Climbers

Climbers are a unique group of plants with distinct characteristics that can add value and diversity in any garden. One of the most common characteristics of climbers is their ability to grow vertically and sometimes horizontally against man-made structures such as against fences, house walls, posts, wire/trellis, or even other plants such as tree trunks. Climbers have developed various leaf and stem modifications that assist them to grow (climb). These modifications include stems, leaf apices, petiole, tendrils, hooks, aerial/adventitious roots and in some cases sucker discs that reach out to any object that will assist them to grow.

Over the past 17 years of horticulture practice at Poetry in Gardens, climbers have been used to cover fences and walls or create a floral display by growing against pergolas and arbors. Clients, in many instances, perceive climbers as plants with limited use. Nowadays, climbers are used more extensively in landscapes and in urban horticulture projects that include concepts such as “green walls” and garden beds with mass planting of fragrant climbers. Each case is unique to a number of plant and site characteristics including soil conditions, sun aspect, surrounding vegetation, space for growth and support as well as maintenance and access to water.

 Fig. 1 below showcases a Wisteria sp. in full flower that is growing in a support system between two posts. The objective is to add vertical plant foliage and flowers that complement and enhance the garden theme.

Fig. 1 Wisteria sinensis (Chinese wisteria) Balwyn North.

In Fig.2 we see a trellis system against a brick wall that acts as a support system for Hoya sp. to grow. The site of the garden is in shade and there is minimal space for growth of other plant species.

Fig. 2 Hoya carnosa (Wax Plant) Balwyn North.

Fig. 3 Illustrates the effect of a prolific Chinese Jasmine that grows alongside a carport. When in full bloom the Jasmine “steals” by-passers and neighbours attention with its vivid colour and fragrance.

Fig. 3 Jasminum polyanthum (Chinese Jasmine) Montmorency.

In Fig. 4 a Star Jasmine is growing in pots against a wire system that has been installed in an “X” shape to cover the wall of a small court-yard.

Fig. 4 Trachelospermum jasminoides (Star Jasmine) Albert Park.

Organic and biodegradable mulches

Soil profile at Montmorecy, Melbourne. The addition of compost has improved the physical characteristics and soil structure.

Organic and biodegradable mushroom compost.

Mulching, for domestic and public gardens, is considered the spreading of substances over the ground aiming to protect plant roots and soil from environmental factors such as high temperature, rain, erosion and strong winds. This blog post is focused on the type of mulches and what we have learned over the years of applying mulch.

The most common mulch that we have used over the past 20 years is organic compost and in particular mushroom compost. Also, various mulch mixes of manures and organic matter have been used.

In principal, organic mulches derive from plant material and decomposition does occur, and several important effects on the soil and on plant growth will be apparent to home gardeners. These effects are physical, chemical and biological. Physical effects improve soil structure and composition. Mulches alter the structure of the soil which usually increases root growth. The addition of organic mulches to the soil brings an almost immediate effect. Aeration is improved in clay soils, and the water-holding capacity is increased in sandy soils.

The acidity or alkalinity of soil (pH) may be somewhat affected by the use of organic mulches. Given that organic mulches are composed of plant materials, they add small amounts of nutrients to the soil through decomposition. These amounts have little effect on the nutrient level in the soil and should not be considered a substitute for fertilizer.

The biological effects of mulching are important since organic mulches serve as food for many microorganisms in the soil for maintaining and promoting soil aggregation. An additional benefit of organic mulch is that it also helps keep the soil temperature stable so that the activity of the microorganisms can continue despite unfavorable environmental effects.

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Plants growing in confined spaces

In many cases of urban horticulture practice and domestic gardens, plants grow in conditions that are not optimal. These conditions are soil quality and quantity, nutrient availability, light exposure, surrounding vegetation, surrounding buildings and water availability. Plants will compete for water, light and nutrients and in confined spaces, this competition, may have adverse effects on certain plant species.

In a case such as the planting arrangement below (see photo), an elm tree (Ulmus procera) is the dominant species in a corner garden bed that includes maple trees (Acer palmatum), Azalea sp., and start jasmine climbers (Trachelospermum jasminoides); the plants grow within the restrictions of the garden bed.

During summer, the garden bed requires additional watering as the area within 2 meters from the Elm tree is drier than the rest of the garden. Also, the plant species included in the photo are experiencing slower growth in comparison with same species in another part of the same garden.

Belowground competition occurs when plants decrease the growth, survival, or productiveness of neighbour hooding plants by reducing available soil resources. Competition be-low ground can be stronger and involve many more nearby plants than above ground competition.

Belowground competitive ability is correlated with such attributes as root density and surface area either in root growth or in the properties of enzymes involved in nutrient uptake. Unlike competition for light, in which larger plants have a disproportionate advantage by shading smaller ones, competition for soil resources is apparently more symmetric. Belowground competition often decreases with increases in nutrient levels, but it is premature to generalize about the relative importance of above- and belowground competition across resource gradients. Although shoot and root competition are often assumed to have additive effects on plant growth, some studies provide evidence to the contrary, and potential interactions between the two forms of competition should be considered in future investigations.

Plant growth competition.

Much of the competition among garden plants takes place underground. In contrast to above ground competition which primarily involves a single resource, light, plants compete for a broad range of soil resources, including water and essential mineral nutrients in the soil. Below ground competition often reduces plant performance more than does above ground competition.

The above photo indicates the  primary importance in below ground competition is the occupation of soil space. The ability to occupy space depends on several root characters, including relative growth rate, biomass, fine root density, and total surface area.

Openings in the below ground root zone activity are likely to be important for plant establishment. The extent to which root gaps are associated with canopy openings and the role of root gaps in the dynamics of gap succession have only recently been researched.

Plant pests in Spring

Evidently, the day length has increased and we are experiencing higher temperatures. As a result, plants receive more sun light, based on the orientation of the garden bed, courtyard, balcony, etc., and new growth appears in the form of flower buds, stems and leaves.

Insects are cold-blooded animals, meaning that their body temperature is similar to that of their surroundings. They do not maintain a body temperature as do mammals and birds. Most insects do not develop or function well at temperatures below 10 C. This base temperature varies a few degrees up or down, depending on the insect species, but is near 10 C for most insects. When the temperature hangs between freezing (0 C) and 10 C, insects typically go into a dormant state in which body functions are greatly slowed down.

When temperatures are around 10 C for an extended period in the spring, plants continue to expand leaves and grow stems, and they can get ahead of their insect pests that are present but not developing. As a result, insect pest populations may be typical, but plant damage caused by those pests may be much less than normal.

Insect populations typically do not emerge at once. Some insects hatch from overwintering eggs or emerge from overwintering pupae early, and some of the same species emerge later.

The life cycle of plant pests becomes important as it provides gardeners with information on how to treat plant pests. As all insects hatch from eggs, they are short-lived and in some exceptions some insects can produce two or more generations per season e.g. aphids. Therefore, proper and timely identification of insects can assist in treating garden plants with greater success.

Happy Gardening!