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!

Mealybugs

Jean De La Bruyere mentioned that "The first day one is a guest, the second a burden, and the third a pest".

The above mentioned quote relates to garden pests and in particular mealybugs.

Over the past year I have come across 3 cases of mealybugs effecting Daphne odora plants in various suburbs of Melbourne.

Mealybugs, depending on species, are oval, grey insects that grow up to 4mm in size.

Mealybugs grow in colonies; they are covered in wax and can easily be mistaken for fungi.

They thrive in warm, moist conditions, especially in protected places.

Given the previous comment and the weather conditions in Melbourne, of late, it does make sense that mealybugs appear at higher frequency.

The damage that mealybugs cause is wilting of growth and new leaves can be distorted.

Ants are the "transporters" of mealybugs and it is one of the first signs that gardeners need to be aware of.

If and when comes to chemical control, Malathion is recommended.

Principles of garden design for Poetry in Gardens

The following principles are engaged for the design of gardens by Poetry in Gardens:

•     Balance
•     Rhythm
•   Colour
•    Texture
•    Space

Balance

The concept of balance is based on the comfortable feeling of stability brought about by the way in which the area is divided up and the various visual weights are distributed throughout the garden area. 

Rhythm

In a visual design sense, movement is conveyed when the eye is led along from one area or point to the next. If this feeling of movement is repeated over and over then the design becomes more rhythmic. The elements which affect rhythm in major ways are line and form and to a lesser degree space, pattern, texture and colour.

Colour

Colour comes to us combined with every shape, size and texture and as a part of every material we use in the making of a garden. Colour has an amazingly potent impact on human emotions and thus becomes one of the best elements for creating particular moods and effects.

Texture

In garden design, textural concerns are more to do with the overall surface of whole plants rather than that of each leaf or petal. The overall texture of plants can play a significant role in setting the garden style.

A small quantity of string contrast in plant texture can be one tactic that helps give a garden real personality.

Space

Garden space can be characterised as static as there is no visual movement. A static space is one of the most contrasting elements that can be used in a garden, therefore the selection of plants will create a complementary aspect to the existing space based on the texture, colour, and rhythm as mentioned above.

In cases of large gardens, space allows plants to mature and appreciated in full size. Large shrubs and trees add character to large gardens by utilising space.