Grevilleas – some of the myths exposed.
Grevilleas are a plant that have been used it gardens and landscaping for many years and despite this it still amazes me as to how many misconceptions there are about growing them, especially in the home garden.
They are a genus of plants that grow mostly on the continent of Australia and consist of well over 300 species as well as hybrids that number well into the hundreds. In fact the Grevillea genus hybridises so readily that horticulturalists for years have used the different species to breed new hybrids as well as using the hybrids themselves in the quest to breed new and exciting varieties that can be used both in the home garden and also for landscaping.
The species themselves though come from areas all over Australia from tropical rainforests that receive over 3000mm a year to deserts that receive less than 200mm. They can be found growing in soils that range from deep sands that are well draining to heavy clay soils that flood easily after it has rained so it would be safe to say that it is not really too hard to find a Grevillea that will suit any type of growing conditions that you might have in your home garden.
I’ve been growing Grevilleas in my garden for over 10 years now and have grown many different species and hybrids and have found them to be one of the easiest plants to grow that I have in my garden. There is just one rule that you need to follow. Know what your local climate and soil conditions are and select your plants accordingly. There is a grevillea for any place you might have in your garden no matter what your climatic conditions may be.
So here’s a few tips that you might want to follow.
Firstly if you come from a humid high rainfall area there are so many wonderful tropical Grevilleas available in nurseries today. G Banksii has been used extensively in hybridising many tropical Grevilleas and as a result there are hundreds of these spectacular hybrids to choose from. G Honey Gem, G Moonlight, G Pink Surprise, G Caloundra Gem and G Misty Pink are just a few of the very early hybrids that are readily available.
For those gardeners that think they have to put up with gardening in dry sandy areas then you may quite be the luckiest of all. Some of the most spectacular naturally occurring species come from the sandy arid areas of Central and Western Australia. G Juncifolia, G Petrophiloides, G Candelabroides, and G Eriostachya are just a very, very few of these fantastic plants. In some respects though these plants can be held responsible for the belief that grevilleas can be hard to grow. They have very specific soil requirements and when taken away from these conditions the plants tend not to survive. The other side of this though is that many of these Grevilleas can be grafted onto more reliable rootstocks such Grevillea Robusta, aka the Silky Oak and when done so they go from being very unreliable to being a lot more versatile but if you are lucky enough to live in a dry arid area with well draining soil then these plants will grow quite happily on their own rootstock.
I’ve also heard people say that Grevilleas don’t like to be cultivated around their roots and are intolerant of fertilizers that contain phosphorus. Both these comments are completely true. But can I say this. If a plant is has a root system that is so well developed so that it not only survives without fertilizer by actually thrives without fertilizer then why would you want to waste time and money cultivating and fertilizing anyway. Grevilleas are a member of the proteaceae family and as result their roots have evolved to survive in very poor soils and in fact this is one of the features of the plant that actually helps to make it such a drought tolerant plant.
Just one other thing about fertilizer though, if you are to fertilize, then it best to use one that is very low in phosphorus as it is the phosphorus that actually does the damage. A few years ago I accidently managed to contaminate my garden soil with phosphorus and as a result managed to kill quite a few of my proteaceae plants, of which quite a few were Grevilleas. This was a bit of a disaster at the time but the upshot of it all was that I soon discovered that not all Grevilleas were susceptible to phosphorus toxicity.
The ones that I found survived were Grevillea Thelemanniana, G Splendour, G Sea Spray, G Firesprite, G John Evans, a few of the G Banksii hybrids and those that were grafted onto G Robusta rootstock. So if you have a soil that has been fertilized there are few Grevilleas that will still grow in soil contaminated with phosphorus. Just one more tip, I’ve found that a high nitrogen liquid fertilizer can be used to counter the effects of the phosphorus.
Another misconception about Grevilleas is they grow very fast and die very young. The example that was being used was that of G Robyn Gordon a spectacular little hybrid that first came about in the late 1950’s. My mother has one of these growing in her garden that must be nearly 20 years old. It’s about 1.5 metres in diameter and gets pruned every year. Grevilleas respond very well to pruning and if pruned regularly and given the right growing conditions they will live as long as any other garden plant and in fact I’m lead to believe that the original plant that supplied the cuttings from which every other Grevillea Robyn Gordon has been propagated from is still alive today some 50 years later.
So in finishing I can only say that most Grevilleas are very easy to grow, some are fussy but remember most of these can easily be grafted onto more suitable rootstock. They are easy to maintain, just give them an annual prune and you should never fertilize them. If you do manage to contaminate them with phosphorus you may be able to undo it with some high nitrogen fertilizer. So apart from that all you need to do is leave them to do what they do best, put on a spectacular flower display and attract lots and lots of birds into your garden. So if you haven’t already got a Grevillea or two growing in your garden then give it a try.
Grevilleas really are very easy to grow.
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