Blue Magic

Class

Dicotyledons

Division

Angiospermae

Family

Asteraceae or Compositae

Order

Asterales

Genus

Ageratum

Species

houstonianum

Description

An ornamental herbaceous plant with a compact growth habit; its low, globular form makes it suitable for use in landscaping, in flowerbeds and borders, where it creates uniform, colourful clumps, and can also be combined with other species of varying heights to create a sense of depth. It flowers repeatedly from mid-spring until mid-autumn, producing flowers in bluish, light blue or purplish shades depending on the variety. Suitable for a range of sun exposures, it is easy to care for.

Variety description

Compact, deep blue in colour. Suitable for packs and pots of 8–10. It is one of the very few blue, repeat-flowering varieties for landscaping with a low growth habit. It is an undemanding plant to grow, both in the greenhouse and in the garden, and also copes well with cold greenhouse conditions.

Curiosities and special features

The name Agerato comes from the Greek 'ageratos' meaning without old age in relation to the prolonged flowering.

Origin and distribution

Native to Mexico, Guatemala and the Antilles, it was discovered in the early 18th century by the Scottish botanist and physician W. Houston, in whose honour it is named; it was subsequently introduced to Europe as an ornamental plant. There are currently various cultivars, which differ in the colour of their flowers and the height they reach.

Flower size

On its own, the flower is considered to be of average size when compared with other varieties.

Leaf

Leaf has obovate lamina covered with fine hairs i.e. slightly tomentose.

Flowering period

The floweringperiod lastsfrom mid-spring to mid-autumn for between 150 and 180 days, allowing us to enjoy its blooms for almost three seasons, often combined with other ornamental species.

Inflorescence

A corymb inflorescence bearing several flowers, creating a pleasing overall impression of lightness.

Leaf colour

A solid colour that contrasts well with the colour of the flowers.

Plant height

The plant grows to a height of between 0.1 and 0.2 m, making it suitable for compact, colourful ornamental displays, either combined with flowers of varying heights or positioned in front of more vigorous plants in a border.

Lifespan

It is often grown as an annual plant because, depending on the prevailing climatic conditions, it may not survive for long once the temperatures drop.

Where to plant

It is very well suited to adorn highly decorative green spaces such as flower beds, borders

Stem

The stem isherbaceous; the plant has no thorns.

Flower

The flower is pom-pom-shaped, medium-sized, with a funnel-shaped corolla and solid-coloured petals. It grows in small to medium-sized corymb inflorescences. It flowers from mid-spring to mid-autumn, with a flowering period of between 150 and 180 days.

Growth

Agerato has a compact growth habit, making it ideal for use in landscape beds.

Plant habit

Plant habit is globular and low.

Branching

The plant is profusely branched, giving it a pleasing decorative appearance, with patches of colourful flowers set amongst dense, lush foliage.

PH

The optimum soil pH is generally slightly acidic, ranging from 5.8 to 6.2.

Soil preparation

Before spring planting, the soil must be properly prepared; to this end, it is advisable to dig to a depth of 20–30 cm, removing any weeds, residues from previous crops and large stones, followed by working in organic or chemical fertiliser to provide the nutrients needed during the early stages of growth, and breaking up any compacted clods using a hoe. To improve drainage of excess water, create a raised bed by gently mounding the soil; finally, spread a layer of professional-grade growing medium approximately 5–10 cm thick over the surface and level it carefully.

Read more on the Joyflo blog

Sun exposure

For agerato, exposures such as half-shade, light shade and full sun exposure are optimal environmental conditions for balanced vegetative development and abundant flowering.

Ideal climate and temperature

The biological temperature ranges from 10 to 32 °C. The ideal temperature is between 16 and 20 °C, which are the most common conditions in spring; it also adapts well to hot summer climates.

Use

Due to its habit and prolonged flowering with distinctive colours, it is widely used as a plant in:

Ornamental settings

Hardiness

A variety of moderate hardiness.

Soil

Amended, well-draining soil is preferred; for pots or planters, use a spring planting medium containing peat and perlite.

Difficulty

Cultivation and maintenance are straightforward, adding value to the variety.

Growing tips

The following cultivation practices will help to ensure that the plants develop optimally:

Avoid over-watering Expose the plant to as much light as possible

It is therefore important to manage watering correctly – ensuring it is not excessive – and to provide adequate exposure to sunlight.

Combinations with other plants

It is possible to create overall effects in flowerbeds that are proportionate and balanced, both in terms of form and colour, by combining ageratum with other ornamental plants such as Lobularia maritima.

Planting

For planting in flowerbeds, an average density of22 plants per square metre is recommended in order to achieve a balanced final composition, whilst allowing each individual plant to grow to its full potential.

Propagation

Propagation can take place either by seed or by cuttings.

Watering

Use rainwater or, alternatively, tap water, either manually or via an irrigation system. When transplanting, it is advisable to support the seedling until its root system has established itself in the new planting site, keeping the soil at a constant moisture level without allowing water to become waterlogged; thereafter, allow the soil to dry out slightly between waterings to prevent both drying out and waterlogging.

Read more on the Joyflo blog

Fertilising

During pre-transplant soil preparation, carry out background fertilisation by burying slow-release organic or chemical fertiliser. Later, during the spring/summer period, apply a balanced fertiliser for ornamental species to the soil or medium to be distributed liquid, i.e. diluted in the irrigation water, or slow release granular fertiliser. Do not exceed the doses and frequencies as agerato has low nutrient requirements.

Read more on the Joyflo blog

Pet safety

It may be toxic to pets as it contains coumarin.

Edibility for humans

The flowers of some varieties are edible and are used in salads, yoghurt, ice cream and baked goods such as pastries, as well as to flavour soups and meat dishes; however, there are varieties that can be toxic if ingested.

Toxicity for humans

Some varieties contain alkaloids that are toxic to humans as well. Avoid ingestion.

Tip

Take care with the first few waterings, which should be moderate, as the ageratum is fairly susceptible to root rot. The ideal location is in partially shaded flowerbeds, preferably near the canopy of a tree that provides shelter during the hottest part of the day.