From Jon Lamb Communications
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January 15, 2021

Trees of choice for Adelaide’s small gardens

Drive through Adelaide’s outer suburbs in the next few weeks and you’re sure to see rows of small attractive trees absolutely smothered in pink or red flowers.
The trees are “Indian Summer” crêpe myrtles and, because of their tolerance to extreme heat and ability to thrive in a wide range of often hostile soils, they are quickly capturing the hearts of SA gardeners.
Indian summer crêpe myrtles have outstanding resistance to powdery mildew. Flowering begins early in January and often continues through to mid March.
In autumn, the leaves colour well before falling, revealing very attractive smooth patterned bark.
As gardens become smaller and with growing concern over our warming climate, crêpe myrtles should be right at the top of our landscaping planting list.
Some of the best smaller varieties include:
  • Acoma  3 m –white
  • Lipan 4 m – pink
  • Sioux 4.5 m – hot pink
  • Tonto 3 m – fuchsia pink
Taller varieties:
  • Natchez 5m – pure white
  • Tuscarora 5 m – fuchsia pink
Diamonds in the Dark is an outstanding new series, featuring foliage and bark that is nearly black, while the canopy is compact and upright (2.5 to 3 m.) Colours in vivid pinks, orange and white.

SA gardeners adapting quickly to climate change

Damage from last week’s heat spike has again been relatively light, indicating SA gardeners have been quick to adopt heat-related climate change strategies, including more frequent watering, mulching and shading.
Apart from a few scorched leaves, the main damage appears to be heat stress to small plants growing in relatively small containers – located in the sun.
In this situation, the plants have not developed a large enough root system to keep their leaves supplied with water during very hot weather.
If possible move these plants to a shady location before the next heat spike later this month.

Recovery after heat stress

Plant recovery after a heat spike can be accelerated considerably by soaking the plant's root zone with a seaweed solution – either liquid (Seasol) or powder (eco-Seaweed).
At the same time add a soil wetting agent (liquid or granule).
These are very effective in improving the ability of water to soak thoroughly through the root zone of plants.
Soil wetting agents are not harmful to plants or soil microbes and quality brand products (various) will remain effective for 10 to 12 weeks.
Fertilisers should not be used to stimulate heat-affected plants, until there are definite signs of new growth.

More hot weather coming

Enjoy the current spell of mild to warm weather as SA’s independent climatologist, Darren Ray, expects hot weather will return later next week with the potential for 40ºC plus temperatures.
Feature plantsof the week

Vinca Tattoo – colourful and unique

Tattoo is without doubt, the most remarkable vinca on the market today.
Each flower looks like it has been airbrushed with soft black highlights, making a stunning and long-lasting potted display and perfect for edging or bordering a pathway.
This is an upright type of Vinca, with spectacular flowers that thrive in hot and sunny conditions.
Each plant is very well branched, producing an endless display of colourful flowers that have an overlapping but fully-rounded form.
Tattoo Vincas grown by Easy Colour are available in four colours – Black Cherry, Papaya, Raspberry and Tangerine.
Look for Vinca Tattoos in the distinctive Easy Colour purple 4 cell packs
Easy Colour
Vinca Tattoo are in stock at Heynes Garden Centre, Norwood , Semaphore Pets & Gardens and Barrow & Bench, Malvern and should be available at other good gardening centres.

Rockin Salvias never stop flowering

If you are looking for a plant that is always in flower – consider a Rockin Salvia.
Because the bushes never stop flowering (in Adelaide and warmer districts) Rockin Salvias are extremely showy.
The flowers also provide a constant source of nectar and pollen to honey birds and bees.
There are currently two varieties, Rockin Deep Purple (above) and Rockin Fuchsia (right).
Both are extremely hardy and once established they have excellent tolerance to drought.
They also thrive in the sun, adapt well to semi-shade and compete well against the root system of nearby trees.
These salvias adapt well to both formal and informal plantings and look great on the patio growing in a large decorator pot. In mixed garden plantings they hold their own well.
The bushes can be pruned to size at any time, while they are making active growth.
Under average conditions they will grow 1.2 m high and almost as wide.

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

Keeping plant roots cool

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 very 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.
Needless to say, covering the ground with a thin layer of mulch (2 to 3 cm) can significantly reduce the amount of moisture lost through evaporation.
During very hot weather mulch also has the ability to reduce soil temperatures by 10 to 15°C.

The value of shade

On a hot day when daily temperatures approach 40ºC, don’t be surprised to find topsoil temperatures in sunny parts of the garden reached 50°C and more.
When soil temperatures exceed 32°C, plant root growth is reduced.
At 40 to 45°C, plant root tips are damaged and begin to die.

Home trials show importance of shade

Last Sunday I carried out a few trials using potted plants in my own garden.
The plants – well-established vincas in 20 cm pots – were located either in full sun or full shade (large tree).
Soil temperatures were recorded (using soil thermometers) at five and 10 cm depth. (This is where 60 to 70 percent of plant roots are located)
Soil depth Topsoil temperatures Comments
Sun Shade
At 5 cm 45° C 30° C Plants in sun wilting, signs of severe stress. Those in shade unaffected.
At 10 cm 40° C 28° C Plants in sun starting to wilt. Those in shade unaffected.

