Bulbous Plants
Posted by Phytopath on May 21, 2011
The tern ‘bulb’ is frequently used to describe plants that have underground storage organs.
The categories used to describe these plants are: – bulbs, corms, tubers, rhizomes or tuberous roots.
Correct identification of the storage organ is important if you are planning to increase the number of plants through propagation.
A true bulb is made up of leaves and petioles (the stalky bit at the end of a leaf) that have been modified and
these leaves are attached to a base plate.
If you cut an onion (true bulb) in half, the concentric rings that can be peeled away are the modified leaves and the solid bit at the bottom is the base plate.
Other examples of true bulbs are: – daffodils and tulips.
Another type of true bulb with a different appearance is a ‘scaly bulb’, sometimes also called a non tunicate bulb.
These bulbs do not have tight concentric rings or a protective tunic (the papery bit of the onion). Two examples of non tunicate bulbs are Lilium and Fritillaria.
Corms are solid inside, unlike the concentric layers of bulbs.
New growth arises at the top of the corm, unlike bulbs where new growth happens at the base plate.
The nodes and internodes occur on the outside or exterior surface of the corm. New cormlets (babies) can develop here and take two or more seasons to flower.
Examples of corms are Gladiolus, Freesia and Watsonia.
When selecting bulbous plants to grow in the garden, the two most influential factors are rainfall and temperature.
There are five broad climatic zones where bulbs are found growing.
- Winter rain and cold winters (-24° to -8°C and 27° to 37°C)
- Winter rain, cool to mild winters (-5° to 4°C and 28° to 38°C)
- Summer rain, cool to mild winters (-1° to 22°C and 30° to 35°C)
- Year round rain, cold winters (-20° to -8°C and 26° to 35°C)
- Year round rain, cool to mild winters (-8° to -3°C and 24° to 34°C)
Some gardeners live in areas that can restrict the selection of bulbous plants that can be grown.
These may be: -
- Lack of winter chilling
- High air and soil temperatures
- Low annual rainfall and high evaporation rates
- Generally poor soils
You are likely to find a bulbous plant to suit most situations or positions in the garden.
Whether it be full sun or dappled shade, sandy soil or heavy clay.
They are a versatile group of plants and can be grown in containers as well as in the garden.
Hoya carnosa
Posted by Phytopath on Jan 15, 2011
Hoya is also known as wax flower and is a member of the Asclepiadaceae family.
Many of the Hoya species are root climbers and twiners with thick, fleshy succulent leaves.
The plants have a broad distribution from China to tropical Australia.
They generally inhabit rainforests but one species – Hoya australis (syn H. oligotricha), can be seen growing on rocks, close to the ocean and exposed to salt spray.
In the home garden, they are usually found growing under the patio or pergola, or in a bush house. The most commonly grown species in southern states of Australia is Hoya carnosa (see picture above).
This plant is a native of Southern China and Eastern India and has a twining habit and thick fleshy leaves to 9cm long. It is an evergreen plant and the leaves are dark green and ovate in shape. The overall length of the stem is around two metres long.
Bright light is a must for good growth and this species can tolerate some sun: early morning is best, but protect from too much sun, frost and wind.
Fibrous, humus-rich soil is best for growth but most plants are grown in hanging baskets using a good quality, standard potting mix. The essential requirement is good drainage.
Water the plant regularly during the growing season and greatly reduce the frequency and amount of water during the cooler winter months.
The flowers are thick and waxy in texture and appear in summer. The umbels of scented, pink, star-shaped flowers cascade in dense trusses along the length of the stem.
If the plant roots are confined and not disturbed, there is a good chance that the plant will produce more flowers.
These flowers are not for picking however.
The flowers arise from permanent stubs each year, much like spurs on a fruit tree. So if you remove the flower stalk with the flower attached, then you will be removing future flowers as well.
The seed pods of the Hoya are long and cylindrical, 
and the mechanism for distribution is the wind.
The actual seed and dispersal ‘fluff’ attached to it, look very much like dandelion (see photo).
