Archive for the 'Soils and Potting Mixes' Category

Chamelaucium (Geraldton Wax)

I’ve been to a Women’s Craft Camp this weekend indulging myself in some relaxing hand sewing while making a small sewing box called an etui. There were 72 women booked in at this camp called ‘El Shaddai’. The site is not far from the River Murray at Wellington SA and has been made attractive over the years with wind break plantings and gardens around the site.

I remember years ago when this site was begun how much difficulty there was in planting trees and shrubs. There is sheet limestone everywhere and planting holes were actually blasted.

Chamelaucium 'Meringur Mist'

Chamelaucium 'Meringur Mist'

Chamaelauciums (Geraldton Wax) have a habit of becoming a little yellow in the foliage when the soil alkalinity is too high. This one was looking very good.

The garden soil has certainly been improved and I was surprised to see a few plants there which usually take on a yellowish tone in the highly alkaline conditions actually coping well with the conditions. It proves that the high pH situation can be improved with some attention given to good garden practice. In this case, garden beds have been raised and composted materials added and mulch has been applied over the years.


Growing Plants In Pots

Verticordia plumosa (Feather Flower)

Verticordia plumosa (Feather Flower)

We had unseasonal fierce, hot winds and temperatures last week and a few of my stock plants were scorched badly. A couple of pots had become non-wetting so that when I watered the water passed straight through the pot in channels and also ran down the sides between the pot and mix. This water repelling can be treated with a soil wetter and I used a granular one which has been very effective.

However, in ‘Gardening Down Under’, Kevin suggests that potting mixes are designed to be used in pots to 125mm across and that clean soil should be used in tubs 225mm and larger. I have been thinking about this. I have a load of sandy loam and I think I will try a 50:50 mix of loam and potting mix in the large pots. This way I will still get reasonable drainage and water retention. It won’t stop the pots from heating up. I will need another strategy for that. The other problem is the weight of the pot. At least I will not be wanting to move them often.

The plant in the photo is one of the forms of this Feather Flower. These are sought after by florists. I have never been game to try them in the ground here, as in the wild they grow in fairly deep sand. This would give them very good drainage. Whether the sandy loam/potting mix mixture would work for them is debatable. I want to make a raised bed to try them as well.

Useful Book On Gardening

Kevin Handreck’s book, ‘Gardening Down Under’, is another publication of the CSIRO in Australia. Its ISBN is 0 643 05511 8. I found a lot of treasures in it that I had forgotten about. Some are:- different potting mix recommendations for different sized pots, fertilisers for soils and potting mixes, watering regimes, gardening and salty water, raising and lowering soil and mix pH.

He is not only practical in his approach. He also gives the science behind the practical measures he recommends.

With the drought conditions in Australia at the moment, any information about efficient use of water is welcome. There are a lot of recommendations and reasonings in this book which make sense.

Lowering pH of Soils Information

I had the opportunity to hear Kevin Handreck speak about soils at the Australian Plants Society Flower Show and Plant Sale. Kevin is a well respected soils scientist and author of a number of small books for the CSIRO. He also wrote the book ‘Gardening Down Under’-Better soils and Potting Mixes for better gardens. I highly reccomend this book to all gardeners.

Instead of speaking in general terms about soils, he asked the audience what they would like him to discuss. Well! My first question was about dealing with highly alkaline soils. Bless the man, he spent quite a while discussing strategies.

As Kevin said, the obvious solution is to use those plants that don’t mind those conditions. However, for the rest of us who want to try other plants, he offered some possible solutions to try. One I think is a distinct possibility. Under the drip line of the plant make 3 or 4 holes (depending on the size of the plant) and fill with a mixture of cocopeat or potting mix or peatmoss and ferrous sulphate (10 litre cocopeat to 1 cup ferrous sulphate) and cover with a layer of soil.

As an extension of this, I wonder if it would also work to remove the soil from the planting hole, place the plant, add the peat mix to the soil and back fill with it. It is worth experimenting.

Potting Mixes For Propagating Plants

One of the most frustrating things about propagating plants and growing plants in pots is finding the right ingredients for potting mixes.

In the previous post Make New Plants… By Taking Cuttings, I mentioned obtaining a propagating mix. I have had to compromise with what is available locally. The basic idea of a propagating mix suitable for cuttings is to have excellent drainage, one that does not compact with watering, and maintains some moisture.

Traditionally, coarse sand mixed with peat moss was used. The difficulty is where does one get coarse sand? One of the potting mix companies now markets bags of coarse propagating sand. Whether you can buy it locally is another matter. Other ingredients readily available are blocks of coco peat (more environmentally friendly than peatmoss), vermiculite and perlite both of which are used in hydroponics. My compromise is a mixture of a reasonable bark based potting mix, coco peat and either perlite or vermiculite, in about equal proportions and moistened.

The main thing to do is to work on a recipe and if it works continue to use it. The most important consideration is to use clean ingredients.

Equally as important is to always mix the ingredients in the open and take care when opening bags of potting mix. Perlite floats. It can be a pest to use. A mask is a good idea as some people have been known to contract Legionnaires disease from dry potting mix floating in the air. Keep potting mix moist rather than allowing it to become powder dry.

No.2 of a series on Propagation