What Is Rosinweed: Should You Grow Rosinweed In Gardens

What Is Rosinweed: Should You Grow Rosinweed In Gardens

By: Mary H. Dyer, Credentialed Garden Writer

What is rosinweed? A sunflower-like wildflower, rosinweed (Silphium integrifolium) is named for the sticky sap that oozes from cut or broken stems. This cheery plant is a member of the Asteraceae family, along with daisies, mums, sunflowers, marigolds and dandelions. Growing rosinweed plants couldn’t be easier. Read on to learn about growing rosinweed in gardens.

Is Rosinweed a Weed?

Rosinweed is an aggressive plant that spreads by seed, and to a lesser degree, by underground rhizomes. The plant shouldn’t be planted with smaller, less vibrant plants, but will do well where it has room to spread, such as a wildflower garden, prairie, meadow, or other area where it can naturalize freely.

Rosinweed Plant Information

Native to much of North America, rosinweed is hardy and drought tolerant, thanks to its long, sturdy root that taps into moisture deep in the soil.

Look for bright yellow flowers to appear from mid-summer to fall. Rosinweed in gardens attracts a number of beneficial pollinators and is also appreciated by birds and butterflies. Although rosinweed may reach heights of 6 feet (2 m.), growth usually tops out at 2 to 3 feet (1 m.).

Growing Rosinweed Plants

Rosinweed thrives in average, well-drained soil but tolerates difficult conditions, including sand, gravel and clay. Although partial shade is acceptable, you’ll see more blooms when the plant is exposed to full sunlight.

Be patient when growing rosinweed plants from seed, as it may take time for the plants to fully establish, but once established, plants grow quickly. Thanks to its sturdy stems, rosinweed rarely flops over and seldom needs support.

Tips on Rosinweed Care

Water rosinweed regularly until roots are established. Thereafter, the plant requires little moisture.

Don’t bother with fertilizer unless your soil is very poor or growth is slow. If this is the case, apply a light dose of a balanced fertilizer in spring.

Once rosinweed is established, it’s best to leave it undisturbed. Plants with long taproots usually don’t tolerate division.

Rosinweed is rarely bothered by pests or disease.

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Silphium Species, Starry Rosinweed

Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Silphium (SIL-phee-um) (Info)
Species: asteriscus (ass-ter-IS-kus) (Info)
Synonym:Silphium gatesii
Synonym:Silphium laevigatum
Synonym:Silphium scaberrimum


Water Requirements:

Drought-tolerant suitable for xeriscaping

Average Water Needs Water regularly do not overwater

Sun Exposure:


Foliage Color:




USDA Zone 7a: to -17.7 °C (0 °F)

USDA Zone 7b: to -14.9 °C (5 °F)

USDA Zone 8a: to -12.2 °C (10 °F)

USDA Zone 8b: to -9.4 °C (15 °F)

USDA Zone 9a: to -6.6 °C (20 °F)

USDA Zone 9b: to -3.8 °C (25 °F)

USDA Zone 10a: to -1.1 °C (30 °F)

USDA Zone 10b: to 1.7 °C (35 °F)

Where to Grow:


Bloom Color:

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Bloom Size:

Bloom Time:

Other details:

Soil pH requirements:

Patent Information:

Propagation Methods:

From seed sow indoors before last frost

Seed Collecting:


This plant is said to grow outdoors in the following regions:

Gardeners' Notes:

On Sep 19, 2013, kbjanet2003 from mid-Michigan, MI wrote:

I grew this plant easily from some seed given to me. I do not know how old the seed was. I sowed it in spring indoors and by August I had 4 to 5 foot plants. Easy to germinate and grow. Since I am in zone 5 I am not sure it will be winter hardy.

On Jun 25, 2013, GGT51 from Crystal River, FL wrote:

One day the plant was beautiful and full of blooms and about 4' tall. The next day it was dying. Anyone know what could cause this? I pulled up the plant and didn't see anything wrong with the roots.

Looking to Grow a Garden This Spring? Here Are Some Tips to Get Started

Consider this your gardening checklist.

Gulf Frittillary on a Liatris flower. Plant now for fall flowers.

Are you looking to start a garden this spring? Thanks to Florida's beautiful weather, there are a variety of flowers and vegetables you can grow that will flourish at this time of year. (Plus, being outside has proven health benefits, too.)