Hoya can be propagated from seed or stem cuttings. If taking cuttings, do it in summer and include two nodes.
Fertilise the plant once or twice during the growing season, but do not overdo it.
There are variegated leaf forms of Hoya available, and also a form called ‘Compacta’ which has twisted, contorted leaves similar in appearance to the plant called snail creeper.
In conclusion, if you supply the plant with cramped growing conditions, forget to fertilise it, remember to water it only occasionally and don’t touch it – it will most likely reward you with a beautiful show of flowers.
Growing Hippeastrums
Posted by Phytopath on Dec 7, 2010
Hippeastrums, frequently referred to as Amaryllis in the Northern hemisphere, are a group of bulbous plants with showy flowers, mostly from South America.
Hybrids of Hippeastrum equestre were introduced into Holland around 1700 and the first commercial attempts at hybridising were carried out in 1799 between Hippeastrum reginae and H. vittatum.
The best named varieties produce up to four large, brightly coloured trumpet or funnel shaped flowers that are 15-20cm (6”-8”) across on tall stems that are about 50 to 60 cm (24”) high.
Because the stems are quite tall and because they are hollow, protection from strong winds is advisable.
The flower buds and stems grow from the side of the ‘neck’ part of the bulb and the showy flowers appear in late spring and summer. They are flowering here (Southern hemisphere) now.
There are many hybrids and cultivars available today, some even have double flowers.
The typical flower colours available are various shades of red/crimson, orange-red, fire engine red, (great at Christmas time)red and white striped, pink, white and a long time favourite, – Apple Blossom, which is white with pink stripes.
When planted in groups or on masse, they are a real eye catcher.
Hippeastrums can be manipulated to flower at Christmas time, in the Southern hemisphere, by placing the bulbs in the refrigerator at 5 degrees C until mid November.
They are then removed from the fridge and planted in the ground or in a pot when the temperature is around 20-25° C. This change in temperature should initiate flowering.
The flowers should appear approximately five weeks after planting out or potting up. If the flowers are developing too quickly, move the plant (if it is in a pot) to a cooler location. This should slow flower development. Conversely, if the flower buds are taking too long to mature, move the pot to a warmer location.
Hippeastrum flowering times are very closely related to temperature.
Once the individual flower buds have separated, it will take about three to four days for them to open.
The best growing environment for the bulbs, is an area where the soil is well drained, has had some organic matter added – like animal manure, away from strong winds, with plenty of sunlight if you are growing them in a cool temperate climate or in dappled shade if you are growing them in a warm temperate to desert type climate.
Plant the bulb with the ‘neck’ protruding above the soil. At least one third of the bulb should be above the surface of the soil. Water weekly during dry spells in the active growing season.
Some hippeastrum bulbs are evergreen and some are deciduous.
Many gardening books tell you to lift and store the bulbs over winter. Personally, I think it depends on your soil type and climate.
I have not lifted my bulbs in over 20 years and they are multiplying and flowering nicely.
The plants can be propagated by division of the bulbs in autumn or by bulb scaling which is used in commercial production. You could also have a go at propagating them by seed. You might just come up with a wonderful new variety.
Grevillea robusta
Posted by Phytopath on Nov 15, 2010
Grevillea robusta is locally known as Silky Oak. It was given this common name by pine cutters who thought the timber resembled English oak and also noticed that the timber was silky when newly split.
The species name robusta, comes from Latin robustus, which refers to the stature of the tree.
It grows naturally in southern Queensland and northern New South Wales, often found along creek and river banks.
Large numbers of trees were planted in Hawaii and South Africa. In Uganda and East Africa the tree is used to shade coffee plants.
The tree can grow quite fast and tall, up to 35 metres, with a straight trunk. Once mature it has a somewhat pyramid shape.
Because of the fast growth and the showy flowers in spring, the tree has been a favourite for avenue planting where space allows it. For most city back yards the tree is considered too large.
The leaves are fern-like in appearance (pinnately lobed with secondary and tertiary lobes, see pic) and light green in colour on the surface with a lighter coloured underside. They can be up to 30 cm (12”) long and the reason for the lighter coloured underside is the fact that they are covered with silky hairs.
