Plant Profiles Archives - Kilby Park Tree Farm

The Understated Elegance of the Olive Tree

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Favoured of course for it’s fantastic oil bearing fruit, olive trees also make a fantastic statement as a decorative plant.

No longer constrained to Mediterranean villas or humble farms, olive trees offer a modern simplicity to a whole range of landscapes and styles. Given a well drained soil, olive trees will flourish and add their distinct look to a garden for many years to come.

At present, Kilby has a variety of Olive trees on offer to fit the needs of your design, and we thought we’d feature our top 3. All feature the classic thin leathery leaf with a green top and silver bottom, with their own delights added.


Olea. a “kalamata” 

Known of course for it’s delicious fruit, the Kalamata is a smaller variety of the olive tree, growing 6 x 3 at maturity. Kalamata makes for a fantastic informal hedge or grove, and can be potted if well drained.


Olea e. ‘Tolleys Upright’

Mainly fruitless, this larger olive tree (7 x 4 at maturity) is ideal for urban landscaping as it tolerates dryness and pruning fantastically, offering the opportunity for screening. Fantastic for feature trees as well as creating privacy.

Olea europea ‘Nevadillo Blanco’

The Nevadillo Blanco offers you a similar option to the kalamata, with delicious fruit and a 6 x 3 growth at maturity. Leaves are slightly wider with an outwards spread, offering a different texture to the plant.

Consider adding the understated elegance of an olive tree to your next design.

Lovely Lindens, or Limes

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Tilia cordata is a lovely tree from Europe. In its natural range it extends from Northern Spain through to Norway, East to Russia and down through the Adriatic coast. Known as the Linden, Little-leaf Linden (as opposed to Tilia americana, which has larger leaves), or the Lime tree (no relation to the Citrus), the Linden tree has been popular in European landscaping for centuries.

In Berlin there is a famous street lined with Lindens – Unter der Linden – and it has long been used for street planting in Eastern Europe. It is a  favourite for creating large avenues, and in particular, for pleaching. Here is an example of a beautiful pleached walk at Arley Hall:


Lindens are valued not just for their beauty. Very fine honey is made by bees from Linden pollen, and the flowers are used to treat throat ailments. Lindens have fine, close grained wood, making them useful for intricate carving.

Lindens are not demanding in terms of growing conditions. They can cope with clay soils, though, like most trees, they thrive in good, fertile soils. They have moderate water requirements over summer, and will need additional watering on very hot or windy days.  They are moderate growers, and are easily kept tidy with pruning when they are shaped or pleached.

We are very excited to be offering these beautiful trees to our customers.

(photo courtesy of ClockPostcards)


Our newest variety – Zelkova serrata ‘Green Vase’

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This handsome tree is a native of Japan, Korea and Northern China. The species is used extensively in Japan for landscaping because of its elegant form, rich Autumn colours and toughness.

Zelkova serrata is a member of the Elm family, and it bears a resemblance to the American Elm.  The trunk branches low, and creates a broad, spreading crown. In the cultivar ‘Green Vase’ the form is more upright, giving a more vase-shaped canopy. The leaves flush out bright green in spring, darkening through summer, and in Autumn change to yellow through to russet red, depending on the conditions. With age the bark flakes to reveal reddish tones.

Zelkova’s are tough, tolerating compacted or clay soils, air pollution, wind and, once established, drought. They thrive in richer, moister soils, but will perform well in less-than optimum conditions. They will cope with light shade as well as full sun.


Kilby goes Jurrasic Park

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Visitors to Kilby will know we have our resident dinosaur, a Triceratops from the Late Cretaceous Period. Well, we now have another resident whose ancestors developed in an even more  distant times – Cycas revoluta.

The Cycad family are a fascinating group, who have been around in one form or another since  the Late Permian period 280 million years ago. Although Cycas revoluta is sometimes referred to as a ‘living fossil’, this is not strictly true. It is now believed that most modern forms of cycads have evolved in the last 12 million years or so, though the have not changed much in form since the first cycads appeared. There are two species of cycad in the family Bowenia that do appear to have survived unchanged since the Cretaceous period. Both of these live in Queensland.

Cycads are sometimes referred to as palms, though they are only distantly related. They arrangement of frond-like leaves on a single trunk is palm like.  The stiff, spiny leaves developed to make the plant less palatable to browsing by dinosaurs. There appear to have been many more types of cycads previously which have now become extinct. Possibly the cycads that are still around today are those that managed to evolve strong defensive mechanisms, such as the tough leaves, to survive the onslaught of hungry dinosaur herds.

In many ways they are still very simple trees. Cycads are either male or female, and pollination is carried out by wind or by insects. Both plants develop cone-like structures, the male ones looking a bit like a corn cob, the female are rounder.

