Plant profile

Wild sunflowers’ relatives

Genus Silphium

Silphium (often called rosinweed) is a group of tall, tough native wildflowers known for sunflower-like blooms and long-lasting nectar and pollen. They’re a strong choice for pollinator gardens, schoolyards, and naturalized edges where you want big plants that can handle summer heat once established.

Plant Type

Wildflowers (herbaceous perennials) > Wild sunflowers’ relatives

Aliases

Rosinweed

Native Range

Native to parts of North America

Bloom window

Mid-to-late season, depending on species

Overview Summary Impact Recognition Location Requirements Glossary Get Involved

OVERVIEW

About This Plant

Silphium (rosinweed) is a group of tall, tough native wildflowers valued for their strong stems and sunflower-like blooms. They serve as a robust vertical anchor, adding structural complexity and height to meadow-style or naturalized habitat gardens, especially in sunny spots where they thrive once established.

These plants are highly valuable to local wildlife for providing a crucial, mid-to-late season source of long-lasting nectar and pollen. This resource is vital for many native bees and emerging insects when other blooms are fading. To support foraging insects, always ensure the planting area is pesticide-free, especially during the bloom period.

Best role for pollinators

Back-of-border pollinator plantings, naturalized areas, school gardens, and sunny edges where tall, long-lived flowers are welcome

Wild sunflowers’ relatives (Silphium) — https://www.inaturalist.org/photos/154378985 Photo: no rights reserved | CC0 | iNaturalist

FAST FACTS

Quick Details

Essential stats and requirements for quick reference.

Category	Details
Also known as	Rosinweed
Bloom window	Mid-to-late season, depending on species
Typical height	Tall (often chest-high or more, depending on species and conditions)
Pollinators supported	Bees, Butterflies, Flies, Beetles
Light & moisture	Sun with average moisture; tolerates some dryness once established
Best roles for pollinators	Back-of-border pollinator plantings, naturalized areas, school gardens, and sunny edges where tall, long-lived flowers are welcome

SUMMARY

If You Remember Three Things

A quick scan of what they do, what they need, and the best first step.

What they do

Silphium flowers provide easy-to-access nectar and pollen for a wide mix of visiting insects through the warmer part of the season.

What they need

Give them sun, room to grow, and patience while roots establish.

One best action

Plant Silphium where it can stay for years—choose a sunny spot with space, then leave it alone to settle in.

IMPACT

Why Plant This?

Silphium adds reliable, mid-to-late season flowers and strong vertical structure—useful for pollinators and for making habitat gardens feel full and intentional.

The common name “rosinweed” comes from the sticky, resin-like sap some species can have.

Key Impacts

What it Supports

Big, open blooms are usable by many different pollinators.
Tall stems and long-lived clumps add structure to pollinator plantings.
Once established, many Silphium species are resilient and low-maintenance.

RECOGNITION

Identification Guide

Silphium species can vary, but they share a bold, “prairie sunflower” look and a sturdy, upright habit.

Leaves

Sturdy, often coarse leaves; shape and arrangement vary by species, but many look bold and substantial on thick stems.

Flowers

Yellow, daisy-like flower heads with a central disk; often held high on tall stems.

Fruits

Dry seed-like fruits typical of the daisy family; left standing, they can add winter texture.

LOCATION

Where It Grows

Native environments and the best spots to place it in your landscape.

Habitats

Open sunny areas
Meadow and prairie-style habitats
Sunny edges and clearings

Where it is often used

Back-of-border anchor plant
Meadow or naturalized planting
Pollinator strip along fences or sunny edges
Schoolyard habitat garden with tall “wow” factor

SEASONALITY

When It Blooms

Notes on bloom windows and how this plant helps pollinators across the seasons.

Bloom window

Silphium generally shines from mid-season into later summer, depending on the species and site.

Bloom Season Role: A sturdy mid-to-late season nectar and pollen source

Seasonal benefits

Supports a steady stream of insect visitors during warm months
Pairs well with earlier and later bloomers for season-long habitat

REQUIREMENTS

What It Needs

The right mix of sun, soil, and space for healthy growth.

Sun exposure

Best in full sun; can handle light shade but may lean or bloom less.

Soil type

Adaptable to many garden soils as long as water doesn’t sit for long periods.

Moisture needs

Water regularly during the first season; after that, water during long dry spells if plants look stressed.

Planting method

Plant in spring or fall. Give each plant plenty of space so it can form a clump without crowding neighbors.

Mulching tips

Mulch lightly to reduce weeds and hold moisture, keeping mulch off the crown.

GARDENING GUIDE

How to Grow It

Simple steps to plant, prune, and maintain healthy trees without pesticides.

Planting tips

Choose a sunny spot with room for a tall, wide clump.
Loosen the soil and remove weeds where the plant will go.
Plant at the same depth it was growing in its pot.
Water well after planting and keep soil lightly moist during establishment.
Add a thin layer of mulch to reduce weeds, leaving space around the stem.

Seasonal care

Stake only if needed in windy sites or if grown in part shade.
Deadhead for a tidier look, or leave seed heads for winter interest.
Cut stems back in late fall or early spring.
Divide only if the clump becomes crowded (many Silphium prefer to be left alone).

What not to do

Planting it where it blocks a walkway or shades smaller plants.
Giving up because it doesn’t look impressive the first year.
Using pesticides to deal with leaf damage or insects.
Overwatering an established plant.

Pairings

Best Pairings for Season-Long Bloom

Pairing ideas to keep pollinators fed throughout the growing season.

Early Bloom

Golden alexanders
Wild geranium
Penstemons

Mid-Season Bloom

Bee balm
Purple coneflower
Blazing star

Late-Season Bloom

Asters
Goldenrods
Joe-Pye weed

Silphium is a genus, not a single plant—different species can vary in height, leaf shape, and bloom timing. If you’re shopping, look for a species that fits your space and the look you want.

GLOSSARY