If the tree is under stress at any time, either from cold or drought, it has a tendency to drop its leaves.
The flowers, when they appear, are spectacular. Each raceme is up to 12 cm (5”) and each flower is about 10 mm long. The style is about 20 mm long, brightly coloured and remains after the perianth has fallen. In plain English, they are toothbrush-like, shaped flowers, bright gold/orange in colour.
The flowers produce copious amounts of nectar and the tree is an excellent bird attractor. Not only honey eater birds and parrots are attracted to the volumes of nectar, but bees are also lured into the mass of golden flowers.
What a wonderful tree to have in the garden. It has the ability to draw birds and bees from far and wide, and once in the garden they can also visit other plants, to pollinate them.
Gardeners who grow this plant as an indoor specimen, (UK and Europe), sadly, never get to experience the beauty of this tree in flower.
Many Australian publications on ‘Bush Tucker’, note that the Aboriginal people made a drink from the flowers or sucked the nectar straight from the flowers, reported to be high in vitamin C. The University of Queensland Botany Club, also mention a palatable drink can be made from the nectar rich flowers. However, in 1930 a mixture of pistils, capsules and seed were tested by Smith and White and found to have a positive cyanide reaction. I am not aware if this test has been repeated. All I can say is, proceed with caution.
Grevillea robusta is a very hardy tree and because of its hardiness, it has been used extensively as a rootstock for less hardy species of grevillea as well a rootstock for weeping standards. To produce a weeping standard grevillea, allow the rootstock (Grevillea robusta) to grow to about 2 metres (just over 6 feet) or any height you want really and then graft a prostrate species on top.
If you would like to experiment with a weeping standard, find someone in your neighbourhood who has a Silky Oak growing. Knock on their door and ask politely if they have any young seedlings available that you might be able to use. I can almost guarantee that they will welcome you in with open arms, because the darn things seed so prolifically that it is almost a pest plant (in the right climate). Be warned.
In My Garden – late October
Posted by Phytopath on Nov 1, 2010
Strolling around my garden between showers of rain, I thought a series of photos showing various stages of flower development on Grevillea ‘Moonlight’, might interest you.
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Grevillea ‘Moonlight’
also known as Grevillea ‘Edna Ellen’
Raised from seed in Proston Queensland, Australia.
A shrub growing 3 or 4 metres high and 2.5 metres wide.
Racemes up to 20 cm long, flowering most of the year.
Michelia figo
Posted by Phytopath on Oct 29, 2010
Michelia figo is known in Australia as Port Wine Magnolia and in the Northern Hemisphere as Banana shrub.
Wow, such a small flower that really ‘packs a punch.’
I am lucky enough to have two of these wonderful shrubs and each spring I am alerted to the fact that they are in flower, not by looking, but by the beautiful aroma as I step outside in to the garden.
It is a wondrous experience that almost parallels the double choc fudge brownie with double cream and caramel sauce that I had for lunch today.
The plant is in the Magnolia family, correctly known as Magnoliaceae and has had a couple of botanical names.
Synonyms for Michelia figo are Magnolia fuscata (found in old text books) and Michelia fuscata.
The plant was named after a 17th century botanist called Pietro Antonio Micheli.
I am unsure why it was named after him or if the divine aroma of the flowers had any significance. If any readers or botanists out there know, please share.
The genus Michelia consists of around fifty tropical and sub-tropical, evergreen flowering trees and shrubs. They are closely related to Magnolia and are native to Asia.
So you can guess from their place of origin that they prefer a warm temperate to sub-tropical climate and a fairly sheltered position, although they are reasonably cold tolerant.
Most books tell you that they prefer plenty of sun but I have found the extremely harsh, hot dry summers here in Australia are just too hot for them. My plants receive morning sun and afternoon shade and are located in a north facing position for winter warmth (south facing if you are in the Northern Hemisphere).
Keep the plants well watered during spring and summer and try not to relocate them after their initial planting. They don’t particularly like being moved.
