Wally Richards – watering & other autumn issues

It is Easter Saturday as I write this column, (I normally always write them on a Saturday morning each week) and for the last 3 days I have not watered any of my gardens or container plants – including those in my glasshouse.



This is not because we have had lots of rain, in fact it has only rained once, a couple a nights ago. It is because the soil in all situations, including the glasshouse, is still moist from the last time I watered or it rained.

I checked all the garden areas this morning as I was collecting vegetable leaves to make my Green Smoothies. The surface of the soil (compost) was dark in colour, indicating that there was still a good moisture content. All the plants were happy with no sign of water stress, so the best bet is just leave them till they dry out further. Even in the glasshouse where I have several tomato plants and a watermelon for winter cropping, the same applied.

I learnt a long time ago that over-watering at the change of seasons and through the winter is dangerous to plants in containers in the glasshouse and outdoors. The much cooler temperatures reduce evaporation and plants do not need a lot of water, in fact they prefer their roots in a drier, just-moist situation. Sometimes in the past I have made the fatal mistake of watering every day without considering how moist the soil or growing medium already is. When I have neglected this important aspect I have lost plants left, right and centre.

Excessive water in the medium means two things: it increases the ‘cold factor’ (just as we notice that if we have wet hands on a cold day they will be colder than dry hands); and leads to rotting of the roots and the demise of the plants. Outdoors in the garden we cannot control the amount of rain that falls on our gardens, so plants such as citrus can suffer when the soil becomes too wet. On the other hand, containers with sensitive plants growing in them can be moved to more sheltered spots where they do not get rained on. Any saucers under the containers should be removed and the containers lifted slightly off the ground by placing a couple of slats of wood under them. This allows an airflow under the pot and keeps the drainage holes free to operate.

In open garden situations a trench dug just outside the root zone around your citrus trees for example, will assist surplus rainwater to drain into the trench where it will evaporate faster with sun and wind. The more rain in winter, the greater the drainage problem becomes to plants sensitive to wet feet. Wet weather diseases often take the lives of plants in winter if one is not careful. You can help prevent the problem by a monthly spray of Perkfection Supa over the foliage. This fortifies the plants and assists in the prevention of root rots.

Preventing winter losses
Another problem with increased water, is that mulches applied over the summer months to retain moisture levels in the soil, now become dangerous around wet sensitive plants. These mulches should be raked back, away from the root zone so the soil can breathe freely. Gardeners should be aware of these potential problems and take the necessary precautions now. A little care now will reduce the number of plants you may need to replace in the spring.

Plants need to be hardened up to face winter better – applying potash is a good way to help them cope. Also a lack of magnesium during the cooler months causes yellowing of leaves. To overcome both these problems, a monthly application of Fruit and Flower Power can be applied to the soil – as the product contains both potash and magnesium.

Frost protection for tender plants is another winter problem, and a spray over the foliage using Vaporgard will give your tender plants protection down to minus 3 frosts for 3 months within 3 days of application. This works a treat for the occasional frost, but if there is a series of frosts, day after day, then additional protection should be applied such as Frost Cloth.

Pests that have plagued your plants over the previous months will be disappearing now as the cooler weather takes over. Hopefully a good hard winter will kill many. The more that do not survive winter, the less there will be to start breeding when the spring comes.
You can also assist in reducing their numbers now by using a couple of sprays, about a fortnight apart: Neem Tree Oil and Key Pyrethrum. In the spring, as soon as the first pests are noticed – repeat the sprays. Early prevention can make for less problems in the summer months.

For the lawns there are two aspects to consider besides any patching or re-sowing.
Thatch, which is the debris that builds up on the soil surface and causes harm to your lawn should be treated with Thatch Busta to remove. Porina caterpillars will be active at this time eating at the base of the grasses when they emerge in early evening. To fix this problem, mow the lawn then apply Neem Tree Oil as a spray or by using a Lawnboy. The trick is to get the oil to the base of the grass where the catapillars will consume some, never to eat again.

The larva of Grass Grubs or Black Beetles will also be in some lawns near the surface eating the roots of your grasses. The first step is to lift some turf and check for infestation numbers. If only the odd one or two is found at any test spot, then they will not do sufficient damage to warrant treating. If a good number is found at a test spot, then treatment in that area should be applied. Areas to check are where previous damage has been done, and also areas that are near night lights and street lights as the beetles were attracted to those spots when on the wing. There are two treatments that can be used; one a chemical called Lawn Pest Control which I do not advise if you don’t like chemicals or have pets. The second is a natural one called Professor Mac’s 3 in 1 for Lawns. Very safe to use and deadly on grubs and Porina.

If using either of these two treatments, then the Neem Oil would not be needed for Porina. If only small areas need treating for any of these lawn pests then a sprinkling of Neem Tree Granules can be applied. Mosses will also start to appear in lawns and other areas, Spray them now with Moss and Liverwort Control. Being winter-ready in your gardens is an important part of gardening at this time of the year.

Any problems ring me at 0800 466464 (Palmerston North 3570606) or email

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