Two top climbing roses for 2021 – pre-order now

Climbing roses not only produce great colour in the garden they also provide gardeners with a number of valuable planting opportunities.
Tall varieties can be used to cover walls or featured on pillars, archways and pergolas. Smaller varieties can also be grown in large containers.

These two roses are now available for pre-order Knight's Roses' website.

A beautiful nostalgic climbing rose with large flowers. As the blooms open the colour changes from rose to apricot with a hint of peach.  These have a rich sweet-spice scent. (2 m x 3 m)
A climbing rose with intense rich red blooms. These are long lasting and open to a large size with plenty of petals. Glossy foliage and very disease resistant. (2 m x 1.8 m).
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.

Don’t ignore leaves turning yellow

If the leaves of your favourite tree or shrub have turned yellow instead of green, suspect either a nitrogen deficiency or lack of iron due to too much lime in the soil. 
Try an application of nitrogen fertiliser first and, if the plant does not respond within 2-3 weeks, spray the foliage with iron chelates.
This is available from most nursery outlets.
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Why some tomatoes have black bottoms   

Blossom end rot (BER), a black leathery distortion on the base of tomatoes, is turning out to be a common problem this season.
This disorder appears when plants are unable to absorb sufficient calcium from the soil.
Movement of calcium (dissolved in the water and absorbed by plants) is completely dependent on the plant's ability to absorb and transpire sufficient moisture.
If there is insufficient moisture – the soil dries out on a hot day – the supply of calcium to the rapidly-developing fruit is disrupted.
When this occurs, the cells at the base end of the fruits begin to break down.
Experienced gardeners have learnt the secret of managing BER lies in keeping the roots of tomato plants moist at all times by regular watering and mulching. 
Treating the soil with lime at this stage does not help, as calcium in the lime is not readily available to the plants,

Harvesting garlic       

Garlic bulbs need maximum sunlight and warmth at this time of the year to assist with their maturity. Needless to say, in many gardens, maturity is running late.
For long storage, wait until leaf colour turns from green to pale yellow.
However, before digging it is important that the plants bulbs sit and bake in the sun for 3 to 4 weeks to cure.
Withholding water as they cure will help.
Keep the plumpest cloves for planting out next season.
Lawn Care – Stefan Palm, Paul Munns

Sound advice if you are installing instant turf

When it comes to rolling out instant turf,good preparation holds the key to establishing a lawn that is hard wearing and drought tolerant, as well as looking good.
As a lawn consultant, Stefan Palm deals with a wide range of issues related to installing instant turf.
In this week’s lawn blog Stefan considers some of the important soil related issues, such as can you establish a lawn on your existing topsoil, what is the recommended thickness if you are bringing in topsoil and what is the best sort of soil to buy?
More information »
Paul Munns Instant Lawn

When do your pot plants need watering?

Knowing when to water is important. But getting it right is not easy.

Watch the drainage holes
A good guide to your watering efficiency is to watch the containers ‘drainage holes.
If you apply a considerable quantity of water to the surface of a medium to large container and it runs out the drainage holes in less than 30 seconds, you have a serious water repellence problem. I.e. the water is running down the sides of the root ball rather than diffusing evenly through the root ball.
This problem is easily managed by spreading a soil wetting product over the surface.

Try the pot-lifting test
A relatively small container plant just watered is quite heavy. The same plant in a similar container when dry is surprisingly light.
If the container is light when lifted the plant needs watering, but if it is heavy there is still plenty of moisture remaining in the root ball.
For small pots lifting is a quick and very reliable guide to whether your plants need watering.

The finger test is also reliable
Feel the potting mix 1 to 2 cm below the surface. If there is moist soil on your fingers after the test, there is still plenty of moisture below – don’t water.
On the other hand when the soil on your fingers looks dry it’s time for a good soaking.

Houseplants happy with humidity

Most indoor foliage plants prefer humid conditions around their leaves. 
To achieve this during summer, place the plant on a saucer containing pebbles or gravel, filled with water. 
The evaporating water will increase humidity around the plant.

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 Leigh Radford and me on 1300 222 891 and have your own gardening question answered.

Turf consultant, Stefan Palm, discusses rolling out instant turf and watering lawns in summer.
Weather forecasts

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
Just landed! Two stunning new compact mandevilla varieties: Tourmaline ‘Intense Fuchsia’ and Jade ‘Orange Coral’, perfect for hanging baskets and pots for some serious wow factor in your entertaining areas!
Available in store NOW! See you this weekend.

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
The trucks have been rolling in full of loads of fresh fruit trees, beautiful indoor plants and a scrumptious range of indigenous edibles. We are full of fabulous things to see and buy. Unpacking new indoor pots as we speak. See you soon.
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
Normal service has resumed – the growers are back!  Our garden centre is stocked full.  Indoor plants are back and the perennial and ‘wow’ plants are looking amazing. 
Be sure to stop in and speak to one of our ‘mighty helpful’ staff,  who are always happy to assist you in creating your perfect garden oasis.

Specialises in providing quality plants and expert garden advice. Follow the Instagram feed »

Coming soon

Saturday & Sunday, April 10 &11
Autumn Plant Sale - Australian Plants Society (SA Region)
Adelaide Showgrounds, Wayville.

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 and 2 pm.
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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