Tag Archive | GardenEzi

Cold comfort for tropical foliage

Tropical foliage plants can catch cold!  Truly!  Though most of the plants that fall into this category originate in the true tropics where days are hot and humid and night temperatures don’t drop very low at any time of year, these plants are nowadays grown in a wider temperature range from the sub-tropics to sheltered warm-temperate gardens where there is a decided “down” season when temperatures drop.  In the southern hemisphere that may coincide with the “winter” dry season where special care is needed.

What’s more, though plants such as bromeliads and many orchids come from the tropic latitudes, they occur naturally at high altitudes where lower temperatures occur and constant cloud cover prevents sun warmth getting through.  So they can tolerate – indeed may well require – quite low temperatures at times.

So unless you lived on a tropic beach with very little climate variation all year round, read on!

The two conditions which can send tropical foliage plants – or tropical flowering plants for that matter – into oblivion are cold and drought.  As most warm climates have a season in which little or no rain falls (for example tropical northern Australia, parts of Central and northern South America, India and Africa) and where temperatures are low at night, some tropical foliage plants have developed strategies to deal with this – they go to ground.  Caladiums and tropical gingers both do this.  In fact many popular tropical foliage “indoor” plants have a dormancy period when neither, new stems, leaves or flowers are produced.  Spathiphyllums, anthuriums and calatheas do this – and so, among the flowering plants, do orchids.  This is vital to their life-cycle.

Anthuriums are very susceptible to cold and have a cool-season dormancy period

This “down” period renders the plant very vulnerable, especially where there is a marked change between summer and winter, high rainfall and low rainfall.  The two important considerations here are COLD and MOISTURE.

COLD

Isolated plants are lonely plants and, just as humans can survive cold by huddling together and using their combined body temperatures to create and share warmth, so can plants.  This is especially true of all those plants that we categorise as “tropical foliage” – the spathiphyllums, pileas, aspidistras, calatheas, marantas and others (for a full list go to  www.wix.com/jrlakemedia/ezibooks )- which come from crowded jungles.  If you are growing these plants in pots you can bring them indoors for the cool season.  If you are growing them in the garden then they must be massed together so temperature and moisture levels can be maintained at a higher level than the surrounding air.  This massed planting also helps keep the soil warm and moist.

Shade from palms and other trees will protect your tropical foliage plants from frost danger and wind exposure.  However morning sun is beneficial in cooler weather so create (or recreate)your planting scheme so that it faces the sunrise.  In sub-tropical and warm-temperate gardens use palms and briefly deciduous trees such as coral trees (erythrinas) and tabebuias as the overhead cover.  These will allow sufficient sunlight to filter through to the plants below in the cool season. DON’T plant your tropical foliage garden where it has no shelter from chill cool-season winds and exposure.

Cold, wet ground is the main killer of tropical foliage plants.  If these conditions are prolonged they will just curl up their leaves and die.  Root-rot fungal diseases thrive when soil is wet and cold and poorly drained. An early warning sign is moss growing on top of the hard-packed ground.  I have a corner of my garden that has heavy, poorly-drained soil that gets very soggy in winter when the sun only gets to it for an hour or so a day.  This combination is fatal to plants like cordylines and crotons and I’ve lost a few.  I now mulch, mulch, mulch to improve the soil and have dug a drain to channel excess water away from the planted area.

The other tropical plant assassins are, of course, frost or hail.  I get both where I live.  If you have sufficient overhead cover light frost shouldn’t be a problem; if on a frosty morning you notice some plants are affected hose them down quickly – though you probably won’t be able to save them. If you live where regular, severe frosts occur then you shouldn’t be growing these plants anyway! Hail shreds the leaves of fleshy foliage plants and there’s not much you can do about it except trim them back so new growth is encouraged – this being a plant’s natural response to disaster.  More dangerous is hail bruising of plant stems which can cause deep cell damage and leave the plant susceptible to fungal attack.  The same result will happen if the ice remains for any time piled up against the stem.  So after a hail storm push back the hailstones as fast as possible and water down the leaves and stems.  As with frost, an overhead canopy will protect plants below from the worst of a hailstorm.  Of course, hail is usually (but not always) a spring, summer or even autumn problem but I thought I’d include it here because it comes under the “cold” category as far as tender plants are concerned.

If you live in a sub-tropical, warm-temperate or fairly arid area some plants can give you a tropical appearance while still being able to take greater extremes of cold and low rainfall; they include:

Acalypha

Coleus

Cordyline

Croton

Ctenanthe

Dracaena

Philodendron (several types)

Poinsettia

Scheflera

Strobilanthes

MOISTURE

Don’t, don’t, DON’T over-water tropical foliage plants in the cool-season because few of them make any growth at this time and they can’t use the water – worse,  too much of it will cause root rot.  Yes, I know these are plants from high rainfall areas that thrive on heat and moisture and our instincts tell us to keep them soaked when the rain isn’t falling.  But nature gives them heavy monsoonal drenching alternating with dry periods, or in some equatorial areas a nightly drenching and a daily dry-out.  But they are not programmed to be waterlogged all the time.  So the only time you need to provide them with water is in prolonged dry periods, especially if it’s windy.  In such cases a light, misting spray twice a week is quite enough.