Here are some tips from University of Florida's IFAS extension site in Sarasota County on what to do—or not do—when you're plotting out your garden.

What are the best flowers to grow?

Perennials are plants that last two seasons or more. These include Florida-friendly pentas, azaleas, jasmine and gaillardia, which are in full bloom during the months of March and April. They can withstand direct sunlight, except for azaleas, which are usually found growing under the shade of an oak tree in acidic soil.

Annuals-or those that need to be replanted seasonally, include sunflowers of all sizes, zinnias and celosia. Some other plants you might find blooming in our area are gaillardia (or blanket flowers), beach sunflowers and salvias. Porter weeds, rosinweed and milkweeds like Asclepias tuberosa are native, low growing plants that attract beautiful butterflies this time of year.

Which of these plants are easiest to keep alive?

"Most of these plants are easy to keep alive when you water the proper amount and allow the plant to get established in rich soil," says UF/IFAS Florida-Friendly Landscaping Program Specialist Wilma Holley. If you don't have a green thumb, you can check out IFAS' guide to Florida-friendly plants to see which appeal to you and which grow best.

How much should you water flowers?

"A general rule of thumb for rainy season, which begins in late May/early June, is 3/4-inch of water per week, depending on rain," says Holley. "If the rain provides a half-inch or more of water, do not turn on your irrigation system that week, or add additional water." For the plant to establish in the soil, flowers need water every day or every other day. Once established they may need water once a week. More information on rainfall and irrigation can be found here.

What about potted plants?

"If plants have the tendency to be invasive or aggressive with their root systems, it is best to keep them in pots," says Bostick. "Mint is a great potted herb to grow, and produces beautiful flowers." Plants will flourish in pots if they have enough sunlight and space to grow their root system.

What conditions should the soil be in?

Soil in Sarasota is sandy, which means it doesn't hold nutrients or water well. You'll need to add organic matter to enrich the soil, such as a compost or mulch, which keeps weeds down and soil from overheating. Edible plants will need even more organic matter, especially if grown in a raised bed, as soil dries out fast and needs extra nutrients.

What about growing vegetables? Which are in bloom right now?

"Mangoes and avocados are blooming, as well as citrus," says community and school gardens coordinator Mindy Hanak. Other vegetables that you'll see in gardens right now are broccoli, cauliflower and cabbage, but as soon as the summer temps rise, they won't do well. Vegetables that survive in the Florida heat include okra, peppers, tomatoes and sweet potatoes, most of which won't bloom until summer if you plant them now. "We are getting toward the end of vegetable season as far as edibles go, so if you are going to plant something, plant it now, or wait until next Fall."

Other plants that do well in heat are Seminole pumpkins, lemongrass and eggplant, if you plant them now. IFAS has an edible gardening online series which provides more information.

Which are the quickest and easiest vegetables to grow?

"Sweet potatoes, tomatillos, peppers and eggplants are also easy to grow right now," says Bostick. "They are low maintenance, have high insect resistance and come in many varieties."

Bush beans germinate really fast, as do radishes and lettuce. "Radishes are ready to harvest is 21-29 days after planting, however, they do not like hot weather, so if you want them, grow them now," says Bostick. "Lettuce from seedlings to a full head are ready to harvest in about one month, and sweet potatoes take about 80-100 days."

Where should your vegetable garden be located? What supplies do you need?

Edible plants needs at least six hours of sunlight per day, so plant your garden in a sunny spot—the brighter, the better.

"If you are starting a garden for the first time, I recommend finding a Florida-specific gardening book," says Bostick. "This will be an easy-to-follow guide." In terms of other supplies, IFAS recommend hand tools for smaller scale gardens, a regional reference book of good and bad insects, a hand lens, or magnifying glass to search for small pests, and gardening gloves.

"It's all about 'right plant, right place and right season,'" says Hanak. "Sometimes people bite off more than they can chew, so stick with plants that thrive here in spring."

How do you know when vegetables are ready for harvest? How often should you be checking them?

Knowing when to pick certain vegetables can be a matter of determining its firmness, color and size. Always do your research about each vegetable and what it looks like when ripe. If you leave plants for too long, pests can infest your garden and bring unwanted diseases. UF/IFAS Chemicals in the Environment Agent Carol Wyatt-Evens says that if a plant is left in the garden, starts to decline and is not being taken care of, the plant will draw in pest insects that can transmit disease. If this happens, pull the plant and throw it away instead of composting it, so the infestation doesn't spread to other plants.

