librarian2003 (librarian2003) wrote in weagardening, @ 2012-02-06 23:15:00 |
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Week 2
We had some more interesting Plants of the Week, this week.
On Tuesday, Robert told us about Viburnum tinus and Judy told us about Lonicera x purpusii Winter Beauty.
On Friday, Margaret told us about the snowdrop, Galanthus, and Tracy told us about Sarcococca, Christmas Box.
All those images are here (after the images for Orchids, our main topic for this week):
Viburnum tinus, Lonicera x purpusii Winter Beauty, Galanthus and Sarcococca
The Sites of the Week handout is here - jut click on the links in the handout to go to the relevant websites:
GARDENING FOR PLEASURE
Spring Term 2011/12
Sites of the week : Week 2
1 Mail order orchids, but with comprehensive care guides.
Easy Orchids
http://www.easyorchids.co.uk
2 Lots of information from the specialists.
North of England Orchid Society
http://www.orchid.org.uk
3 Mail order and comprehensive guides from a specialist nursery founded in 1879
McBeans Orchids
http://www.mcbeansorchids.co.uk
4 For interesting bulbs
Avon Bulbs
http://www.avonbulbs.co.uk/
5 For articles, pictures, and all things to do with snowdrops
Judy’s Snowdrops
http://www.judyssnowdrops.co.uk/
Jo Hanslip
January 2012
Our main topic for this week is popular Orchids. Here are the handouts:
GARDENING FOR PLEASURE
Cymbidium Orchids
Cymbidiums are the oldest cultivated orchids, and there is evidence that they were grown in China 2500 years ago, in records from 500 BC at the time of Confucius.
The genus consists of about 50 species and, from these, thousands of hybrids have been bred. The wild types are found growing naturally in China, and Japan through the Himalayas, South East Asia to Australia. They may be terrestrial in habit or epiphytic or even lithophytic (growing on rocks), although those sold in the UK are generally terrestrial.
One of the easiest orchids to cultivate, given correct care it will flower year after year. Hybrids are classified into two groups: Intermediate, averaging 45 cm tall with 5 cm flowers, with a blooming season for the majority from October to April, and with flowers lasting six to eight weeks; and Standard, taller plants, up to about 1 metre, with larger flowers, most of which bloom from November to May, with flowers lasting for eight to twelve weeks.
Cymbidiums grow by producing pseudobulbs - swollen, above-ground structures from which the leaves grow. These are generally cylindrical or conical in shape, and help the plant to store water and nutrients. Cymbidiums are vigorous orchids and when a pot is filled with these bulbs, you can split them apart to make more plants.
Cymbidiums are terrestrial orchids which do not like a heavy compost. A well aerated, free draining compost is best. For orchids grown in a peat and perlite mix, allow the bulk of the compost to become dry before giving a thorough watering. Be careful not to waterlog the compost by watering too frequently. But if it's in rockwool, never allow the compost to dry out completely or it will harden. It's extremely difficult to make the rockwool hold sufficient moisture again.
Never stand the plant in excess water but make sure that it's allowed to drain away. Be especially careful if the pot is placed inside another container where the water may get trapped.
They require good ventilation or air movement and lots of light, but not strong sunlight.
Cymbidiums do best where night-time temperature does not drop below 50F or 10C.
Plants can be kept outdoors from mid- to late summer (June to September). Gradually acclimatise the plants to outdoor conditions in order to prevent leaf scorch from cold temperatures or direct sun. When putting it out, take care to 'harden' the plant to the outside conditions, particularly the high light. Place it in a semi-shaded position, then gradually increase light levels. When returning your plant indoors, acclimatise it gradually. A sudden burst of heat could result in bud drop.
Flower spike initiation takes place in mid- to late summer, when plants require good light and a distinct difference between warmer day and cooler night temperatures. Placing the plants outside helps to provide such conditions. To prevent bud-drop, keep the temperature below 15°C (59°F) during flower spike development. Wait until the flowers have opened before moving the plant into a warmer environment for display purposes.
Support developing flower spikes with a bamboo cane. Once the blooms have faded, cut down the flowered stem to the base.
Use a well-balanced orchid fertiliser (ratio 20-20-20) at the recommended strength throughout spring and summer. Flush the compost through with plain water at every fourth watering. Reduce the fertilizer strength to half the recommended dose through autumn and winter. If using a general fertilizer, use it at no more than half strength. To help flower spike initiation, do not fertilize during July.