Caladiums need a lot of water in summer but die back and go underground in the cool season

Finally, DON’T fertilize your tropical foliage plants in winter (and that goes for those grown indoors as “house” plants, too!).  They won’t be able to make use of the extra nutrients anyway.  Save your efforts until late spring or just before the monsoon, depending on where you live,then give them a good dressing of blood-and-bone or chicken-poo pellets or well-made compost.

So that’s all there is to it.  When it comes to getting your tropical foliage plants through the cool-season dormancy period, keep ‘em warm and keep ‘em dry.  Bit like babies, really!

(And if you want to know more about growing these plants of creating a Tropical Foliage Garden you might like to look at my book on the subject, only $4.95 as an e-reader or PC download from Amazon, see the GardenEzi  website at www.wix.com/jrlakemedia/ezibooks )

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Growing dendrobium orchids the GardenEzi way

King orchid growing on a rock

(This article is for those who live in climates where they can grow Dendrobium orchids out of doors.  It’s not for collectors and competition growers whose plants, especially if grown in cooler climates indoors, need a much higher degree of care).

Dendrobium orchids are very independent plants and they don’t like a lot of fuss.  Gardeners who have problems growing them remind me of parents who treat their children like hothouse plants – won’t let them do this, won’t let them do that in case they come to harm.  Rearing children in this unnatural way turns them into adults who lack strength of character and the ability to fend for themselves.  It’s just the same with dendrobiums – give them the right environment and the basics of a good life and they’ll grow up big and strong and tough and resilient, able to survive all the world can throw at them. When they are in flower you think that anything so exquisitely delicate MUST need hothouse conditions – yet in the wild they grow on trees and rocks, exposed to the elements, surviving drenching rain and drought.

Cooktown orchid (Dendrobium phalaeonopsis)

Ever since I founded the GardenEzi easy gardening Five Step Program (see www.wix.com/jrlakemedia/ezibooks ) I have used the same method for writing most plant articles as I do for my books – breaking it all down into the Five Ps of gardening: Planning, Preparation, Planting, Practice and Protection.  So here goes:

PLANNING – Much depends on where you wish to grow your orchid. You may wish to imitate nature and place it on a tree or rock in your garden.  More likely, however, you will want to provide it with an artificial growing medium such as a piece of bark fastened to a hard surface, or a cork board, a pot, or a basket. Dendrobiums do best in a position where they have morning sun and light overhead shade, with protection from direct midday and afternoon sun, as well as hot winds, cold winds and (if grown on or near the ground) frost.  The Australian “king” or “rock” orchid Dendrobium speciosum will handle temperatures down to zero or even a bit below for short periods, as will the pink rock orchid (Dendrobium kingianum); the Cooktown orchid (Dendrobium phalaeonopsis) will tolerate temperatures down to 50 degrees F (10 degrees C) and so will the popular Dendrobium nobile hybrids.  Some of the Asian and Pacific species require higher temperatures and no frost but all dendrobiums cultivated in gardens require night temperatures of no less than 60 degrees F (15.5 degrees C) during their dormancy period in order to flower later.  When planning for containers, it’s the size of the maturing stems and leaves that’s important – the root system grows very slowly while you can expect at least one new step a year.  Choose a size roughly twice that of the plant and pot (or basket!) on as required.

PREPARATION – If you are growing your dendrobium in a pot or basket (the latter is better) make sure the container is filled with plenty of coarse, fibrous material.  You can buy a commercial orchid mix or make your own with coconut fiber or peat moss.  If using a pot make sure it is shallow, wide at the base and has at least THREE good-sized drainage holes; put small rocks or pebbles or bits of broken-up terracotta pot in the bottom, to ensure perfect drainage.  You can’t pot these orchids using an ordinary potting mix and expect them to do well – they are epiphytes that must develop an extensive mat of roots to survive and grow.  They can do this on a wall or rough wooden fence, provided you place them on a slab of bark or cork to start with; in a pot or basket the roots will need plenty of room to spread.  I prefer a cane or wooden basket, placed where the roots can grow outside the container on to some other surface when they are long enough, or be easily trimmed back if necessary. Pack the bottom of the basket with sphagnum or peat moss (I once used an old coir doormat, chopped into pieces, with great success!), then add some coarse orchid mix.  I usually put in a few twigs and leaf mold from the garden to hold this in place and provide plenty of “open work”; a few small rocks are good too, or a handful of coarse gravel.  The idea is to give the roots protection and some initial nutrition while allowing free drainage.

