From Jon Lamb Communications
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May 15, 2020

Watch out for early-season frosts

Short spells of cold, frosty weather over the next few weeks should bring an end to late-maturing summer crops, particularly tomatoes, cucumbers and zucchinis.
While the current shower and rain-bearing fronts will persist, clear skies and cold air in between the fronts are likely to result in early-season frosts.

Reducing the risk

  • Soils that are damp and bare will absorb more heat during the day than ground that is dry or covered with weeds or mulch.
    In areas where frost is relatively mild (inner suburbs), this is often sufficient to prevent frost damage.
  • On nights when frost forms at ground level, the temperature 2-3 metres above this is likely to be 1-2ºC warmer.
    This is worth knowing if you have frost-sensitive plants growing in containers – lift your plants off the ground and place them on a 1-2m high bench.
Feature plant

Osteos for autumn colour

If you are looking for an instant splash of late-autumn colour, check out the current range of Osteo daisies.
Osteos (or osteospermums) with their daisy-like blooms are now available in numerous eye-catching colours and colour combinations.
In the garden they are hardy, fast-growing, very long-flowering (spring through to autumn) and require very little maintenance.
They also have excellent tolerance to drought, although the soil should be kept moist while flowering.
The plants have a pleasant mounding habit and generally grow 25 to 40 cm high with a spread of 40 to 50 cm.
This makes them ideal for growing either in containers or garden beds.
Osteo 3 D has interesting two-tone colours with a prominent centre.

Osteospermums  are in stock at Heyne's Garden Centre, Norwood, and should be available at other good gardening centres.

New nemesias weather-hardy and very colourful

Four brilliant colours have just been added to the latest “Sweet Treat” series of high performing perennials nemesias.
Sweet Treat Nemesias produces large, strong, bicoloured flowers that stand tall above their bushy but compact foliage (20 to 30 cm).
Apart from their colours their perfume is quite divine.
These nemesias will be in full flower from May through to November and spot flower after that.
A light trim and a little fertiliser after each flower wave will encourage rapid re-blooming.
Sweet Treat Nemesias have been selected for their ability to withstand strong winds and heavy rain.
These are sunlovers and produce excellent results in pots, baskets and garden beds
Incidentally the colour range is now extensive and includes Coconut ice, Blackberry, Raspberry and Lemonade, Banana Split, Plum and Custard and Rhubarb and Custard.

Nemesias are in stock at Heyne's Garden Centre, Norwood, and should be available at other good gardening centres.

   Getting ready for a wet winter   

Drainage critical in clay soils

After weeks of showers and soaking rain, moisture is now seeping well below the surface, re-wetting parched subsoils.
However, soils that contain a high percentage of clay (this includes almost 2/3 of the Adelaide region), particularly if they are compacted by constant foot traffic, will drain slowly.
Just as importantly they will contain insufficient air for healthy root growth.
Fortunately there is a cost-effective remedy at hand – gypsum.
Gypsum is finely crushed natural rock that sticks the clay particles together, significantly improving both drainage and aeration.
Simply spread the material (1 kg/m²) over the area and let the next rain wash it in to the topsoil.
The reaction is rapid and you should start to see a significant improvement within days.

Colour for winter gardens

The last autumn leaves are about to disappear and soon there will be little colour remaining in many gardens.
The quickest answer is to pay a visit to your local garden centre – before the last leaves fall – and select a few potted plants already in flower. 
Chrysanthemums, cyclamen, perennial nemesias and Federation daisies will all provide long-lasting winter colour.
You will also find an interesting range of bloomers on sale.  Bloomers are flowering annuals grown in individual pots under special conditions to induce early flowering. 
The range includes pansies, violas, snapdragons, primulas and polyanthus.
More on caring for your bloomers in my Advertiser gardening column, tomorrow.

These vegetables thrive when it’s cold

If you are thinking of planting vegetable seedlings this weekend you’ll be happy to know garden centre supplies are almost back to normal.
However, because soil temperatures have dropped significantly over the past two weeks (14 °C to around 11°C) it is worth giving highest priority to vegetables that thrive when it’s cold.
Hybrid cabbage such as Superette should be top of the list, as seedlings planted now will be ready to harvest in 10-12 weeks.  If they are spaced 40 cm apart, you can plant your punnet of 6-8 seedlings in a relatively small area. 
Larger headed varieties, including Ballhead, take a few weeks longer to mature and should be spaced 60 cm apart.
Broccoli is just as easy to grow with Green Dragon, spaced 45-55cms apart, also maturing in 10-12 weeks.
Broccoli produces a single large green cabbage-like head, but once this is removed, the plant will produce side branches and numerous small heads.
Cauliflower, particularly the larger-headed varieties such as Westralia and Pale Face, are slow to mature (16 weeks) and it’s worth seeking out quicker-maturing, smaller-headed varieties.
Lawn Care – Stefan Palm

Keeping your lawn green this winter

A run of cool days and cold nights has certainly slowed the growth of summer active grasses such as couch grass, buffalo and kikuyu.
The challenge for all good gardeners is to keep the grass green during winter.
In this week’s lawn blog turf consultant Stefan Palm suggests it is possible to keep the grass greener than you think.
However, it helps to understand the many factors that are currently at play.
If you are ready for the “Green Lawn this Winter” challenge, take a look at what Stefan recommends.

More information »
Paul Munns Instant Lawn

Autumn leaf trees for warmer districts

What trees with good autumn colour grow well on the Adelaide Plains and in warm country districts, while fitting into a small courtyard garden? 
Weeping Crab-apple (Malus Ionises) is my first choice, particularly the double flowered form M ‘Plena’. 
You can expect brilliant blossoms during spring, followed by small orange red fruits or ‘crabs’ that hold on the tree until autumn, when the large leaves turn a golden yellow. 
M ‘Gorgeous’ produces single blossom and masses of bright red fruits.
Chinese Tallow Wood (Sapium sebiferum) – this attractive tree thrives in hot dry climates, producing a rounded shape 4-7 metres high. 
The leaves are quite large and heart-shaped, producing golden colour in autumn.
Golden Rain Tree (Koelreuteria paniculata), another attractive and very adaptable tree that thrives best when it is not overwatered. 
Expect masses of yellow flowers early in the growing season, followed by unusual paper like seedpods during summer and autumn.  As the season breaks, the leaves turn yellow and golden brown.
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Sweetening sour oranges      

There is nothing like a spell of cold weather to put colour into your ripening navel oranges.
If the fruits you are picking taste a little sour leave them on the tree for a week or so as cold temperatures will also increase their natural sugar content.

Growing cyclamen from seed

If the thought of growing your own cyclamen has appeal, autumn is the time to start.
Seed sown into a quality seed raising mix should be ready for potting on into small containers during spring.
These plants will begin flowering in the following autumn.
Seed is readily available from online retailers.

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

Composts and garden rock dust
Organic gardening authority, Tim Marshall discusses composts and leaf mulch for small gardens and is there a need in the garden for rock dusts?

Garden centre directory

Leading Adelaide garden centres recommended by Good Gardening newsletter.

Heyne's Garden Centre
283-289 The Parade, Beulah Park. (08) 8332 2933
South Australia's oldest established garden centre. Huge range. Expert staff on hand for personal advice. Visit online »
Weekend gardening weather

Garden events and shows cancelled

The COVID-19 situation has forced the cancellation of numerous garden events and shows.
All current and coming events listed in recent editions of Good Gardening have been cancelled.

Regular garden attractions

Some of our listed regular attractions may have closed or have limited access, due to the COVID-19 situation.
Please check with the relevant organisation.

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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