From Jon Lamb Communications
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December 4, 2020

Red spider mite creating havoc

The combination of red spider mite, dry soil and last week’s very hot weather has had a devastating effect in many gardens, particularly tomato plants and rose bushes.
If the leaves on your tomatoes, roses (and other ornamentals) have lost their natural fresh green lustre – maybe turning yellow – and are starting to drop, it’s likely your plants are under attack from red spider mite.
Spider mites are sapsuckers.
They are minute and during hot, dry weather their populations can explode.

Your best control options

The most effective control chemical for red spider mites on ornamentals and most vegetables – but not cucumbers and zucchini – is wettable sulphur.
The combination of potassium soaps (Natrasoap) and horticultural oil (eco-oil, Pest oil) is also effective (on all plants), particularly if used before numbers get out of hand.
The use of Mavrik, a synthetic pyrethroid is worth trying – but in some gardens the mites have developed resistance to this chemical.

Repeat spraying essential: To achieve effective control when mite populations are high, you will need to respray two or three times at 5 to 7 day intervals.
Sulphur and oil sprays should not be used when temperatures are over 32 C.

The effects of high temperatures on plant growth

Last week’s sudden burst of heat raises the question – what happens to plants, and in particular their roots, when temperatures start to spike?
While garden plants vary considerably in their tolerance to heat, during a heat spike the soil can become so hot the plant’s roots are unable to function properly.
The effects of rising soil temperatures and the importance of shade were highlighted during ABC TalkBack Gardening last Saturday.

A summary of this discussion and a guide to critical soil temperatures here »

Many gardens invaded by white fly

A cloud of white fly suspended over your favourite vegetables or ornamentals can look rather menacing.
However, during their adult or flying state, white fly do not cause much damage. 
It is the juvenile or young stage, (identified as small white or opaque scale on the back of leaves) that causes the damage.
Small numbers can be ignored as it’s likely they will be contained by a parasitic wasp.
However, if the leaves of plants are being damaged, chemical control is warranted.
Spray plants thoroughly with a horticultural oil or horticultural soap (Natrasoap).
Both are non-toxic.  Also effective (but not selective) are Mavrik or pyrethrum sprays.
Two sprays, two weeks apart may be needed.
Feature plantsof the week

Polka dot plants eye-catching and easy to grow

Hypoestes, also known as the polka dot plant, is an eye-catching little plant with brightly spotted leaves that stand out against most other foliage.
And the good news  – Hypoestes are not especially difficult to grow.
For top results these colourful plants are best planted in spring and early summer. They have a moderate growth rate and remain relatively small as they mature, especially when grown indoors.
To produce good leaf colour Easy Colour recommends growing hypoestes in bright, filtered light rather than full sun. However, the leaves also fade out in low light.
Warm temperatures and humidity are also important for success and expect to water the plants regularly unless you have sufficient rainfall.
Because the plants tend to become leggy as they mature, Easy Colour suggests pinching out the top two leaves on each stem on a weekly basis. This will promote a bushier shape and produce healthier more vigorous plants.
 Look for Hypoestes in the distinctive Easy Colour purple 4 cell packs.
Easy Colour
Hypoestes are in stock at Heyne's Garden Centre, Norwood , Semaphore Pets & Gardens and Barrow & Bench, Malvern and should be available at other good gardening centres.

Canna Emerald Sunset is a show off

Emerald Sunset with its large, ruffled, orange flowers and dark emerald green foliage belongs to a relatively new series of colourful cannas known as Show Offs.
These have been selected for their striking foliage (which varies with variety) and the vibrant colours of their flowers. They certainly blend well in a modern garden.
Show Off cannas produce their best display through the warmer months, with each flower spike producing new blooms over many weeks.
Plants established in garden beds should be mulched and the soil kept moist through the growing season.
However, they can also be used as potted plants, so long as they are kept continually moist while they are producing blooms.
Once each flower stalk has finished flowering it should be cut back hard to promote further blooms through summer and autumn.

