Species giant hogweed
Giant Hogweed (Heracleum mantegazzianum) showcasing white flower clusters with lobed green leaves

giant hogweed

Heracleum mantegazzianum

Giant hogweed (Heracleum mantegazzianum) is an invasive plant species native to the Caucasus region. It can grow up to 5 m tall, with hollow stems 2-4 cm in diameter and white flower heads up to 80 cm in diameter. The plant sap can cause irritation and even blindness when it comes into contact with skin. It is important to control infestations of this plant as it can be quite damaging to ecological systems, particularly if it crowds out native species.

Cycle:

Herbaceous Perennial

Watering:

Average

Propagation:

Seed Propagation,Cutting,Layering Propagation,Division,Grafting Propagation

Hardiness Zone:

3 - 9

Flowers:

White Flowers

Sun:

Full sun,part shade

Soil:

Well-drained

Fruits:

Fruits In Summer Ready In Fall

Leaf:

Yes

Leaf Color:

green,yellow,purple,white

Growth Rate:

High

Maintenance:

Moderate

Poisonous To Humans:

Yes

Poisonous To Pets:

Yes

Salt Tolerant:

Yes

Thorny:

Yes

Invasive:

Yes

Care Level:

High

watering

Watering giant hogweed once or twice a week is ideal. Depending on the season and weather, you’ll need to adjust your watering schedule accordingly. During hot, dry summers, you may need to water your giant hogweed every 2 to 3 days, while more moderate temperatures and humidity levels may only require 1 to 2 waterings per week. When watering, be sure to soak the soil and provide a deep watering that extends several inches below the surface. Aim to provide about 1 to 1.5 inches of water per week to ensure good growth and flowering.

sunlight

Giant hogweed is an invasive species of plant, and it requires plenty of sunshine in order to thrive. The plant need at least 6 hours of direct sunlight per day, and ideally more. The best time to give it this sunlight is during the morning hours, between 8 am and 10 am, when the sun is at its brightest and most direct. Even if the sky is partly sunny during this time, giant hogweed will still benefit from a few hours of direct sunlight. Morning sunlight also helps the plant produce sugars, which it needs for energy and growth. After 10 am, the sunlight should be filtered or diffused to avoid burning or bleaching the leaves of the plant.

pruning

Giant hogweed (Heracleum mantegazzianum) should be pruned when the plant has grown to around 4-5 feet tall. Pruning should occur in late winter or early spring, before the plant has begun to send up its flowers. Prune the plant back by a third or half its height to maintain its size, shape, and structure. It’s very important to wear protective clothing while pruning as contact with the leaves and sap of giant hogweed can cause skin irritation and burns.

Season

Fall
Winter
Spring
Summer
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Starts Flowering

Giant hogweed typically starts flowering in June or July.

Harvest Fruit

The harvesting of Heracleum mantegazzianum typically begins in July and August.

Hardiness Map