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Floods and Your Garden

Starting again after getting submerged


Many gardeners face the enormous job of clearing out flooded gardens this weekend. Past experience tells us the plants that are likely to survive and the tasks to prioritise when tackling the clean-up.

Collect fallen branches and rake up leaves and twigs from grass areas. Clean mulch that has washed up against tree trunks. An important step in aiding the recovery of treasured garden plants is to remove any mud and silt caked thickly onto the stems of branches or built up over the roots.

It is important to do this as quickly as possible as it is easier to hose off while it is still wet. Once dried the task becomes much more difficult. The soil in the gardens that has become completely submerged quickly becomes anaerobic and it is this lack of oxygen that cause plant roots to die.

Grevilleas, wattles and most banksias cope poorly with prolonged inundation. Pawpaws, passionfruit, citrus, frangipani and many fast-growing climbing vines are also prone to root rot. Sudden wilting and tip dieback are often the first signs of serious problems. Expect to see increased bud drop on camellias and fruit drop and split fruit on productive trees over the coming season.

Take cuttings of what remains of fast-growing plant like salvias, dracaena cordylines and tropical species. Cut cannas, heliconias and ornamental gingers to ground level and allow them to reshoot. Large palms that have been blown over by the wind can often be pulled upright and saved. Even those toppled by fast flowing water are worth salvage attempts.

Soft-wooded trees like poinciana and jacaranda are prone to failure. Keep a careful watch on then in the coming months as it can be some times before mature trees fall victim to decay. Vaegetable crops and flowing annuals pummelled by dats og constand rainfall are best removed and composted. It is likely they will soon turn to mush if they have not already done so.

Aerate the soil using a garden fork and allow time for the soil to breathe before attempting any replanting. Seaweed is a great tonic to repair damaged root systems and ward off fungal root disease. It is also a great tonic to repair damage to soil structure done by seawater inundation and swimming pool overflow. Apply each week until plants show signs of recovery.

Liquid silica and potassium (Plant of Health range) are effective in both combating root disease and fungal problems affecting plant foliage. Beneficial trichonderma fungi (used by professional arborists as liquids and pastes) and biodynamic silica sprays are more difficult to obtain, but may also be used.

Annette McFarlane, 2013, “Starting again after getting submerged”. Courier Mail, 3 February, pg. 56. Homeground

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