It is generally true that larger plants produce more flowers proportionately than smaller ones but at some point it is necessary to divide the plant into pieces and repot, usually for one or more of the following reasons: (1) the pot and plant are too big to be handled or housed properly; (2) there are too many "back bulbs" taking up too much space; and/or (3) the potting mix has been exhausted and the plant may be living on its old, decaying roots (three years is often considered an average limit).
Repot cymbidiums immediately flowering has finished, from February until May. Cut the plant at the underground rhizome to give divisions, each of which should have not less than three or four bulbs. Leave one of the 'back bulbs' or 'pseudo bulbs' on each division; these are the bulbs that have lost all leaves. Back bulbs act as a nutrient supply. If you are changing from growing in rockwool it is important to remove all the old material before replanting in a new compost mix.
Removing the plant from its present pot requires a knock or tap or two to dislodge the root mass. If the pot is wedged in place by fleshy roots, you may have to cut if off carefully with a knife. Most hobbyists and commercial growers remove the lower 1/3 to ½ of the root ball using a sterile knife. The plant mass usually can be broken apart at natural splitting points, but wherever the rhizome is severed, this should produce an additional growing point. Healthy roots should be shortened to 3-4 inches. Dead or withered roots should be removed. Potting mix should be moist at the time of use. Also, since there are always many newly-cut root tips, it is a good practice to allow the divisions to air dry for a period of time to allow the root tissue to heal over (not in the sun).
Choose a container that best fits each division. The plants always grow better if they are contained, so never overpot. Only repot into plant pots where there is just enough room for the following year's growth. Press the mix firmly around the root mass up to and around the first 1/3 of the green bulbs. Some growers do not water the potted divisions immediately allowing healing to take place at the root level; others water immediately until drainage water comes out clear from the container. In either case, fresh potted divisions are placed in a cool, shady protected area for about two weeks with occasional misting. They are then returned to a regular growing area and normal light and watering. Plants should have rooted within about ten weeks.
Cymbidium can suffer the same problems as other orchids, including mealybug, red spider mite, aphids, and slug and snail damage (if kept outdoors).
Jo Hanslip
January 2010
GARDENING FOR PLEASURE
Dendrobium nobile
There are over a thousand known species of Dendrobium (pronounced den-dro-bee-um), and still more are being discovered in the highlands of New Guinea. This makes them the second largest orchid genus in the world after Bulbophyllum.
The shape and form of their stems and leaves vary tremendously, but the pattern of flowers is fairly constant ranging in size from very small to huge. Typically the bases of the sepals are fused to the foot of the column and the lip base forming a mentum or 'chin' which often houses nectar.
Nobile Dendrobiums are some of the easiest to grow but can be a little difficult to bloom regularly. Their flowers are showy, and a single plant can have hundreds, with colours ranging from white through pink to purple, and the lip is often beautifully marked in contrasting colours. They make magnificent specimen plants. Others are yellow and brown, while the recently introduced Yamamoto hybrids have all the colours of the rainbow. The Himalayan climate is not unlike a warmer Switzerland, with bright, cold but dry winters.
November-February: daytime temperatures can drop to 40° - 45° when you should not water or feed but give plenty of light and air movement. This is one of the key elements - NO WATERING from mid November until February. If your atmosphere is very dry then you can mist your plants once a month to avoid over drying them or give them a good SINGLE soak every 8 weeks.
March-May or June: warmer and moister conditions. Buds develop and new growths appear. Water sparingly until the new shoots have grown good roots.
From June-November corresponds to the monsoon period, warm and very wet. Give a low strength, high nitrogen feed in April and May, then feed weekly during maximum growth. Change to high potash for the last month.
Note: If you do not dry and cool the plants during winter, you won't get flowers. Himalayan Dendrobiums from lower altitudes need a less harsh winter but still dry.
Dendrobiums like good light at all times but they should not be kept in full sun or they may scorch. Keep them in the brightest position during the winter months to help ripen the current year’s stems, called canes.
Repotting and dividing should be undertaken in the spring either immediately after flowering or just as new growth starts. These plants need the roots confining and should always be under potted rather than over potted as this will help prevent over watering. These plants produce an enormous amount of aerial roots and so are ideal candidates for growing in many ways other than pots. They can be mounted on cork bark or even grown over a tree stump, they will become top heavy though but thanks to the abundance of anchoring roots should be stable by the following season after mounting.
