Like people, plants all react differently to the heat. Some plants relish it - the hot days really encourage a spectacular flowering in plants such as bougainvillea, mandevillea, silk trees, jacarandas, petunias, impatiens, flame vine and tropical hibiscus. It is during these hot months that these plants really come into their own. Other plants don't react well to the heat; hellebores, Chatham Island forget-me-nots, rhododendrons, azaleas and camellias can all end up with scorching on their leaves if they are overly exposed.
At the same time, for many plants, if they can be kept moist during the summer months it is the time that substantial growth can be made. If you are growing plants to create privacy then ensuring they are well watered and well fertilised during the summer months will encourage much faster growth than during cooler times of the year. Plants such as pittosporum, griselinia and many other natives, evergreens and deciduous trees will react in this way.
A way to help plants during the summer months is to mulch the soil around them. Mulching is the spreading of a layer of organic matter on the surface of the soil with the aim to improve moisture retention, improve soil fertility and structure, provide a cooling effect on the soil and root system below and suppress weeds.
If you are looking at doing some major planting in the autumn then mulching an area during the summer is a way to start improving soil structure and encouraging earthworms and microbial activity, giving better results later when plantings are going to be made. As the saying goes, "the answer lies in the soil" in regards to success or failure in the garden. If you have seen the growth that can be achieved, particularly in Taranaki soils or Westmere loam, then you will agree with this statement!
There are a number of different mulches available that will best suit different plants and soil types. At the garden centre we have bulk landscape supplies of these and other products and it has been an interesting exercise to source and develop products suitable to specific plant types and categories.
Some of the options available for mulching are Poultry Compost, Natural Bark Feeding Mulch, Arborists Mulch, Mushroom Compost, Peat Moss and Pea Straw in bales and bags.
Hibiscus, Summer Delight
Hibiscus is amongst the most favoured shrubs for tropical, subtropical or warm temperate gardens. In Whanganui some grow more vigorously and bloom better than others. In selecting hibiscus keep an eye on nearby gardens to you for robust, free flowering plants to give you an idea to obtaining good plants for your situation.
Some early references claim the geographical origin of hibiscus rosa-sinensis, which literally means "Rose of China". Various forms eventually found their way to England. Others suggest it hailed from India. Captain James Cook and other Pacific explorers later found a double red form being cultivated in several island groups. Early botanists suggest Polynesian migrants may have brought hibiscus with them from South East Asia and then to Hawaii, Tahiti and Fiji.
The story goes that a bloom worn over a girl's right ear could suggest that she's in search of a mate, while over the left ear indicates mission accomplished. Hibiscus became the national floral emblem of Hawaii in 1923. The history and legend is somewhat fascinating and I hope it serves as an introduction and appreciation of the diversity of form, colour and sheer beauty of hibiscus flowers.
Earlier crossing of Chinese and native Hawaiian species has resulted in the development of most of the thousands of hybrids grown today. If you enjoy hibiscus, I encourage you to find space for one more. If you are just beginning and have yet to experience the delight of picking a hibiscus bloom from your garden this will be one of the highlights of your gardening life.
There are a few different hibiscus types that are available to home gardeners today.
Fijian Hibiscus - Cold hardy shrubs that normally retain their leaves during winter. Blooms are slightly smaller than Hawaiian, but the shrubs tend to be larger. More solid colour shades.
Clarks Hybrids - New Zealand bred varieties by Jack Clark that are ideally suited to temperate conditions. They are a cross between Fijian and Hawaiian hibiscus.
Hawaiian Hibiscus - These are smaller growing, cold tender shrubs with huge flowers, they like to be grown in a warm, sheltered and sunny spot. The varieties come in multi colours of almost every shade except blue.
