Cooler nights signal the start of autumn garden work, from improving soil with fallen leaves to sowing sweet peas and planting hardy perennials, says gardening columnist JACKIE WARBURTON.
As the nights begin to cool, the last of the summer annuals and vegetable seedlings should now be in the ground or planted into containers.
March marks the beginning of autumn, when attention turns to improving the soil for the seasons ahead.
Over the next few months an abundance of leaf litter will fall into the garden. These leaves are extremely useful and make excellent compost.
Lightly spread them over garden beds, just enough to suppress weeds. In time the leaves will break down, enriching the soil and providing nutrients that support strong plant growth next spring. Good soil leads to healthy plants.
If there is a large quantity of leaves, they can be chopped with a lawn mower.
Larger leaves take longer to decompose, though the process can be accelerated over winter by adding other materials to enrich the soil. Products such as dynamic lifter, blood and bone, and most types of animal manures are suitable. A green manure crop can also be sown this month as a vegan alternative.
Where space is limited, a compost tower can be created, which also provides a small habitat for insects during winter. Any materials can be used to form a simple structure.
Stack leaf litter, twigs, branches and spent flowers inside. This sustainable approach gradually produces compost and, once the structure breaks down, it collapses back into the bed, adding valuable nutrients to the soil.
ONE of the most important jobs for March is sowing sweet peas. They take time to grow, so plant them near a path where their unusual, spicy scent can be enjoyed in late winter and early spring.
Sweet peas also make excellent small vase arrangements, with a fragrance that quickly fills a room.
To encourage even germination, seeds can be soaked overnight in tepid water with a little seaweed solution. When sowing, gently press the seed into the soil and lightly cover. Water in well, then wait until signs of growth appear before watering again.
Sweet peas grow well alongside nasturtiums, beans, sage and carrots, making them suitable for the vegetable patch. They flower in spring when pome and stone fruit trees are also in bloom.
Growth continues through winter, although it may slow once the soil becomes very cold, before surging again in spring to produce a mass of flowers.
Dwarf varieties such as Bijou do not require a trellis, though they benefit from light support or being kept off the ground.
ANOTHER plant suitable for planting now is Aquilegia, commonly known as Columbine or Granny Bonnet. This short-lived perennial tolerates frost well.
Aquilegia caerulea forms a small shrub that requires little water or care once established.
The flowers appear in a wide range of colours, including many striking multi-coloured forms. Foliage spreads to cover the ground during winter, while flower spikes rise above the leaves in spring. Removing spent flowers encourages further blooms.
Some aquilegias self-seed and fill gaps in the garden. If too many appear, small seedlings can be removed by hand. Larger plants may be divided and replanted or transferred to containers to give away.
They can also be grown from seed. Sprinkle seed lightly over seed-raising mix, then water gently. Keep the mix moist during germination. Once seedlings are large enough, plant them out in the garden. They prefer acid soil and pair well with camellias and azaleas.
OPEN Gardens Canberra’s autumn gardens are open and this time there’s an opportunity to see the hard work of gardeners in Yass, Calwell and Hawker. More information at opengardencanberra.org.au
Jottings
- Cut winter iris to the ground.
- Remove old leaves from hellebores.
- Spray stone fruit as the leaves fall.
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