Michelia figo is a compact shrub, (especially if it is pruned lightly after flowering), that is slow growing, reaching 3 to 5 metres (10 to 16 feet) depending on climate, soil etc.
The best planting time is spring but if that is not possible, the next best time to plant is when it suits you, or leave it in a pot. They do well in containers.
The soil should be moderately rich and have good drainage. Fertilize well and cover the soil with a generous amount of leaf litter.
If you would like a plant but don’t yet have one, but your neighbour does, propagation is by seed or semi-hardwood cuttings during summer and autumn.
All Michelias bear their flowers in the leaf axils. They are small and appear in spring, are heavily scented and appear to be a different colour depending on where they are grown.
In the Northern Hemisphere the flowers are described as cream with purple streaks and an aroma like bananas, hence the common name.
In the Southern Hemisphere the outside flower petals are the colour of a rich port wine (hence the common name here) and apparently smell like port.
I believe we each interpret smells differently and to my nose, the flowers smell like bubble gum – sweet and fruity.
The essential oil of Michelia champaca, a close relative of the Port Wine Magnolia, is used in perfumery. Perhaps the essential oil of Michelia figo is not used because the wearer wouldn’t know whether to dab it on or lick if off.
Rose Pruning Basics
Posted by Phytopath on Jul 16, 2010
Flamingo
In the Southern Hemisphere we are approaching rose pruning time.
Although the flowers are beautiful, I must admit that I am not fond of the plant. You almost have to suit up in knight’s armour, as if going in to battle, just to get close and personal with them.
I do recall many years ago, a series of rose bushes that were bred to be thornless. At the time, I was working in a retail nursery and sales of the new rose were almost nonexistent. The flower shape was good and there was a range of about four colours to choose from.
Eventually I started asking customers why they were still buying traditional roses instead of the new thornless variety. The answer surprised me. “It is not a rose unless it has thorns” was the standard reply. Well bugger me, I thought. I bet they don’t prune their own rose bushes when planted on masse.
Anyway, If you have a few rose bushes and are new to rose pruning, here are some rose pruning basics.
Hybrid Tea, Floribunda and Bush Roses are the most commonly grown roses here in Australia. The standard procedure for pruning these plants is to first remove any dead wood. Then look for any branches that are crossing each other, which could lead to injury followed by infection. Once these have been located make a decision on which one should be removed.
Your decision may depend on the direction the branch is growing or the size of the branch, or the age of the branch.
The direction needs to be toward the outer part of the bush (i.e. growth pointing toward the outside of the bush) and not toward the centre. The size of the branch ideally should be larger than pencil thickness and young wood should be retained in preference to old wood.
Once the crossing branches have been dealt with, next you remove thin, spindly growth from all over the plant and then remove any growth which is growing into the centre of the plant.
If the plant has any obvious suckers (growth from below the graft) these should be removed but if the rose bush has water shoots (new, strong growth from above the graft) these need to be retained as they will form the future framework of the bush.
All of the above cuts should be made with a sharp tool (secateurs or loppers) and the cuts should be made flush with a stem. Do not leave stubs which could get die back.
The next and final step is to reduce the height of the rose bush. For a light prune you would remove about one third of the height (growth) and cut the stem to an outward facing bud. A light prune will give you more flowers but smaller in size (good for floribunda roses).
A hard prune, means removing about half or 50% of the height (growth) which will give you fewer flowers but larger blooms (good for hybrid tea roses).
Whatever you decide, it is highly unlikely that you will kill the rose bush. They are very forgiving and will still reward you with some beautiful flowers after they have scratched you to pieces first.
Climbing Roses are treated differently. They flower on old wood and these canes should not be cut back or shortened. Instead, one third of the old canes are removed completely at ground level each year after flowering. So if you have six canes growing from the base, you would remove the two oldest. That way, the plant is kept young and full of vigour. Flowering laterals can be shortened to 2 or 3 buds, again after flowering.
Banksia Rose
Banksia roses are simply thinned after flowering. Easy.
