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9. Growing Hibiscus in Colder Climates

The secret of gardening is growing the right plant in the right place, and growing plants that do well in your particular area. However, human nature being what it is, the challenge to grow plants that are considered difficult in certain areas is very inviting. There is such a great feeling of achievement when one succeeds in growing and flowering such plants, especially if you live in a colder climate and the plants you grow are hibiscus.

In these cooler areas, hibiscus such as the syriacus types, herbaceous varieties and H. mutablis do quite well, however it is the evergreen rosa sinensis collection that is more attractive to the enthusiastic gardener.

Frost and cold winds are the main elements from which these plants must be protected. Providing protection from these will almost certainly ensure success, as long as the summers are sufficiently warm to promote flowering wood.

Of course, the blooms may not be of the highest quality, nor will the plants bloom for as long as they do in more temperate zones, but success is possible if a few simple basic procedures are followed.

Forget about planting hibiscus in the ground! The ground temperatures drop too low in winter, particularly where long, cold winters are experienced. Plant them in pots, preferably plastic ones, which retain more warmth than terra cotta or cement, and are a lot easier to handle. Don't use too large a pot; nice plants can be grown in 20 cm (8 in) to 30 cm (12 in) pots, and remember you are the one that has to move it around from place to place whenever necessary.

Use an open, free draining medium such as one part garden loam, one part peat moss, one part cow manure or mushroom compost and one part coarse river sand. Other mixes using perlite, vermiculite and other soil-less materials are equally as good. Sometimes it is a good idea to try out several mixes and use the one that suits your plants best, remembering that hibiscus are not too keen on mediums that contain high percentages of composted sawdust. Place plenty of drainage at the bottom of the pot to ensure free passage of water. Do not let these pots stand in saucers of water during winter. At the first signs of the weather getting colder, the plants should be moved to a more protected area, where they will receive plenty of winter sunshine.

Do not place them under trees. Although trees may protect hibiscus from frost, the cold shady conditions will do them more harm. The ideal way to carry plants over winter in cold climates is in a glasshouse, however these cost money and take up valuable space in the garden. The alternatives are a sunny room, or patio or verandah; remembering you are only protecting the plant until such time as the weather begins to warm enough to place the plant outside again. The advantages of a glasshouse clearly outweigh the disadvantages for the glasshouse could be used for plants other than hibiscus and a colourful display maintained throughout the year. These days there are many different types of glasshouses ranging from free standing pitch or gabled roofed types to the conservatory lean to type. Choose a type which will blend in with your landscape without distracting from the overall effect.

Do not position a glasshouse on the cool side of buildings. They must be placed in a position where maximum sunlight is assured. Glasshouses may be built from various materials, including glass, fibreglass and plastic. Choose the materials best suited to your requirements, remembering that with all glasshouses good ventilation is essential, particularly with plastic houses. The next best thing to a glasshouse is a sunny room, verandah or patio, where the temperature does not fall too low. Plenty of light is required to keep plants healthy, so plants need to be placed near a window where they can soak up the sun.

Fluorescent lights hung as close to the plants as possible without touching give glossier foliage and deeper colour to the blossoms. Blooms seem to last longer under the lights. Since hibiscus must have a great deal of light, the fluorescent lights will supplement the indoor light. Fixtures holding two 40 watt daylight tubes (daylight light is on the blue side) promote stockier, shorter stems which are desirable on the plants. The lights are used about sixteen hours a day. A single row of plants can be placed under the lights, using a 1 - 1.5 m (4 ft) long unit by a window for additional light remember, fluorescent light alone is not enough. You are only protecting the plant until such time as the weather warms sufficiently to return it outside.

When moving plants from a glasshouse or indoors to an outside position, it is necessary to harden off the plants otherwise scorching by direct sunlight may occur. This is easily done by placing plants in a shaded area and gradually easing them into more sunlight each day for several days, until the leaves begin to feel crisp.

Strong, healthy plants will withstand a greater degree of cold than weak specimens, therefore begin your collection with good plants at the start. Regular fertilising will build up the plants, making them sturdier and more resistant to the cold. Choose free flowering, hardy varieties to enhance your prospects of success. Plants grafted onto hardy rootstocks tend to tolerate cold better than ones on their own roots.

Make sure that your plants are outside and hardened off as the summer months approach. Plants in prime condition at this time will begin to produce buds in the warm sun. Even old pot bound specimens will bloom quite well, provided ample water and food is available during the flowering period.

Watch the plants closely for any pests or diseases which are attracted to soft, sappy growth common to plants grown under cover for long periods. If you have been successful growing tropical indoor plants in cold climates, then you should have no trouble with hibiscus.

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