Jo Hanslip
January 2012
GARDENING FOR PLEASURE
Phalaenopsis
One of the most popular orchids grown as houseplants is the Moth Orchid or Phalaenopsis. They make good indoor plants because they can tolerate the drier heat of central heating as well as being almost perpetually flowering. They produce arching spikes of ten or more flowers as often as three times a year. Many hundreds of hybrids have been bred, and the trade in Phalaenopsis is a huge pot-plant market because of the ease of cultivation.
There are just under 50 wild species, found from India eastwards to the Philippines and into Northern Australia. The name Phalaenopsis is from the Greek and means moth-like. The plants are shade-loving and grow on branches or on rocks where the air is warm and moist.
They do not have bulbs like other orchids but instead grow with fleshy leaves, new ones forming from the central crown. New leaves appear slowly and regularly over each other and are generally a deep green but occasionally can be attractively mottled. The flowers appear on a spike from the stem between the leaves and, depending on the type, there may be anything from a single flower to over a hundred. They also produce a lot of aerial roots that come over the side of the pot as well as into the bark compost.
They like a minimum temperature of 20°C (68°F) although adult plants grow happily at 15"C (60"F) and actually flower better after a few weeks at this night temperature in autumn. If a plant is large and healthy but does not produce flowers in a reasonable time, then reduce the temperature by 5°C (8°F) for four weeks, and a flower spike will usually develop.
They will benefit from being over (but not in) a tray of pebbles that should be kept wet to boost the atmospheric humidity. Mist the plant lightly in summer. Keep shaded from bright, direct summer sun as this can scorch the leaves. Ensure good light levels in winter, as these are essential to encourage flowering.
As they do not have storage pseudobulbs, keep the free-draining bark compost moist all the year round. Avoid using cold water and don't allow water to remain in the crown of the plants for more than a couple of hours as it can induce rotting. When watering the plant, remove it from any cover pot or saucer, pour water through the pot and then let it drain before placing it back in a decorative planter. Never let the pot stand in water. Allow the compost to dry out slightly and the pot to become lighter before watering again. Add a little orchid fertiliser to the water once every 2 or 3 waterings (approx. every 10-14 days) all year round.
The plant will continue to make more buds from the end of the stem, the flowers gradually opening in succession. Along the length of the main stem there are many eyes or nodes. When flowering has finished, or ideally has one or two flowers left, you can trim off the spike to around 1 inch above the first node on the main spike stem, which will be somewhere below where the first flower appeared, and is a little bump covered by a small leaflet. The plant may re spike and flower early from there. If the spike has died fully, and gone brown, trim off the flower spikes to within 1 inch of where they appeared out of the side of the plant. It should re bloom on new spikes next year.
Occasionally a flower bud will develop into a small plant with roots which can be cut off and potted up. These propagations may flower within a couple of years.
Clear pots are ideal for these plants, the roots seem to benefit from the light, and you can also see any root problem developing before it’s too late. Use a coarse bark mixture with added charcoal, perlite (and sphagnum moss, or horticultural sponge, if in quick drying conditions). The roots often grow outside the pot, but this is quite natural and indicates that you are doing things right.
Re-pot your Phalaenopsis only when it is climbing out of its pot. Re-pot between March and June using coarse free draining specialist orchid compost. Do not re-pot into too large a pot and choose a pot just large enough to contain the roots. Do not try to bury the fleshy white aerial roots that extend above the pot, as they are prone to rotting. Cut the old flower stem right back to the base and if still in flower, the blooms can be placed in water.
Remove the plant from its pot and shake off the majority of the old bark compost.
Using clean, sharp secateurs or scissors, trim back the roots to a length of about 10cm minimum. Healthy roots should be white or green and plump. Over-watered roots are brown and shrivelled. Take this opportunity to remove any dead leaves and completely dead roots.
Position the plant in a clean pot, slightly bigger if necessary, and hold in place, centrally with one hand, whilst filling up with fresh bark compost with the other. They grow well in clear pots but these are not essential. Choose any container that has plenty of drainage holes.
Making sure the bark is pressed down firmly to anchor the plant, top it up to just below the rim of the pot. Make a note of the potting date on the label. Use the clear pot to your advantage, keep an eye on the roots and you will see if they are keeping healthy.
Water about once every 1-2 weeks and spray the surface of the compost to encourage the new roots to grow. Soon it will make a new leaf and the next flower spike will shortly follow.
Phalaenopsis suffer from the same problems as other orchids, including mealybug, slugs and snails.
Jo Hanslip
February 2010
Orchid images are here:
Orchids
Any questions? Comments?
Next week, we're looking at the Garden in February, so don't forget to have a look at your Garden Diary.
Jo