"Check on your plants once a week, and then twice a week as the rainy and warmer season begins," says Wyatt-Evens. "Pests like aphids can populate from a single bug to 20,000 in a matter of three weeks, and they love nitrogen-rich plants, so keep an eye out for them."

You will know when a plant is doing well if you lightly tug on its base and the roots stay firmly in place. Edible plants must be watered frequently when first transferred to the soil, and should not be planted too deep. Once the roots take hold, they can be watered slightly less frequently.

How can you keep pests away naturally?

"There is a difference between pests and natural enemies in Florida," says Wyatt-Evens. "Natural enemies eat the pests, so are necessary for a garden's health." Natural enemies commonly found in Florida include lacewing larvae, lady beetle adults and larvae and praying mantids. If further control is needed for the pest insects, use biorational pesticides, horticultural oils, insecticidal soaps or microbials as spot treatments, and as needed. Always follow the product label instructions.

For more information, call (941) 861-5000, or email [email protected] for gardening help.

Tag Archives: rosinweed

2015 seems to be the year of the genus Silphium in the arboretum. In recent years, I can’t remember them looking so bright or growing so tall. With the spring and summer rains these sun-loving, yellow-flowered plants have reached a new level. In fact, they are among the tallest plants of the prairie in late summer and autumn. We grow and sell four species: Prairie Dock, Silphium terebinthinaceum Cup Plant, Silphium perfoliatum, Compass Plant, Silphium laciniatum and Rosinweed, Silphium integrifolium. Each of these are distinct and easily identified by their unique leaves.

Prairie Dock (Silphium terebinthinaceum)

I call this the Hosta of the prairie. It almost has a tropical-look to it, with large rough leaves up to one foot wide and two foot long. It will make a statement in the landscape, but give it plenty of room and keep it away from walkways, because the long stems tend to arch over the path. Individual clumps can become large over time reaching six feet in diameter. The yellow flowers develop in mid-August atop tall leafless stalks. This member of the tallgrass prairie is one of my favorite wildflowers. In my opinion, Prairie Dock is a must in your wildflower garden.

Prairie Dock with Missouri Black-eyed Susan

Cup Plant (Silphium perfoliatum)

A natural bird bath in the landscape. Each pair of leaves clasps around the stem forming a small basin. When it rains, these crude cups fill with water that is then available to wildlife. They stand tall in the landscape and therefore work well as a screen. I have also used them as a dark green background for other shorter perennials like black-eyed Susan, and gayfeather. The yellow blossoms can be seen starting in July and are visited by a host of butterflies. Later, birds cherish the seeds. Cup Plant thrives in heavier clay soils or even wet conditions. It will be happy in any setting if given ample sunlight.

Compass Plant (Silphium laciniatum)

Do you need directions? This is the plant that can help. The interesting basal leaves look like flat hands. Those lower leaves usually orient themselves north-south to minimize exposure to the intense summer sun, hence the descriptive common name. These extremely tall (up to ten feet) wildflowers are found in prairies and glades throughout the eastern third of Kansas. Each stem is covered with tiny white hairs that give it a rough, bristly feel. The bright yellow flowers emerge along the upper parts of the plant in summer. Split or broken stems exude a clear sticky resin much like pine sap. Native Americans used this resin as a mouth-cleansing chewing gum. I think I will stick with Trident®.

Rosinweed (Silphium integrifolium)

Rosinweed is shorter, but just as tough as the other Silphiums. Again, the name describes the resin exuded if the stem is bruised or broken. The golden yellow flowers that mature at the top of the stems are beautiful in the summer. It is a pollinator magnet, attracting bees, butterflies and even hummingbirds to the flowers. It becomes a natural bird feeder in the fall and winter as the seeds are devoured by birds. It is quite drought tolerant once established and is at home in a wide variety of soils.

While each of these wildflowers are unique in appearance, especially as you look at the leaves, they all have that “clear, sticky juice” that exudes if the stem is damaged. I love them in the landscape, but they need room because they grow so tall. They are great in prairie settings or areas on the periphery of your yard. You can’t go wrong – just give them plenty of sunlight so the sunflower-like blooms can brighten your summer landscape.

Each of these plants can be purchased at our FloraKansas Fall Plant Sale, September 11 to 13.

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