Weeping standard roses, just like the climbing roses, have all of the oldest canes removed from the base, up to 50% of the total number of stems can be removed.
Miniature roses are the easiest to prune. It is a bit like having a number one crew cut; you just shave the lot and leave stubble. This can be done by hand or with hedge shears. If the rose is a grafted one, make sure that the cuts are above the graft.
Winter in my garden
Posted by Phytopath on Jun 21, 2010
Butia capitata
I like the heat.
It’s not for everyone but I definitely have more energy when the temperature rises.
During the winter months (although reasonably mild where I live), I might as well be a grizzly bear. Hibernation is very attractive.
Because of my apparent unwillingness to garden outside during winter (unless the sun is shining), not a lot happens or is achieved in my garden, except for the occasional ‘weeding day’.
So today I went for a stroll around my garden (the sun was out) and took some photo’s to share with you.
Begonia
Bacopa
Schlumbergera
Melaleuca
Grevillea
Rose 'Flamingo'
Tetradenia syn. Iboza
Iochroma
Montanoa
Cockatoo's
Camellia
Posted by Phytopath on May 7, 2010
Paradise Pearl
I recently purchased a Camellia and at the time was undecided whether to buy a sasanqua or japonica. I eventually bought the sasanqua hybrid, because I liked the flowers, but it was also the best choice for my climate.
Camellia is from the Family Theaceae and there are currently over 300 named species.
The three most commonly grown camellias in Australia are C. japonica, C. sasanqua and C. reticulata. Of course there are also many hybrids available.
The greatest number of species occur in Southern China but they are also found growing in Japan and Indochina.
All species are evergreen shrubs or small trees and most have flowers in the white, pink and red range of colours, although there are some with flowers that are pale yellow to bronze in colour.
Most of the new releases have been deliberately hybridized and are no longer straight species of C. japonica, C. sasanqua or C. reticulata. Camellia japonica is parent to thousands of these cultivars and hybrids but few have any perfume.
Camellias grow best in well-drained, slightly acidic soil that is moist and enriched with organic matter. Good drainage is important because Camellias are susceptible to Phytopthora (root rot), but moist soil is also important for good growth.
The addition of organic matter can help with this because it has the capacity to hold water for later use by the plant.
Most Camellias are moderately frost hardy although some species are frost tender.
They enjoy a mild, humid climate and grow best in part shade. This of course will depend on local conditions. Camellia sasanqua is more sun tolerant than the others but morning sun is preferable to afternoon sun.
For longer lasting flowers and good looking foliage, semi shade is best.
Camellia sasanqua is a vigorous grower and the leaves are small and glossy. Because of the size of the leaves, this camellia is a good choice for formal hedging. The plant will respond well to pruning and the small leaves create a bushy appearance.
If you do not want to create a hedge then there is really no need for pruning but a light trim after flowering won’t hurt.
The sasanqua camellia produces an abundance of flower buds that open continually over a long period from early autumn until mid winter. It will flower in shade, semi-shade or full sun (not harsh) and most flowers have a fragrance. There are varieties with single or semi-double flowers and many seeds are produced.
Camellia japonica found growing in its natural habitat usually has red, five- petalled flowers that are quite small. The current garden variety of C. japonica has been through 300 years of careful selection. The Chinese favoured and selected plants with double flowers and the Japanese selected plants with single flowers.
Currently, cultivars are classified according to flower size and form. The smallest being miniatures with flowers under 6 cm (2½”), and then small, medium, medium-large, large and very large (sounds like an advertisement for clothing). The very large flowers are over 12 cm (5”).
The forms of flower are described as single, semi-double, anemone-form, informal double or peony-form, rose-form double and formal double. (It’s getting quite complicated and sounds to me like departments in a corporation). Would you like fries with that?
The japonica’s may need thinning if the foliage becomes very dense. Remove any branches that are crossing over and rubbing, and thin out the centre to allow more air to circulate and light to penetrate. The best time to prune is after flowering but you can also prune in early autumn. Wait until the flower buds have formed and then remove any stems that have no buds.
