As the weather turns colder in some parts of the world, signs of autumn begin to appear. The leaves of some trees turn bright shades of red, yellow, and orange.

At this time of the year depending on your location, you may also see a familiar flower: chrysanthemums. We often call them "mums," for short.

In parts of the United States, many people use chrysanthemums as decorations. The flowers sit next to pumpkins for Halloween, October's famous holiday. But then the mums are thrown away along with rotting jack o' lanterns.

This yearly tradition bothered plant expert Jessica Damiano. In a recent article for the Associated Press, she wanted to know why people simply threw away their mums. So, she asked some of her neighbors in Long Island, New York.

Everyone had the same answer: They thought the flowers were annuals -- flowers that only last for one season.

Damiano explained that there are annual and perennial mums. Perennials come back for several growing seasons. Garden chrysanthemums, she adds, are actually perennials. Annual chrysanthemums are often sold in stores as potted gift plants. Special plant stores usually sell perennial mums.

If the plants are not labeled at a store, Damiano said to look at the leaves. The large, flat leaves of perennial mums have deep cuts around the edges. The narrow leaves of annuals do not.

Perennial mums are hardy flowers. But they cannot survive freezing temperatures. They also cannot survive extreme summer heat. So, that means about half of the United States is good for growing mums.

Perennial chrysanthemums, Damiano said, come from China. Kaifeng, a city in China's Henan province, is famous for its mums. Each year, the city holds a popular festival to celebrate the flowers. Chrysanthemum festivals are also held in other countries -- like Pakistan, Germany, South Korea, Japan, and the United States, to name a few.

Chrysanthemums come in shades of orange, red, rust, pink, purple, yellow, cream, and white. Some can grow to nearly one meter in height. They reach their mature size in about three years. In warmer climates, they bloom again in spring.

Planting tips

Here are some chrysanthemum planting tips.

Plant mums in well-draining soil. And plant them as early in the season as possible. Spring is the best time -- if you can find them at plant stores. In the United States, that can be difficult.

Damiano said she has done well with fall plantings. But that might not work if temperatures drop below freezing within six to eight weeks of planting. So, she added, there is a risk.

Adding compost to the soil improves drainage. It is also a good idea to set the plant into the ground at the same depth as it was growing in its container.

Make sure there is enough space between plants to prevent crowding. Planting the mums too close together can lead to mold, mildew, and fungal diseases. If plants become overgrown, separate them in spring after new growth appears.

Mums grow best in full sun with moist soil. So, do not let the soil dry out. It is also a good idea to fertilize them regularly. The flowers are heavy feeders.

Put mulch around the plants to help keep up the soil moisture and keep out unwanted plants. Add more mulch after the ground has frozen. This protects roots from freezing then warming then freezing again.

When plants stop growing, leave them in the garden over the winter. The above-ground plant matter, although dry, will help to further protect roots. Cut back the dry plant matter in spring after new growth emerges.

Starting in their third year, cut back one-third of the plants' growth three times per season: at the beginning and middle of June and again during the first week of July. Do not worry if you remove small flower buds. This will lead to more blooms and create fuller, bushier plants.

If chrysanthemums are not hardy in your zone, you can still enjoy them.

Potted mums do not do well in the heat. So, do not buy them in late summer. They will survive better and longer if you wait until temperatures cool.

With potted mums, move them inside overnight if temperatures drop to freezing. Water thoroughly when the soil dries out. But again, do not let the plants stay dry for too long. The plants should remain alive until spring, when you can bring them back outdoors.

Do the same in warmer climates. Damiano warns that when spring or summer temperatures get too hot – between 27 and 31 degrees Celsius -- bring the plants indoors. Do not bring them outdoors again until things cool down in autumn.

I'm Anna Matteo.

And I'm Andrew Smith.

Jessica Damiano writes regular gardening columns for The Associated Press. Anna Matteo adapted this for VOA Learning English.

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shade – n. the darkness or lightness of a color

decoration – n. something that decorates or beautifies

jack o' lantern – n. a lantern made of a pumpkin usually cut to resemble a human face

garden – n. a plot of ground where herbs, fruits, flowers, or vegetables are grown

label – v. a slip (as of paper or cloth) that is attached to something to identify or describe it : to name or describe with or as if with a label

hardy – adj. able to survive unfavorable conditions (as of weather)

bloom – n. the flowering state

compost – n. a mixture largely of decayed matter of once living things (as grass) or their products (as coffee grinds) and used for fertilizing and conditioning land

moist – adj. slightly or moderately wet

mulch – n. a covering (as of straw or sawdust) spread over the ground to protect the roots of plants from heat, cold, or evaporation, prevent soil loss, control weeds, enrich the soil, or keep fruit (as strawberries) clean