How Does the Common Ragweed Reproduce?

Seed Production

• Each common ragweed plant that grows through the entire season produces anywhere between 32,000 to 62,000 seed, cites the Purdue Cooperative Extension website. The plants that begin to grow from the middle of April through May tend to produce three times the amount of seed over the plants that start growth between middle and late June. Each seed measures 0.13 inch long and is covered with a light brown, top-shaped, woody casing.

Germination

• Common ragweed seeds require a period of dormancy prior to germination. The dormancy period lasts from late fall through winter, and seeds start to germinate during late April and May as temperatures start to get warm. Seed germination is significantly reduced in very hot weather. Seeds that fail to germinate in hot weather retreat into a dormancy state and usually germinate the next year.

Conditions Favoring Germination

• Seeds do not require deep planting to germinate effectively. Most seeds germinate very close to the soil surface and from depths of about 2 inches. Seeds that are buried very deep often fail to germinate at all. Successful rates of germination are dependent upon an optimal combination of light and temperature, according to the Purdue Cooperative Extension website. The plants thrive in no-till areas, disturbed sites and poorly fertile soil.

Plant Description

• Common ragweed grows to a mature height of about 1 to 4 feet and has simple, 4-inch long, light green foliage that is alternate above and opposite below. The leaves are divided into numerous narrow, toothed segments. The male flower clusters are 1 to 6 inches long and grow near the top of plants. The stalkless female flowers clusters grow at leaf axils. Flowers bloom in August and September.