Proven WinnersCanna Emerald Sunset are in stock at Heynes Garden Centre, Norwood, Semaphore Pets & Gardens and Barrow & Bench, Malvern and should be available at other good gardening centres.

Budding  time

Late November and early December is a good time to bud rose bushes, stone and pome fruit trees and citrus.

Soil wetters at work              

If can be very frustrating when you water plants in hanging baskets and containers during  hot weather and the water runs down the sides of the container – rather than soaking into the root ball.
When this happens treat yourself or at least the plants to an application of soil wetting liquid or granules. 
Both work well. 
Soil wetters have an amazing ability to make the water soak into the root zone rather than run over it.

Organic or compound fertilisers?

“Best results will be achieved by applying an organic fertiliser blended specifically for vegetables.”
This was a recommendation suggested in a vegetable item in last week’s newsletter.
But “what’s the difference between using an organic or compound fertiliser” is the issue raised by Roseworthy-based cropping and horticultural agronomist, Chris Butler.
According to Chris it's speed of availability.

He writes:
“If a lemon tree is well mulched with good organic matter levels in the top 10 cm of soil and it needs some nutrients, the compound fertiliser will work better, as some nutrients will be available immediately. The balance will be absorbed into the soil and organic matter and released slowly.
The organic fertiliser will supply the same amount of nutrients, but the plant will have to wait while it becomes available.”

Chris concludes there is a place for both, but the value of compound fertilisers should not be overlooked.

Firestar – an international award-winning rose

Firestar has fascinating flowers made up of unusually frilly petals.
These produces a kaleidoscope of colours starting from Scarlet buds opening to mandarin orange blooms, softening to raspberry pink with age.
The blooms are medium to large, produced in clusters of 3 to 5 per stem and are lightly fragrant. These appear from spring through to winter
Very good disease resistance, exceptional performance, height 1 m.
Firestar is the official Rose of the CFS foundation, with Knight's Roses providing funds to the foundation from sales.

Per fyoom Perfume for unbeatable fragrance

This award-winning rose will wow you with its gloriously fragrant blooms.
The scents are of Victorian rose, myrrh and apple blossom, while the blooms are shaped in beautiful fairy floss pink.
Healthy medium green glossy foliage completes the picture.
A rose with a five out of five star rating. Exceptional performance in most conditions.

More information »
Per fyoom Perfume
Potted Roses available now.  Pre-order your bareroot roses for 2021.
Phone 08 852311 or email
Knight's Roses
Knights' Roses, one of the largest rose growers and suppliers in Australia, offer a comprehensive collection of rose bushes to both wholesalers and the public. 44 Jack Cooper Drive, Gawler, SA. Phone (08) 8523 1311.

Reducing garden water costs

There is considerable scope for most householders to reduce the amount of water they use in the garden.
An efficient irrigation system can reduce your water use by 50 to 70 percent.
Low-throw, rotating-nozzle sprinklers deliver water slowly (less run off ) in thin, semi-horizontal streams rather than as  a fine, semi-vertical spray (much lower evaporation losses).
Drip irrigation and micro streams (shrublers) allow you to water the root zone of individual plants without wasting water on the bare spaces in between.
Automated (set and forget) timer systems will also help you limit your water use.

Do it yourself

These systems are very easy to install, relatively inexpensive and can certainly take the hard work out of watering, particularly plants in raised garden beds and containers.
During January Good Gardening will provide more details on these water saving systems.

Water placement is critical

As a general guide, most vegetables, flowers and small shrubs have at least 50 percent of their moisture-absorbing roots in the top 10 cm of soil.
This is the critical area that you need to keep both moist and cool during hot weather.
On the other hand, if you water lightly during hot weather a big percentage of the moisture you apply will be lost through evaporation.

