Heat wave first aid

A lot of Australian gardens are suffering from a prolonged spell of very hot dry weather.
Garden beds that contain a moderate amount of organic matter will handle the extreme conditions better than most, as organic matter in soil keeps soil more moisture retentive, especially if mulch is also applied to the soil surface.
• Avoid watering in the middle of the day. Water early or late in the day. If watering in the afternoon, first check that the water in the hose has not reached a temperature that will scald plants.
• Try to give vegetable beds and precious shrubs a deep watering rather than a light daily hosing, and only repeat watering when the top cm. of soil becomes dry. Daily hosing usually only wets the top centimetre, or so, of soil, encouraging plant roots to stay close to the soil surface, making them more prone to wilting in hot weather.
• Apply a thick layer of mulch to all beds, if possible, as this will prevent loss of soil water through evaporation. However, avoid mulching beds close to buildings in areas where bush fires are a risk.
• Provide a temporary shade canopy for beds or plants that appear stressed. Use whatever is available – shadecloth, tarpaulins, old curtains, etc. Shading them will reduce water loss through the plants’ leaves, and plants will require less watering. Plants release moisture through their leaves in an effort to keep cool, in a similar way to our perspiration.
• If possible, move potted plants and seedlings against the south side of a building, where it is cooler. The mix in pots can become much hotter than soil in beds, and potted plant roots can become permanently damaged in this type of weather.
• Place pots close together as they will create group humidity, keeping them cooler.
• Avoid fertilising in this weather, unless it is seaweed tea applied after a deep watering. Fertilising when soils dry out quickly increases the risk of fertiliser burn and makes plants less able to cope with adverse conditions.
• While you can leave burnt foliage on plants and the plant will usually recover when temperatures cool and watering is adequate, if a favourite evergreen shrub or citrus tree is extremely distressed, prune it back – leaving some foliage so that it can manufacture food. This can help the plant to provide water more efficiently to the remaining plant. Leave the prunings as mulch around the base of the plant. However, pruning of deciduous plants at this time of year can cause excess sap loss (bleeding) in some varieties, such as grapes, pecans, mulberry.
• Give flowering annuals lower priority if water is restricted – these can be easily replaced when conditions are more suitable for growth.

3 thoughts on “Heat wave first aid

  1. I will take note of these points in the next hot spell- I didn’t know that about fertiliser. I did put sheets over our cherry tomatoes and pea plants and they all seem to have survived quite well. We are on water restrictions that allow 2 hours of watering per week, total. I save every drop of clean water from the house (cooking water, dregs of drink bottles etc.) and we have managed to start a vegie garden.
    Great blog!

  2. I have mulched with pea straw round things like corn etc. I was wondering should I do the same with lettuce etc. I
    have not long planted some new ones of spinach and lettuce but of course they are feeling the heat so should I mulch
    tham also?

    We mulch all vegetable beds in our area Michelle, as it reduces water evaporation from soil and saves water. Mulch is essential in this type of weather, and I’d also give your plants some temporary shade as lettuce and spinach are quite sensitive to excess heat. – Lyn

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