A week of rain showers and grey skies in Whanganui has been a boon for the garden. It has boosted soil moisture levels as we head into December and the official start of the traditionally drier summer months.
The benefits of regular watering during the summer months were demonstrated throughout much of New Zealand with the wet summer last year. Around our fair city, the growth on trees in parks and gardens was quite phenomenal for the observant to see. I would estimate many plantings achieved growth during that one wet summer that would have taken two to three drier years to achieve.
Such growth can be achieved in the home garden every year through thorough, deep watering weekly in the evening. Combine this with warm summer temperatures and a recipe for establishing a successful garden is well under way.
Now is a good time to mulch exposed soil areas with products such as bark chips or nuggets, pea straw or bagged products like Tūī Mulch & Feed. Mulch will help the soil retain moisture from rainfall and provide the soil protection from direct sunlight, which reduces moisture evaporation. Your plants will thank you for this with stronger growth and establishment. It is also worth noting plants that are well-fed and watered see significantly reduced incidences of attacks from pests and diseases.
Hydrangeas have surged in popularity in recent years. They are on trend as classic, no-fuss plants from yesteryear. Their large, full, lush blooms carry happy memories of our grandparents, who also loved them. They are reproduced as faux flowers as well as dried and dyed for year-round displays indoors in public places and modern interior decorating around the home. Freshly picked in a vase, they last well, too.
In the garden, hydrangeas are star performers during the summer months. The blooms start in late November and carry on through Christmas and into January and February. Some have blooms that will stay on the plant into the autumn months, changing colour to antique shades as the flowers age.
The most familiar hydrangeas are “macrophylla” hybrids, meaning they have long or large leaves. The bold heads bloom in white, pink, red and blue in the summer. The macrophylla types include “mophead” and “lace cap”’ forms.
The mophead is recognised as the “classic” hydrangea, with a rounded flowerhead; the lace cap has a flatter flowerhead with florets around the blooms, while the centre has the appearance of an unopened bud.
There is another range of hydrangeas, “paniculata” varieties. These plants flower later, with blooms generally starting in December or January. The paniculata types carry on until later in the season, with blooms still coming on in March and April. The blooms start off white, then develop varying colours according to their varieties, which are unaffected by soil pH.
Although many hydrangeas can exist with little or no attention, they do respond positively to extra care. The flower colours can be controlled and intensified and the blooms greatly enlarged with feeding and annual pruning.
Fortnightly liquid feeding now during the growth period, after the flowers have formed, will encourage enormous flowerheads. Hydrangeas vary in flower colour according to soil acidity or alkalinity. Blue colours require acid soils; this can be created, if it doesn’t occur naturally, with applications of aluminium sulphate at monthly intervals during the winter months and prior to flowering.
Red and pink colours occur in alkaline soil situations. Applications of garden lime will make the soil more alkaline to keep these colours vibrant. These pH-adjusting products are available in the garden centre in both liquid and powder forms.
The white flowers stay true to name in both acid and alkaline soil situations.
Some brilliant hydrangea varieties include:
Hydrangea Bridal Bouquet - This mophead form has pure white blooms; grows around 1m by 1m.
Hydrangea Renate Steiner - A strong blue mophead form; grows around 1m by 1m.
Hydrangea Raspberry Crush - Also known as “Merveille Sanguine” and “Bloody Marvellous”. It’s one of the darkest reds available in a hydrangea, with foliage that follows suit. It produces masses of blood-red, mophead flowers in ball-shaped clusters. Deep, dark green foliage takes on a heavy maroon tone which intensifies through summer. Grows around 1.5m by 1.5m.
Hydrangea Strawberries & Cream - This flower puts on a spectacular show, with lace cap blooms contrasting between red florets and cream centres. Grows around 90cm high and 120cm wide.
Hydrangea White Wave - A lace cap form with white florets surrounding a white centre with blue tinges, highly attractive. Grows around 2m by 2m.
Hydrangea Harlequin - A mophead hydrangea which has striking two-coloured blooms. The flower clusters are large, with cerise pink florets edged with a thin band of white. The petals are also a touch more pointy-edged than usual mopheads. An unusual and striking combination. Grows to around 120cm. Perfect for shady spots.
Hydrangea Goldie - A superb plant to lift a shady area with gold-green-coloured leaves. The white mophead-type flowers make for an attractive show. Grows around 1m by 1m.
Hydrangea Limelight - A paniculata variety producing masses of lime-green flowers through the summer months. An amazing display of flowers in the heat of summer. Grows around 1.2m high and 1m wide.
Protect against insect pests
The warming temperatures that are promoting good growth in the garden are also resulting in a rapidly expanding population of aphids, whiteflies, caterpillars, scale, potato/tomato psyllids and other attacking insects.
The effect of psyllids on potatoes and tomatoes is completely devastating. These crops should be sprayed now with the bee-friendly insect spray Yates Mavrik. This spray works on contact with the insect. This means that to break the life cycle of an infestation, a few sprays in quick succession will be needed to knock back the population. Follow all packet directions carefully when spraying pests and diseases. Care should be taken so the spray reaches both sides of the leaves to get an effective result.
An organic product, Naturally Neem, can be used for aphids, whiteflies, thrips and mealy bugs.
I recently read a recommendation which said mixing these two products will have a good effect. Mavrik works by contact and ingestion, while Naturally Neem stops feeding and disrupts the breeding cycle. A mixture of Yates Mavrik with Naturally Neem offers a two-pronged attack, giving particularly effective results. This combination works on all chewing and sucking insects. Once the spray is dry, it is bee-safe. It can be used on vegetables and has a three-day withholding period.
Combat 3-in-1 for Roses is a good rose spray. Combat is the only three-in-one spray - insecticide, fungicide and fertiliser - especially made for roses. Combat is marketed as a rose spray but is also suitable for other ornamental plants. This weather has been great for bugs - beat them to the draw with Combat.
Another range of products that has recently come to my attention, particularly for the treatment of psyllids on potatoes and tomatoes, is the Wally’s range of silicon products. They work by making the plant’s cells too tough for the psyllid nymphs to pierce and feed from - definitely something to try in the battle against these destructive pests.
For more gardening information, visit www.springvalegardencentre.co.nz.
Gareth Carter is the general manager of Springvale Garden Centre.