Cycas revoluta is the most widely planted of the cycad family, and it is well suited to garden use. Originating in the Southern parts of Japan, it is tolerant of quite low temperatures (down to -10c), though very cold weather will cause it to lose its leaves. In Melbourne it doesn’t get cold enough to be troubled by leaf loss. Cycads love warmth, and thrive in sunny spots in the garden. Good drainage, and the application of mulch will keep them looking green and happy. Once established they can cope with drought, though they do better with good watering over the summer months.

Cycads are slow growing, and can grow to very old age. 1000 year old examples are known. Over time a trunk will develop, and often additional rosettes of leaves develop at the base of the trunk. These too will grow, and eventually you’ll have an amazing, multi-trunked cycad.

A couple of things to bear in mind when planted your cycads. The leaves near the base of the frond can become very stiff and sharp, so give thought to the effect on ankles of people when planting near paths. Also, although the leaves are tough and leathery, they can get frayed and untidy looking if continuously brushed against.




The trick to getting really green Gardenias

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A lot of our customers have noticed how healthy and green our Gardenias are recently. What is our trick?

Well, firstly, lets talk about why Gardenias sometimes aren’t green. Simply stated, it is a lack of nutrients, and is referred to as chlorosis. But simply feeding them will a general purpose fertilizer wont keep them from suffering. The story is a bit more complicated, involving both soil Ph and temperature.

Chlorosis occurs when the plant cant take up sufficient iron or manganese. Iron and manganese may be present in the soil, but when the Ph is over about 6.5, is not available for the plant to take up, leading to chlorosis. This can be overcome by using a fertilizer that has chelated iron in it. Chelated iron is iron that has been bound to another molecule, to enable it to be taken up by the plant, even where the Ph is above 6.5.

Temperature also plays a part as all chemical reactions slow down as temperature decreases. Even in soils that a moderately acidic, nutrient uptake can be too slow during cold weather to keep the plant looking healthy.

Because of this, gardeners in Melbourne are often advised to plant Gardenias in full sun, to keep them warm during winter. However, in warmer climates Gardenias thrive in lightly shaded positions, and in Melbourne in summer Gardenias can suffer from dehydration and scorch. Consideration should be given to finding a lightly shaded spot that could benefit from some extra heating.  Planting near to large areas of brick or stone can help, as these will absorb warmth from the sun and radiate it back out at night.

A lightening of the leaves is unavoidable in most outdoor plantings of Gardenias in Melbourne, but it is possible to still keep them looking reasonably good by using a targeted top-dress.  We use one that has a mixture of short and medium term release chelated iron, with other important trace elements such as manganese and zinc. An application of this in Autumn, and another in Spring, helps to fortify the plants and get them through the coldest months. We now sell this topdress in convenient 1.5kg bags. Contact us for more details.

Fiery foliage shows the beauty of Autumn

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After last Autumn’s fabulous show, this year’s display has been a little muted. the conditions that gave us such amazing colours last year – a wet summer, warm sunny Autumn days and cool nights – have not been repeated this year. However, despite the less-than-optimal conditions, one tree is still putting on a beautiful show. Acer japonicum ‘Vitifolium’ is a reliable Autumn performer, with a bonfire of colours at this time of the year. But it isn’t grown just for the fantastic seasonal colour – it is a valuable tree in the garden at any time. The large, grape-leaf (hence ‘Vitifolium’) shaped leaves are a beautiful light green in spring, darkening to a mid-green in late Summer, just before they turn the amazing mixtures of yellow, orange and red. It forms a mid size tree, tending to a broad spreading form, with a twisting trunk and broad, layered branches. Known as the Full-Moon maple, it is,  as the Latin name suggests, a native of Japan and Southern Korea.

Winning ways with Smoke Bushes

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The smoke bush – Cotinus coggygria – is one of the most beautiful of large bushes/small trees. The name smoke bush comes from the unusual flowering habit. Large inflorences develop in late spring, with many small flower buds. Most of these buds abort, and a small, feathery plume grows in its place. En-masse, these give the appearance of purplish-grey smoke. A large specimen can be enveloped in this ‘smoke’, which can be long lasting, and gives an unusual and beautiful display.

Cotinus can be vigorous growers, but the respond well to be pruned back very hard. Pruning will encourage the brilliant dark purple new growth of the purple-leaved cultivars such as ‘Grace’. If grown as a multi-stemmed bush, they can be pruned almost to the base. If they are grown as a single trunk tree, they can be pruned right back to near the base of the branches. However, be aware that Cotinus flower on second-year wood, so pruning a complete tree every year will mean that you will never get to enjoy the ‘smoke’. A good compromise is to prune back 1/3 or 1/2 of the branches each year. This will enable you to keep the tree in shape and still get to see the wonderful flowering display.

Cotinus lend themselves to a variety of different design styles. They can work well in slightly less formal situations, and look stunning at the back of a border. In Autumn the smokey flower heads look great, especially near dusk. One idea Heather came up with was to plant them behind a group of artichokes, the silver leaves contrasting with the purple. Large purple-flowered Alliums could be added to finish a stunning display.



