Archive for the 'How to plant' Category

Growing and Planting Australian Native Plants

In an earlier post on growing Xanthorrhoea, a comment was made about using milk cartons as a cheap deep pot that will accommodate the root systems of Australian native plants. As a result of that comment, ‘Roughbarked’ sent some very useful ideas on how to actually use the milk cartons as planters and as tree guards. I have been saving milk cartons for a while as I am about to replace a couple of hundred plants, and we have a family of hares and some rabbits. (If I had my way they would all be in the stew pot!) The destructive pests wil eat plants off below the last set of leaves leaving no opportunity for re-shooting, and resulting in the loss of the plants. Commercial tree guards are available, but of course the extra funds spent on these could go on buying plants.

This is the very useful comment made by ‘Roughbarked’.

Milk cartons as pots and tree guards.

I use a knife and stab the cartoon on each of the four faces once, in or near each corner. If you use a knife long enough you can stab right through two sides at once, flip the carton stab it again the same way and the job is done. I also cut the folded top part off so that all cartons have a neat and equal size. The stabbing leaves only slits so the water can drain but not drain too rapidly. Yes, the bottom of the carton will deteriorate and I have often just slipped the old carton off and slid the lot into a new one.

The benefits of milk cartons as a pot for natives are the long straight sides and the corners. The roots will hit the corners and follow the water down to the slits I cut. This creates a healthy root system that cannot become pot bound.

When planting out from milk cartons, I will point out that it is the only useable pot for natives, that does not have to be upended. I just tear or cut the bottom off, grasp the carton by the top and drop it downwards. The plant roots and mix all stay together and slide out into the hole you have dug. The milk carton slides upwards. Stop it just before it slides all the way off. Water and backfill the hole leaving the milk carton as a tree guard. Done with skill, this does not require stakes to hold the carton erect. The carton will remain for up to two years as a tree guard that is biodegradable and will not cause the trees stress by becoming a tourniquet, as some plastic tree guards do.

Growing Eucalyptus From Seeds

Collection of Eucalyptus nuts

Collection of Eucalyptus nuts

The Eucalyptus gum nuts (woody fruits) that are left on the tree after it has flowered, contain seed and chaff. When they have ripened some fall off naturally, or are nipped off by parrots and lorikeets.

These gum nuts can be collected and placed in a container or paper bag and left in a dry place until the valves in the top of the nut open and release the seed and chaff.

Some trees hold the nuts way past the first year. It is always best to take the older nuts as then you will be sure that the seed is mature and will germinate.

Some species of Eucalypt do not set much seed in the nuts, and some seed will not germinate.

Eucalyptus macrocarpa gum nut with seeds and chaff

Eucalyptus macrocarpa gum nut with seeds and chaff

Some easy ways to germinate the seeds:


Use a clean pot, about 100-150 mm across the top, with holes in the bottom.

Seed raising mix

You can buy seed raising mix from garden centres and some large supermarkets. It keeps, so just store it in a clean container, with a lid.

You can make your own with clean (washed) coarse sand and cocopeat.

  • The cocopeat is available from garden centres and supermarkets. The block is the size of a house brick and is made from coconut husks.
  • Half fill a 9 litre bucket with water, place the cocopeat brick in the water and leave it to absorb the water and expand and become moist and crumbly.
  • Use about two parts peat and one part sand mixed together.

Sow the Seed

  • Fill the pot to within 2 cm of the top of the pot and tap the pot on the table to settle the mix.
  • Press the surface of the mix lightly to make it smooth.
  • Sprinkle a pinch of the seed/chaff over the surface of the mix.
  • Sprinkle a very light layer of the seed raising mix over the seed.
  • Label the pot with the name of the species and the date.
  • Labels can be made from the lid of an icecream container, or pop sticks.
130mm pot sown with Eucalyptus macrocarpa seeds

130mm pot sown with Eucalyptus macrocarpa seeds

Caring for the pot of seeds

  • Stand the pot in a container like an icecream container and fill the ice cream container with water.
  • The water will soak up through the seed raising mix and wet the surface of the mix and the seeds.
  • The surface of the mix should be kept moist, not soggy, so once the moisture is there, keep the water level in the ice cream container at about 3cm.