Camellia reticulata is more upright in growth habit than C. japonica and the leaves are large and leathery. They bloom from late winter to mid-spring and have some of the largest flowers of the camellia’s.
Below is a short list of the common camellia varieties and their respective growing zones.
Camellia japonica, zone 5 – 10
Camellia sasanqua, zone 9 – 11
Camellia reticulata, zone 7 – 10
Camellia oleifera, zone 7 – 10 (grown for the seed oil used in cooking and cosmetics)
Camellia sinensis, zone 9 – 11 (Tea)
What has been your experience growing Camellias?
By the way, this is my third attempt.
Flowers for Cutting
Posted by Phytopath on Apr 27, 2010
Flower arrangement
I spent twelve years in the Floriculture industry, growing and propagating protea, leucadendron, leucospermum and banksia. These plants were grown in the field under drip irrigation, on acidic sandy soil over clay. I was also involved with the growing of ‘soft’ flowers, meaning they were grown under cover. Some of the flowers grown were carnations, lisianthus and snapdragons, just to name a few.
It occurred to me that you may be interested in some ‘behind the scenes’ information of this industry.
Firstly, let me point out that this industry is not organic. There is an extremely heavy reliance on the use of chemicals. Unfortunately, because they are flowers, the first thing that most people do – is sniff the flowers. Please don’t do that unless you can guarantee that there is no chemical residue on the flowers or foliage.
The general public expect perfection in bunches of flowers, and florists also expect perfection with extra long stems. This is very hard to produce without the aid of chemicals. So chemicals are used to grow the plants, extend their stem length, keep bugs and diseases at bay and prolong the vase life after picking. It really is a cocktail.
As far as vase life is concerned, temperature plays a very important role.
For a plant to produce a flower, then nectar and ultimately seeds, it takes a great deal of energy. This energy is produced by respiration, through the consumption of sugars and starches that were produced during photosynthesis. It is very much like respiration in humans, that is, we derive our energy through the food we eat.
The high respiration rate produces heat which can be thought of as the rate of deterioration or death. Therefore, the faster the respiration rate, the sooner the flower will die. It seems logical then, that lowering the respiration rate will slow down the deterioration of the flower. This can be achieved by lowering the temperature.
Commercial flower growers and florists will keep the cut flowers under refrigeration. Of course there are always exceptions to the rule, and in this case, tropical flowers should not be kept at temperatures below 10°C.
There are three main temperature ‘groups’. The first is the tropical flowers which do not need to be cooled. The second group of plants require moderate refrigeration above 4°C but not higher than 6°C. Some plants in this group include: – gladioli, anemones, alstoemeria and acacia. The third group require full refrigeration at 1°C to 4°C. These include:- roses, carnations, chrysanthemums, gerbera, gypsophila and tulips.
Now obviously you want to display your flowers and not keep them in the refrigerator, so how can you prolong their vase life?
You could buy special flower preservatives to put in the vase with the flowers, or you could make your own. Here is a recipe straight from the horse’s mouth (so to speak).
1 litre water
2 teaspoons sugar
1 teaspoon vinegar OR a pinch of citric acid
¼ to 1 teaspoon household bleach
Mix all ingredients together and use in a vase with fresh cut flowers.
The idea behind this recipe is – the bleach will kill off any bad bugs or bacteria, the vinegar or citric acid will change the pH of the water to a more acid solution so the flower stems can then take up the sugar (food) more readily and it also unblocks any air bubble blockages that may have occurred when cutting the stems before placing them in water.
Another important factor in prolonging the vase life of cut flowers is the presence of ethylene.
Ethylene is a gas that cannot be smelled or seen. It reduces the vase life of cut flowers and accelerates their senescence. The major source of ethylene is car fumes, so be wary of buying flowers from shops who keep bunches of flowers in buckets on the footpath. Another source of ethylene is ripening fruit and dying flowers. If one flower in a bunch starts to die, the rest will soon follow and never keep a vase of flowers next to a bowl of fruit for the same reason.
I hope these tips have been helpful to you, and if you want sweet smelling flowers that are not loaded with chemicals, grow your own.