We’re Pyrus-maniacs at Kilby

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Tough, adaptable and beautiful, Pyrus calleryana is a very popular choice for all sorts of different gardens. But what makes it such a good choice?

Well,  knowing where it comes from is the key. Although popular and widely planted in the US, Pyrus calleryana is actually a native of Southwest China and Northern Vietnam. It has a fairly limited range in these areas, and there is a lot of genetic diversity amongst the different populations, reflecting the different environmental conditions. How does that help it thrive in Melbourne?

The climate in Southwest China can be extreme. Long, hot, dry summers and short, cold winters. Sound familiar? Pyrus calleryana copes well with Melbourne conditions because it has evolved and adapted to similar conditions in its homeland. In fact, our winters are shorter and milder, which is why the tree is out of leaf for such a short time.

This toughness, ability to withstand dry heat, and hard winters lead to it being widely planted in the Eastern states of the US. An improved, more upright form was developed, called the ‘Bradford’, and to this day this name is used as a generic name for the species. However, the upright habit of  Bradford caused a problem with shedding limbs. Given the widespread use of it in street plantings, and the litigous nature of Americans, there was a need to develop a more  robust, yet still upright form. ‘Cleveland Select’, or ‘Chanticleer’, was the result of the programme to breed a better pear. It is now the leading form for use in gardens and street plantings, with a great combination of elegant, upright form and structural robustness.

An even more upright form is ‘Capital’. This lovely cultivar has a less even growth habit than ‘Chanticleer’, but it forms, in maturity, a narrow, upright tree of great beauty. A great choice when space is at a premium, it allows you to get the benefit of a tall, deciduous tree without the need to prune it back hard in a tight space. Popular for pleaching and hedging, it shares all the characteristics of ‘Chanticleer’ in terms of stunning spring flowering, deep, shiny leaves and outstanding Autumn colour.

Stunning Sioux

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You know summer is here when the Crepe Myrtles begin to flower. First up this year is ‘Sioux’, one of the smaller growing of the new ‘Indian Summer’ hybrids. ‘Sioux’ has clear, strong pink coloured flowers.

Like other Crepe Myrtles, Sioux has good Autumn colour. An added bonus is that the foliage of Sioux is bronzey when young, giving the tree a lustrous look. Sioux forms a small, dense tree, up to about 4m at maturity.

Sioux is truly a ‘four seasons’ tree. In winter, mature trees develop smooth, salmon coloured bark.The ‘Indian Summer’ range of Crepe Myrtles are derived from crossing Lagerstroemia fauriei, the Japanese Crepe Myrtle with Lagerstreomia indica, the Korean Crepe Myrtle . The Japanese name for this tree is saru suberi (literally “monkey slip”) which refers to the smooth, slippery bark. The ‘Indian Summer’ range of Crepe Myrtles are superior to the species in their mildew resistance.

Crepe Myrtles are becoming increasingly popular in Australia, especially where drought-tolerance is a key criteria for tree selection. They thrive in hot, sunny positions, though they will tolerate light shade. In fact there is a fine specimen opposite our Kew site which is under a large deciduous tree.

Crepe Myrtles can either be multi-trunked, or, when pruned accordingly, grown as single-trunk specimens.

Gorgeous Corymbias

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‘Flowering Gums’ are a feature of Australian culture as well as environment. Whilst all of the 700 odd species of Eucalyptus flower, when people talk of ‘Flowering Gums’, they are usually referring to Corymbia ficifolia. Corymbias are closely related to Eucaplytus, but are placed in their own genera.

Corymbia ficifolia is a magnificent tree. Native to a very small area just south of Perth, it has been planted extensively across Australia and worldwide. One of the reasons it is so much showier than other gums is that it flowers after is has finished its annual growth cycle, so the flower heads stay above the foliage.

Unfortunately, as a garden tree it has two major drawbacks; it is intolerant of anything other than well-drained, sandy soil, and it is very variable in colour. Seedlings can turn out to be any colour between cream and deep red.

In the last few years grafting technology has improved, and it is now possible to graft Corymbias. This means that trees can be produced with the certainty of uniform colour,  able to thrive in a greater range of soil conditions. Grafting has also allowed for the introduction of smaller-growing varieties.

Like many of the Eucalypt family, Corymbias have very attractive bark. Young trees have dark, coffee-coloured bark. This gradually peels to reveal a creamy-white bark.

We offer three different cultivars;

Wildfire, which is a rich vibrant red. This one has the classic red flowers, and grows to be about 6m x 3m at full height.

Calypso, a soft pink. This one grows to be a broad, rounded tree of approx 5m x 3m at maturity.

Baby Orange, a clear medium orange colour. This is the smallest of the three, filling out to a rounded tree of approx 3m x 3m at maturity. The new growth has an attractive orange tinge to it.