(You could use a fine spray from a hose to water. Be careful that it is fine so that you do not wash the seed out of the pot.)

Seed container in icecream cotainer

Seed container in icecream cotainer

  • Keep the pot in a sheltered, well lit spot, out of direct sun if the weather is hot.
  • Seed should begin to germinate in 2-4 weeks, depending on the air temperature.
  • When the seed has germinated, keep the water level in the icecream container quite low, or remove it altogether, keeping the potting mix just moist.

Planting To Enhance Drought Tolerance

A new book was launched today at the South Australian, Australian Plants Society Autumn Plant Sale. This book is a tool, rather than a list of plants. It provides a process whereby the gardener can establish whether a plant could be grown in their garden given the natural rainfall, soil pH, soil structure and whether any modifications could be made to the growing conditions.

In the words of the author

‘Realistically it provides a simple method of matching plants to your conditions mimicking the intuition good gardeners develop over many years and recognizes a site’s limitations.  Modifications are discussed to extend the range of suitable plants.  It is not limited to native plants nor to Australia.  It benchmarks each garden’s attributes so the process works anywhere in any climate!’

This tool would work well with the lists of plants that have been published, so that the best choices can be made and if that plant must be one of them, it provides ideas for modifying the conditions so that there is a good chance of success. See details for purchasing here.

Growing Banksias

Having written about the frost hardiness of Banksias, I thought I would look at the general growing conditions.

There is a number of species which do very well in the alkaline soils locally and once established, manage on the local rainfall of 334mm a year, falling mostly during the winter.

The first requirement is good drainage. This can be achieved by raising the planting area by  as little as 10cm, more would be safer, if this is a problem. An issue for me is that some parts of the block have little top soil and a planting hole can become a sump 9or like a plasti c pot without drainage holes) when there is clay underneath. I try to break through this and use gypsum in the hope that the overall drainage is improved. Otherwise the raised bed has to be used.

For frost sensitive species it pays to plant during spring to gain the growth and hardiness required before the first frosts in the following autumn.

Like all new plantings, the root ball of the plant needs to be kept moist until the roots have moved out into the surrounding soil. Always make sure that the drippers, if using them, flow onto the root ball. I have had most losses because of this failure.

Planting in Dry and Alkaline Areas

I have been finding plants in the nursery that need to be planted out while the soil is still reasonably warm. There are quite a few, including some very neglected Eucalypts. Thought I would do a list in the blog of plants for our dry situation here. The average rainfall here is 330mm or 13 1/4 inches. Mostly winter falls, and often not heavy at any one time. When we get more than 20 points (5mm) in a day it is a time for rejoicing. We had 40 points last Thursday and the benefit can be seen immediately.

The soil here is mostly very alkaline. Some areas of the town and outlying districts go down to neutral. The soil structure  is quite good apart from patches of ‘non wetting’ or water repellant sand. It is the limestone rubble that is the problem. At least the drainage is good. None of the books will say what plants will adapt to these highly alkaline soil conditions. In fact there are many plants which will grow happily in alkaline soil, even though the books do not say this. It is the highly alkaline soil which makes life a little more difficult. It has to be a trial and error situation. So my list will reflect what I know to be true.

It is worth getting the soil tested. A test kit costs something like $25 and will last for years. If there is an opportunity to have soil tested at a plant sale, take advantage of the offer. Sometimes plants which are acid soil lovers will grow in alkaline soil, even if not to the ultimate size that is listed. Others will look very yellow and deteriorate. There are remedies which will improve this, like iron chelates or sulphur watered in to the soil surrounding the plant. Follow the directions  on the container.

In poorly drained soil it is worth raising the level of the soil by creating small catchment areas and adding the soil to one side in the form of a mound. Planting on the mound will make an amazing difference to some plants. I have heard that the raised area will also decrease the effects that high alkalinity has on some plants.

I will begin the list tomorrow.