How to plant Ageratum Houstonianum, Growing from Seeds

Ageratum (whiteweed in the USA) is a flowering decorative plant that will become a beautiful decoration for your garden. It belongs to the family Asteraceae and the genus Ageratum. Despite there are 60 species of the Ageratum, only the Ageratum Houstonianum is cultivated.

The homeland of the Ageratum is South and Central America. Also the flower is found in India and in countries with a warm tropical and subtropical climate. The In the wild nature, Ageratum is a perennial and it is an annual when grows indoor.

Ageratum is known for more than 200 years, but is actively grown only recently.

Care for Ageratum Houstonianum is easy because it is an unpretentious plant. The plant grows in a warm climate outdoor but it does not tolerate frost. If you like this flower, you can grow an Ageratum perennial in greenhouses.


You can see these beautiful flowers in different compositions, for decorating living curbs and flower beds. The garden with Ageratum Houstonianum always attracts the attention of passersby its rich color palette.

This plant looks like a flowering carpet and has a long flowering period wich continue from May to the first frost.

In translation from the Latin (ageratos) - ageless and this has proof.

  • The long flowering period.
  • Flowers do not fade for a long time after cutting.

Choose for the plant a well-lit place. But you have to remember than this flower is very sensitive so intense direct sunlight can damage its. Also the Ageratum grows well in the penumbra.

An annual plant reproduces by seeds, but only a small part of them inherits maternal similarity.

Perennials are propagated by cuttings.

Description of the Ageratum Houstonianum

Ageratum Houstonianum is a low-growing plant which can reaches up to 0.5 m in height and has multi-colored flowering. The flowers are blue, purple, lilac and cream colors. Most often you can see the blue flowers of various hues in gardens and parks.

Description of the Ageratum

There are two types of shrubs:

  • Straight
  • Sprawling

There are also dwarf species which have adapted to exist indoors.

The plant has fluffy bisexual flowers which collected in a dense inflorescence. The flowers are small of 1 - 1.5 cm in a diameter and they grow very tightly to each other that create a floral fluffy carpet.

Seeds are collected in autumn. There are several thousand from one achene.

The bush has numerous pubescent stems. Adjacent roots grow in branching varieties when shoots come into contact with the soil.

The leaves of the Ageratum Houstonianum are oval, triangular or diamond-shaped and grow on short petioles. Leaves are green monochromatic color and have burrs.

The leaves are located alternately in the upper part of the bush and in the lower part opposite. Shoots are upright up to 60 cm in height.

Small flowers collected in the inflorescence - baskets. Baskets collected in a complex thyroid inflorescence up to 10 cm in length.

Stigmas of flowers and perianth are painted in a bright, uniform color. A strong pleasant aroma is felt during the flowering period.

Fruitages begin to ripen in late August when the baskets fade. Fruitage is small achenes of dark color. The size of the fruit is 3-4 mm long and 0.5 mm wide. There are several thousand seeds in the middle of the fruit. The seeds are wedge shaped and pentagonal and have the ability to germinate 4 years.

Perennial varieties of Ageratum are propagated by cuttings.

Ageratum - how to grow of seeds, when planted outside

Growing of the Ageratum. In the beginning it is necessary to sow seeds, then to sprout seedlings. Only then the flower is planted on the street.

How to sow seeds

Seed for seeding is collected from the main shoot and the first level children.

When is it necessary to sow an Ageratum for seedlings?

Seeds are planted on the soil surface from mid-March to mid-April. Small containers are used for sowing. The soil is used from a mixture of peat, sand and humus. All components are taken in the same ratio.

Substrate is abundantly moistened from the atomizer and seed is sown onto the surface. Seeds are distributed evenly on the surface of the soil and sprinkled from above with a 2-3 mm layer of soil.

The container is covered with a polyethylene film (glass jar) or placed in a mini greenhouse. You need to make greenhouse conditions for the seeds. The temperature should be kept at 20-22 degrees.

The container with seeds is placed in a well-lit place and protected from direct sunlight. Pot with seeds regularly is aired and the moisture of the soil is monitored. If it is necessary the soil is slightly moistened from the sprayer.

The first shoots will appear after 1-2 weeks. Young shoots are transplanted into separate containers when the first 2 leaves appear. By this time, the shoots will be stronger and will not need a greenhouse.

The second time each seedling is transplanted into separate pots. Ageratum is transplanted to outdoors when the air temperature at night is above 0 degrees. As a rule, plants are transplanted in the middle of May in a temperate climate.

Ageratum Houstonianum: how to plant outside

How to plant Ageratum outside

Young sprouts have to become hardy before planting. This procedure has to be done up to 3 weeks. The temperature is gradually reduced up to 15 -17 degrees indoors and plants are placed outdoors during the daytime every day. You should protect young plants from rain and direct sun rays.

The first flowering will appear 2 months after sowing the seeds. Flowers are planted along the flower beds and paths to create curbs. The seedlings are planted at a distance of 15-20 cm to create a dense color coating. The seedlings are watered and carefully extracted from the container before planting.

Small holes are made in the ground where each germ is placed. The hole is sprinkled with soil and watered abundantly.

Composition of soil for Ageratum (main components): peat and leaf earth.

Ageratum planting outside

The basic requirements:

  • fertile and loose soil
  • it must pass well water and air
  • neutral acidity

Clay and heavy soils do not suit for Ageratum.

Place for planting has to be well lit. The adult plant is not afraid of direct sun rays and Ageratum less intense blooms in the penumbra. The first buds will appear a month later after planting outside.

How to Care for Ageratum outside

Care of the plant is easy and suitable for beginning gardeners.