PLANTING – (Or placing!).  If you are going to grow your orchid on a tree or rock, tie it firmly in place with any binding material that will rot away as the orchid roots spread and find their own anchorage.  NOT plastic, or wire!  If you’ve bought it already fastened to a piece of bark or similar, you need only to bind this to the growing place.  If it’s in a pot you’ll need to remove it carefully so that the roots aren’t damaged and then bind it in place.  The same goes for a division from somebody else’s plant – in both these cases pack sphagnum or peat moss, or soft bark, or burlap (hessian) around the root system and tie the whole lot in place.  If you are growing in a pot or basket take the same care in handling the roots and see they are securely in place with the growing medium packed loosely but thoroughly around them.  Use the same careful root-handling procedure when potting on, once the plant becomes too large for its container – where necessary cut the roots with a sharp, clean knife.  Mature plants can also be divided in this way, increasing your collection.

PRACTICE – In warm-temperate, sub-tropical and tropical climates the dendrobiums readily available to gardeners don’t need to be moved under cover in winter.  They all experience a cold-season dormancy period when they produce no new shoots and at this time they require very little water.  I usually give mine a sprinkle or spray with a fine mister once a week if the weather is very dry, or if I notice any sign of dessication in leaves or stems.  In areas with winter rainfall, overhead protection will prevent the plants becoming too wet for prolonged periods. In summer, when new shoots appear, watering should be regular and plentiful except when it’s raining.  Though feeding is not strictly necessary, if you want more and better flowers then apply a half-strength monthly dose of liquid fertilizer.  I use a standard balanced mixture in summer to encourage leaf and stem development, switching in autumn to one which is higher in phosphorus and lower in nitrogen, to encourage flower development.  This rewards me with superb spring blossoms.  Other growers have different methods but there is general agreement on regular light summer and autumn feeding, and no fertilizer at all in the cool season of dormancy.  No pruning is necessary but it’s a good idea to remove any withered leaves or canes as these are not only unsightly but may indicate a fungal disease which can spread to the whole plant.

PROTECTION – I never give my dendrobiums any protection at all against insects.  Nor have I ever had any problem with fungal diseases. As these orchids grow outside, rather than in a bush or greenhouse, Mother Nature seems to take care of pests.  However, like all plants they CAN be susceptible to attacks from insects such as aphids, thrips, scale and two-spotted (red spider) mite. All these can be dealt with by washing down with ordinary dishwashing detergent, though repeated infestations might need a chemical treatment as recommended by your nursery retailer.  Rusts can be a problem, showing as reddish-brown marks on the leaves and stems. These tend to occur in long periods of continuously wet weather.  You can buy a treatment from your nursery retailer. Other fungal diseases are usually too advanced by the time you notice the effects and it’s mostly a waste of time trying to treat a plant that starts to blacken and rot.  The best regime is to make sure your orchids are well-drained, have plenty of air around them, won’t suffer from sunburn (which will scorch the leaves and leave them shriveled and susceptible to fungal attack), and are not exposed to frost, hail or wind.

There is a lot more I could say about growing dendrobiums – especially about propagation and the many different species and varieties available today.  But this is enough to get you started – if you want to know more, contact me on my GardenEzi website, or via this blog, and I’ll answer any questions.

In praise of old azaleas

People often ask me, what are the best azaleas to grow?

I always tell them – go for the oldies! Because where azaleas are concerned, the oldies really ARE the goodies, if what you want are big, strong, floriferous and reliable plants to fill a space or make a show.

In this regard, the old indica species azaleas such as “Alphonse Anderson”, “Alba Magna” and “Exquisite” still out-perform every other type.
They go on blooming year after year, decade after decade, and all they require is a bit of water in very dry weather, regular mulching with acidic stuff such as leaf mould or straw, and a good cut-back after flowering.

Of course, there are lots of lovely azalea varieties available today in all sorts of colors. And when it comes to selecting varieties of indica, mollis or kurume much depends on your climate – as a general rule indicas are the best for warmer climates while the deciduous mollis and compact kurumes thrive only in cold or upland climates. Azaleas have been so hybridized and genetically mucked about that the range available in a garden centre can be bewildering, unless you have a definite color scheme in mind.

The faithful old tall-growing indicas already mentioned here don’t produce autumn flowers, as do so many of the newer hybrid varieties . But though they only flower in spring (with occasional – but rare – spot flowering throughout the year) they do produce a good show for several weeks. And they are much less prone to petal blight and just plain dropping down dead than the newbies, where breeding seems to be aimed more at bringing out yet another flashy-flowered brief sensation rather than a vigorous plant.