Better bucketing

The effectiveness of bucket and hand watering can be increased dramatically simply by digging a shallow trench or basin around the plant’s drip ring. 
This will allow you to place water at the right location and in the right position.
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Early summer no barrier to planting seedlings

Don’t stop transplanting vegetable, herb and flower seedlings simply because it’s now summer.
Well established seedlings planted into garden beds or containers over the next few weeks will grow rapidly; with lettuce and other leafy salad lines ready to harvest in 4-6 weeks.
Reduce transplant shock: What happens in the first 12 hours after transplanting seedlings is critical.
Transplanting is best carried out late in the afternoon as this reduces the number of hours the plants will be exposed to the sun on the first day. 
Also, have some temporary shading material standing by in case of the inevitable heatwave. 
During summer when hot weather is forecast, try to coincide planting out with the beginning of a cool change that is likely to last for three or four days. 
This gives the seedlings time to establish an active root system - before being stressed by the heat.
Lawn Care – Stefan Palm, Paul Munns

Solving the problem of spongy lawns   

What to do when you’re attractive couch or kikuyu lawn becomes spongy?
To do nothing is not a good option, particularly when the grass starts to lose its soft green colour or even worse, the mower blades create unsightly brown scars across the stand.
The solution, according to turf consultant Stefan Palm, is to scarify the lawn, a task that Stefan believes you can carry out yourself using your own lawnmower.
In this week’s lawn blog Stefan explains why couch and kikuyu lawns often becomes spongy and also provides an easy to follow guide to the task of scarification.

More information »
Paul Munns Instant Lawn

Meet the basil family

Early summer is an excellent time to begin growing basil.
This versatile herb is widely used in pasta, tomato dishes, salads and pesto.
Basil flavours are very intense and it’s worth noting, there are many different types and flavours worth trying.

Sweet basil with its very pleasant clove-like scent and flavour is the most widely grown.
Other popular forms include:
  • Basil bush (50 cm high).Mild cinnamon, cloves and aniseed flavours.
  • Green ruffles (60 cm).Mild, sweet basil with aniseed and mint.
  • Lime (65 cm). Sweet basil with lime.
  • Native (35 cm).Spicy aniseed.
  • Purple ruffles (70 cm).Sweet basil with cinnamon.
  • Thai (75 cm).Spicy, aniseed and hint of mint.
Also worth growing:  Parsley, chives, oregano, rocket.

Kitchen herbs – getting started

Most kitchen herbs are sun lovers but during summer they grow best under 50 percent shade.
All you have to do is re-pot your selections into slightly larger containers.
As a general rule, the smaller the container the more often you have to water the plants.
In most cases it's best to re-pot individual plants into separate containers.  Something 25-30cm in diameter is ideal.
Alternatively, herbs of similar size such as chives, parsley, rocket and many of the non hearting lettuce can be placed together in the one large (30 to 40 cm) container. 

Increasing the size of table grapes

The size of table grapes can be improved considerably by bunch thinning.
This involves removing the bottom 20 pc (the tale) from large, long bunches and on some varieties the shoulder bunch as well.
This task should be carried out just before or soon after flowering.

Apricots fresh from the garden

The size and quality of apricots that will ripen soon after Christmas can be improved significantly by increasing the amount of water the trees receive over the next few weeks.
A medium size tree carrying an average sized crop should be receiving 200 litres of water per week. 
This amount should be increased to 400 to 500 L per week towards harvest. 
However, withdraw all water once the fruits begin to ripen.

Trim topiary and hedges lightly

Topiary and hedging plants are currently making vigorous growth.
Resist the temptation to grab your pruning equipment and administer a “short back and sides”.
Hard pruning in the middle of summer is likely to result in exposed branches and leaves becoming burnt by the sun.
With topiary and hedging plants the aim during summer should be to only remove the tip growth, along with any individual branches that extend well beyond their normal canopy.
Tip pruning will encourage these plants to cover their canopies with attractive new leaves.
At the same time it will reduce excessive vigour.
More importantly trimming now will avoid the need for hard pruning in autumn – a practice that invariably results in an untidy, woody appearance.

Please keep your questions for Talkback Gardening

Good Gardening  is unable to answer individual reader's questions via email.
If you're looking for specific gardening advice please give me a call on ABC Radio Adelaide's Saturday morning Talkback Gardening  or speak to the experts at your local garden centre.

