in highly humid locations or that are not well drained may die back or be affected by disease.
- Cold Cold-sensitive herbaceous perennials may need protection overwinter from a covering of mulch or can be lifted and stored (for example, dahlias) to replant in early spring.
- Shade Plants growing in too much shade may be lanky or develop mildew.
- Pests Watch out for snails and slugs when new shoots appear in spring. Caterpillars may attack flowers. Dahlias can be attacked by earwigs.
- Plant growth As herbaceous perennials die down and disappear for part of the year it is important to mark where they are growing to avoid digging up or disturbing plants that are dormant.