The soil is mulched before planting. For mulching is used of sawdust or manure.

The soil is regularly loosened. Weeds are removed when they appear.

Ageratum is watered moderately when there is no rain. The top layer of the soil should dry before each watering. Roots of plant will rot, if it watered excessively. The flower will grow better in dry than in boggy soil.

Fertilizers are used several times during the season.

  • First time 2 weeks after disembarkation.
  • The second time during the appearance of buds.
  • The third time in the flowering period (at the discretion of the horticulturist)

Organic fertilizers alternate with mineral fertilizers.

Complex mineral fertilizers are added when the flowering is shallow. The Ageratum is watered with dilute manure once per season. Fresh manure or nitrogen fertilizer accelerates the growth of leaves but reduces flowering.

Wilted buds and dry shoots are cut off on a bush. The bush will grow even better after pruning. But you must leave several branch points (internodes).

Use potassium-phosphorus fertilizers for abundant flowering.

Beautiful flower of Ageratum

Rules for successful flowering:

  • Fertilizers on a nitrogen basis should be used in small quantities.
  • The soil must be nutritious and loose.
  • The Ageratum needs good lighting without drafts.
  • Regularly do trimming of the bush.

Flowers blossom not simultaneously, so they decorate the bush with their flowering during all summer. Wilted flowers should be removed, if you do not collect the fetus for re-sowing for the next year.

Care for the Ageratum after flowering

Blue Ageratum

Flowering ends with the first frosts at night, as the plant is unable to tolerate frost. Ageratum should be propagated after flowering.

There are two ways to propagate the bush.

Fruits are dried and seeds are harvested from them. As a rule, the seeds are harvested from the main and daughter shoots. Seeds retain ability of germination for 3-4 years. They are stored in a dry place in paper bags. In the spring, seeds are planted to grow seedlings.

The second way

Using the second method, you can prolong the flowering and then propagate the bush with cuttings.

With the onset of the first frost, still flowering plants are dug and transferred to the indoors. Ageratum hibernates inside, but you need to move it indoors gradually. For example the first few days the flower is placed on the terrace and the temperature of the external environment is gradually increased.

As a rule, the plant will not bloom inside due to lack of sufficient lighting, but blooming plants will bloom for a long time.

Gardener sometimes can prolonging flowering until the New Year.

Ageratum after flowering

It is recommended to keep the flower at a temperature of 7-15 degrees during the winter. The bush is cut on cuttings in spring. The place of the cut is made oblique to increase the area to absorb moisture and nutrients from the ground.

Gardener sometimes can prolonging flowering until the New Year. It is recommended to keep the flower at a temperature of 7-15 degrees during the winter. The bush is cut on cuttings in spring. The place of the cut is made oblique to increase the area to absorb moisture and nutrients from the ground.

Cuttings are processed with a growth stimulant and are planted in small containers with soil. The container is covered with a film or placed in a greenhouse. The soil is constantly kept moist and the temperature in the greenhouse should be 20-22 degrees.

Cuttings will have their own roots after 2 weeks and young shoots will begin to grow after planting in the soil after a month. Cuttings are transplanted outside when night temperature is above 0 degrees. The places for planting are chosen well-lit.

Growing cuttings, unlike seed reproduction, increases the health of the Ageratum.

Also you can plant a bush entirely outdoors, if you do not want to cut it. Ageratum is a perennial plant and you can also transplant it during several years and without cutting.

Pests and diseases of Ageratum

The plant that grows outdoors is often attacked by pests and various diseases.

Root rot often affects the Ageratum. The main reason is frequent rainfall or over-watering. Beforehand, you need to prepare a place for planting. A layer of expanded clay (drainage) is laid to drain excess moisture.

The plant is exposed to diseases: cucumber mosaic virus, bacterial wilt, nematodes and owlet moths (Noctuidae).

The plant is thrown out when root rot is detected. Signs of defeat: the Ageratum gradually fades, leaves and inflorescence are fallen. But you can prevent the appearance of rot.

To do this you need:

  • The ground must be airy and sandy
  • Drainage system, if it is necessary
  • Watering moderate and controlled
  • Weeds are periodically removed and the soil is loosened

If Ageratum has undergone root rot, the damaged plants must be excavated and healthy ones treated with a special preparation.

Also, the appearance of the cucumber mosaic virus is fatal for an Ageratum.

The main signs of the virus: yellow spots appear on leaves that gradually increase. The bush also needs to be dug out and thrown away.

Seedlings or bushes indoors need to be protected from whitefly and spider mites. The surface is treated with a soap solution or a preparation.

  • Spider mite - a white coating on the leaves in the form of a spider web. The surface of the leaf is covered with white spots.
  • Whitefly - a white coating on shoots and leaves. It is a tiny white moth that drinks juice from a plant. If you do not notice the pests on time and do not take measures, the plant will gradually lose its vitality and wither. Use insecticides against them.

Using Ageratum in landscape design

Ageratum in landscape design

Ageratum is a universal plant for creating flower compositions. You can buy mixed seeds of several varieties with different colors of flowers. In the end result you will get multi-colored paths and curbs created from flowers.

The plant is used in the composition to create alpine hills and flower beds. High varieties of Ageratum are used as hedges. They are used to create colorful tracks and carpets. For example the blue varieties of Ageratum create an imitation of a stream which flows in the wind.

Ageratum is used in the composition with Calendula, Phlox, Salvia, Lion's pharynx, etc.

Low-growth Ageratum is used for decorating arbors. It is planted in pots in ornamental flowerpot on balconies, loggias, around arbors and verandas.

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