Talkback Gardening tomorrow

ABC Talkback Gardening podcastsABC Radio Adelaide Talkback Gardening this Saturday, 8.30 am to 10 am – phone Deb Tribe and me on 1300 222 891 and have your own gardening question answered.

After a hot dry finish to spring, what lies ahead in terms of rainfall and heat spikes during summer?
Climatologist Darren Ray presents his regular three-month weather outlook for home gardeners.

Garden centre directory

Leading Adelaide garden centres recommended by Good Gardening newsletter.

Heynes Garden Centre

Heyne's Garden Centre
283-289 The Parade, Beulah Park. (08) 8332 2933
Well its December! Nothing says Christmas more than a beautiful RED poinsettia. Poinsettias are here, there and everywhere at Heyne’s – plus we have some that are just a bit different if red's not your colour.
South Australia's oldest established garden centre. Huge range. Expert staff on hand for personal advice. Visit online »

Semaphore Pets & Garden
Semaphore Pets and Garden
119 Semaphore Rd, Semaphore. (08) 8242 7302
Poinsettias have arrived ready for your Christmas dining table. We are stocked with all the gift items to suit even the hardest to buy for.  Our homeware section is extensive and unique, with a strong emphasis on supporting Australian businesses. We have a new range of Vegan-friendly products as well.
Always has a great selection of plants, pets and giftware – all under the one roof.
Facebook »

Barrow & Bench
Barrow & Bench Mitre 10
321 Unley Rd, Malvern. (08) 8272 8566
Paint your garden red and white this festive season with advanced vincas, petunias & chillies  … pair them with a Rod Manning Sculpture to complete the look.  These & so much more in store now.
Specialises in providing quality plants and expert garden advice. Follow the Instagram feed »
Weather forecasts

Regular garden attractions

Check with each venue's web site for any Covid-19 restrictions on opening hours.

Adelaide Botanic Gardens – free guided walks

Friends of the Botanic Gardens of Adelaide guided walks for the public at Adelaide, Mount Lofty and Wittunga Botanic Gardens, and Botanic Park.
More information »

Carrick Hill

Heritage house museum and garden, the former home of Sir Edward and Lady Ursula Hayward. Open weekends & public holidays. Free admission into garden and grounds. 46 Carrick Hill Drive, Springfield.
More information »

Cummins Historic House and gardens
23 Sheoak Ave, Novar Gardens. Gardens open and plant sales on 1st & 3rd Sundays of each month (except Dec & Jan) 2 pm - 4.30 pm. Plant sales also available every Friday morning 9 am to noon. More information »

Heysen - The Cedars
The historic home of two of Australia’s most noted artists, Sir Hans Heysen and his daughter Nora. This unique 60-hectare heritage estate features the original family home, two artists’ studios and the celebrated cottage-style garden, planted chiefly with exotics, including the massive Himalayan cedar trees.
Heysen Road, Hahndorf. Open 10 am - 4.30 pm, Tuesday to Sunday, and also open on public holiday Mondays. Ticketed entry, including guided tours at 11am, 1pm and 3pm.
More information »

Urrbrae House historic precinct gardens
At the end of Walter Young Avenue, off Fullarton Road, Urrbrae, or from the Urrbrae House gate, Claremont Avenue, Netherby.
Open from dawn until dusk every day. Free entry.
More information »

Waite Arboretum, Fullarton Road, Urrbrae
Open free to the public every day of the year from dawn to dusk, except on fire ban days. Free guided walks on the first Sunday of every month, 11 am to 12.30 pm.
Meet at the West lawn (Croquet Lawn) of Urrbrae House. Bookings not necessary.
More information »

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Disclaimer: Although all reasonable care is taken in preparing information contained in this email, neither Jon Lamb Communications (JLC) nor its officers, staff or suppliers involved in the editing and production of this email accept any liability resulting from the interpretation or use of the information set out in this document. Information contained in this document is subject to change without notice and is of a general nature and should not take the place of professional personal advice. No responsibility is accepted by Jon Lamb Communications for the accuracy of information contained in web sites linked from this email. Publication of an advertisement does not constitute endorsement by JLC of any product or service, or warrant its suitability.

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