The Gardens at Hartley Hill

The Rainforest Garden

The rainforest garden was initially planted in 1998. The soils were nutrient poor grey clays with very poor penetration of water. It was impossible to dig in them with a spade. To improve the soil we had 50 cubic metres of leaf mulch spread to a depth of about 20 cms. This compost had a number of benefits, namely:

The compost added a considerable quantity of nutrients. Some people are reluctant to add leaf mulch as they have heard that it robs the soil of nutrients. The nutrients are only removed for the short term. As the mulch breaks down the original nutrients, plus the extra nutrients from the mulch, become available for the plants, in the quantities and proportions that native plants prefer.
The fungi that decomposed this mulch penetrated the soil to a depth of about 30 cms. This was visible as fungal hyphae if we turned the soil. These hyphae produced micropores through the soil that water could then penetrate. The hyphae also moved nutrients and organic matter from the surface compost into the soil.

This compost suppressed weed growth and was effective for about 3 years when the process was repeated again in 2001. By this time the soil was darker in colour and becoming moisture retentive. It was becoming possible to dig. At this time two forms of native violets were planted in the garden, they were the common form (Viola banksii) and the darker flowering local native violet (Viola hederacea). These have provided a living mulch over most of the garden.

The mulch was again replaced to a depth of 20 cms in 2004, and the soil is now similar to rainforest soil with its beautiful texture and moisture holding capacity. The plants grow very well indicating the soil also has a good nutrient balance. The soil is extremely rich in worms and grubs, and we commonly see evidence of bandicoots foraging at night.

The plants in this garden grew extremely slowly for the initial five years. However by about 2003 the soil had improved sufficiently for strong growth.

My favorite trees in this garden are:

Blue Quandong (Elaeocarpus grandis) - This is a grand rainforest tree that is stately even when it is not in flower. It is even better in flower and birds and possums love the large white flowers that hang below the branches. The seeds can be used by children as marbles or Chinese checkers.
Euodia elleryana - This is another grand rainforest tree that has a stately form. It produces beautiful pink bunches of flowers along the top side of the branches. The flowers attract birds and butterflies. The seeds are sought after by birds.
Native Citrus (Citrus australis and Citrus australasicus) - These have proven slow growing but are now almost mature and should fruit soon.
Cabbage Tree Palms (Livistona australis) - The cabbage tree palm has very spiky leaf stems, which we use to advantage. I have a cluster of 15 of these palms growing around a pile of logs. The spiky foliage ensures no dogs, cats or foxes hunt there for the lizards living within, mainly the Land Mullet (Egernia major).

The Red Wattle Birds have nested in the large Native Hibiscus tree and Ringtail Possums visit this garden most nights. We have also covered large ceramic pipes to provide homes and retreats for native animals. The rich mulch and living groundcover encourages insects which form the basis of the food chain for animals living in this garden.

There are many other interesting rainforest trees listed below.

The Specimen Garden

The specimen garden was developed as an experiment in 2004.

I had always wanted to grow plants that are considered difficult in this climate, but to do this required a special environment. The biggest problem was our higher rainfall. If I could create a garden with high light intensity the plants would have more active photosynthesis, and thus could expel excess water taken up by the roots. This garden was also given exposure to the westerly aspect for more light and drying effect, and next to a verandah which again produced a warm and dry microclimate. The soil is white sand over a layer or organic sand on a bed of shale rock.

This garden has been very successful as the photographs show. It has had its successes as well as failures. The biggest challenge is to have restraint and not overcrowd this garden. Air circulation is very important to dry the surface soil and thereby control fungal infections.

My favorite plants in this garden are:

Goodenia species I have grown from seed collected near the headland at 1770, near Rockhampton.
Banksia serrata dwarf form.
Dampiera species with grey leaves.

Lawns

We have reasonably large lawns at Hartley Hill. Many native gardeners are anti lawns, and while I can understand their sentiments we have decided to have large areas of lawns. The arguments against lawns is their water and fertilizer requirements, with resultant runoff, and the space taken that could be devoted to native plants.

We counter this as we collect all our rainwater. We have over 150,000 litre storage capacity, and we use very little fertilizer, and we have plenty of space for native plants.

The story of our lawns is:

When the site was leveled, we had an exposed rock surface. Onto this we had over 400 tonne of beach sand placed. Beach sand was used as it was the cheapest. This was leveled with the tractor so it was about 10 cms deep. Onto this turf squares were laid. Complete cover with turf was too expensive so we cut turf into squares and laid it out in a regular pattern. As it was on beach sand regular watering was required, and we had a few fierce wind storms that blew sand through the house. It took two years before we had complete turf cover, but we didn't mind being patient. For the first three years we did not use a grasscatcher when mowing, to build up the organic component of the soil.

Today the soil is a rich dark brown, and is perfect for growing anything. However it is only five to eight centimeters deep, indicating the amount of wind and water erosion we experienced while establishing the lawn. We have to water our lawn regularly because of the shallow soil being over rock, but any excess water runs level and is not lost to the subsurface layers.

Our lawns have the following trees:

Jacarandas - we have a row of Jacaranda trees in the lawn along the front of the house. The first four are purple Jacarandas, then two white flowering trees at the front door, then another eight purple Jacarandas. The Jacarandas are slow growing as they are in shallow soil and suffer from the summer dryness. The white Jacarandas flower each year. Flowering slows the growth of these trees, and being an albino form also results in a plant that is less robust, so these plants are not as tall as the others.

The grasses in our lawns are:

Dwarf Buffalo - our front lawn is a mix of Dwarf Buffalo and Couch grass. Dwarf Buffalo is great as it requires much less mowing. Unfortunately the same characteristics that dwarf the top of the buffalo grass also dwarfs its roots. Because of this Dwarf Buffalo varieties have very little drought tolerance. The Dwarf Buffalo in our lawn is very variable in its success, performing very well when well watered, but dying back when it is dry or cold.

Shademaster Buffalo - We received a quantity of Shademaster when an unscrupulous supplier substituted this instead of Sir Walter Buffalo. The Shademaster is an average performer, and I would not recommend it.

Sir Walter Buffalo - This seems to be one of the best varieties on the market at this stage. It is a very strong growing form, which stays green in winter, has a degree of tolerance to Roundup type herbicides (but we have not tested this), and is capable of crowding out weeds. This all appears to be true, but I am also not fond of the deep thatch that some Buffalo lawns develop into. For this reason we have a dethatcher to thin our lawns. We cut our lawns back severely a few times a year. Due to the high cost of Sir Walter we have limited its use to areas of strong erosion, but we have put runners through other lawns and expect it to eventually dominate there.

Couch - we have a few couch lawns. I am not fond of couch as it invades gardens (where it is difficult to eradicate) and is not as green as the other grasses. However it can look good and has considerable drought tolerance. It is also quick to establish and cheap to buy. For these reasons our orchard and tree fern lawns are couch.

Lawn clippings - Lawn clippings are great compost. They are rich in nutrients and break down easily. We often leave lawn clippings on the lawn, especially on lawns that need improving in fertilizer and soil structure, such as the orchard. Otherwise we use lawn clippings around rainforest trees such as Palm trees, or the Blue Quandong and Euodia trees along our driveway.

Rockery

60 tonne of rock, 70 tonne of sand.