Pale-leaf Sunflower – An Aggressive Native Plant

Pale-Leaf Sunflower is a showy perennial native to North America. Scientifically known as Helianthus strumosus, it typically grows 3-6′ tall in full sun and well-draining soil. Blooming numerous 3-4″ diameter yellow flowers in late Summer, it attracts numerous bees and butterflies. Excellent for wild areas, it is a colonizer via it’s rhizome roots.^[1][2]

Often encountered along roadsides and forest edges where it blends among other heat loving plants like Bergamot and Black Eyed Susan, colonies of this flower really stand out. Unlike other species of perennial sunflower, this one isn’t so tall as to tower over humans, but in an open or barren area it will quickly colonize it, preventing other species from establishing themselves. This happened in my own backyard years ago! So, it might be best to plant this species in year two or three of establishing a meadow.

This was one of the first flowers I grew in my backyard Micro-prairie. And it even bloomed the first year! I was quite happy to see it begin to populate, and by year two there were a few sprouts. This quickly turned into a dense mat by year three though, so I had to work to contain it (which I did), but not without some effort. However, as I will discuss later in the article, I developed a method that worked, and wouldn’t be too much effort when first transplanting into the garden.

But, this article will be a full profile on this flower. Just scroll down or click on the buttons below to jump to a section.

Facts

• Growing up to 6′ tall, it blooms yellow daisy-like flowers for 3-6 weeks in Summer
• Producing nectar and pollen, it feeds long & short-tongued bees, butterflies, and birds eat the seed
• Pale Leaf Sunflower has a wide native range, covering roughly half the country
• A colonizer, this plant can aggressively spreading via underground rhizomes similar to Canadian Goldenrod

Native Range

The native range of Pale-leaved Sunflower covers a large swath of central and Eastern North America. The primary range is form Ontario-New Brunswick Canada, South to Louisiana and Florida

Reference Table

Scientific Name	Helianthus strumosus
Common Name(s)	Pale-leaf Sunflower, Woodland Sunflower
Native Range, USDA Zone	Eastern North America, USDA hardiness zones 3-8
Bloom Time	Summer
Bloom Duration, Color	3-6 weeks, Yellow
Height	3-6′
Spacing / Spread	1-3′
Light Requirements	Full sun to part sun
Soil Types	Sandy loam to clay loam
Moisture	Dry to medium, well-draining
Fauna Associations / Larval Hosts	Bees, butterflies / hosts Silvery Checkerspot

Pros and Cons

Pro

Beauty

The flowerheads produced by this plant are beautiful. They make a showy display in Summer, and can particularly brighten up a roadside or meadow.

Pollinators

Numerous pollinators will feed on the nectar and pollen that Pale-leaf Sunflower has to offer. And it does host the Silvery Checkerspot, similar to other members of the Helianthus genus.

Con

Aggressive

The main drawback to this plant is it’s aggressiveness. It will rapidly spread in open or recently cleared areas – it’s tiny sprouts and thick rhizome are readily identifiable in Spring. This is not a plant for a formal mulched flower bed, nor a recently cleared bed/area for a wildflower meadow.

In fact, I would only consider adding it to a thickly planted, established meadow or prairie. In this way the surrounding competition will keep it in check from completely taking over. Based on my own experience, I personally consider this to be one of the most aggressive native plants I’ve ever seen. This is mostly due to it’s rhizome spreading.

Identification and Characteristics

Stalk

The stem is generally smooth, green, round, and may lean in open areas. The plant typically is 3-6′ tall depending on available sunlight and water.

Leaf

Leaves are primarily oppositely arranged, but can be alternate (occasionally). In general have 1″ stems, lanceolate or lance-ovate shapes, 3-7″ long by 1-4″ wide at the base. Margins are often serrated. The leave has a medium to dark green color on the upper surface with pale green below^[3].

A key factor in identifying this species from similar perennial Helianthus is that it will have two prominent lateral veins near the base that arc to parallel the central vein.

Flower

A single plant may produce 3-15 flowerheads that are 3-4″ diameter. Each flowerhead will have 10-20 yellow petals (ray florets) surrounding a central disc that contains 30-50 disc florets^[3].

The blooming period is generally in late summer, from July to August, lasting from 3-6 weeks.

Root

The root system is fibrous and rhizomatous. This is probably one of the most aggressive perennial sunflowers I’ve ever grown, with a fast developing rhizome system that will expand rapidly.

Growing Conditions

Pale leaf sunflower will grow best in full sun to part-sun, in medium to dry soil. It is drought tolerant, but will not grow as tall. Along east or west facing exposures this plant may lean, as it will reach for the sun.

Problems

A fungus, Gibberidea heliopsis has been documented to attack Helianthus strumosus, particularly in the upper Midwest including Wisconsin^[4]. The primary symptom is black spots along the stem of the flower in Spring, followed by black leaf spots later on.

How to Grow Pale-leaf Sunflower from Seed

It is fairly easy to grow Pale-leaf sunflower from seed. I had no trouble doing it back in 2017, and actually got a bloom the first year. To overcome dormancy you need to cold-stratify the seed or winter sow it. Personally, I prefer winter sowing as it is just the easiest method with minimal risk of mold as opposed to cold stratifying the seed in moist paper towels in the fridge.

But the seed should be cold stratified for 30-60 days. This can be accomplished by using a moist paper towel/baggy in the fridge, or by winter sowing (my preferred method). For sowing, the planting depth should be very shallow – just barely covering the seed. Or even just on top of the soil (if winter sowing).

Direct sowing

If you wish to direct sow, simply scatter the seed on disturbed soil anytime between Fall and very early Spring. Then, walk over the area to ensure good contact. The seed should germinate in Spring as soil temperatures warm up.

Wildlife, Pests, and Diseases associated with Pale-leaf Sunflower

Pollinators

Pale-leaf sunflower will primarily attract long-tongue bees, but also short-tongue bees as well as some butterflies.^[5] It is not overly popular, but does provide both nectar and pollen. Additionally it hosts the Silvery Checkerspot caterpillar.

Deer and Rabbits

Deer and rabbits may browse the foliage of this plant when young. As it gets older, the leaves turn a bit rough and the texture may be off-putting to herbivores. Liquid fence will protect the plant when young, and in early Spring.

Disease

The primary risk to this plant is fungus (black spots on stem and leaves). In my experience, the fungus is not fatal but will just make it look bad.

Where you can buy Pale-leaf Sunflower

Pale-leaf Sunflower is typically not sold in nurseries, as it isn’t a typical ‘garden friendly’ plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map.

Where to buy seeds

We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)

Uses of Pale-leaf Sunflower

Landscaping

Due to this plant’s aggressive nature, Pale-leaf Sunflower should not be grown in mulched or formal gardens. It is best left to established meadows, open woods, prairies, and roadsides. This is absolutely one of the most aggressive plants I’ve ever grown, and was the subject of a video I made some years ago (since hidden, as my initial attempts to contain it did not work).

How to contain Pale Leaf sunflower

I have had some success containing this flower by planting it inside of a pot that was completely lined with landscape fabric. The spread has essentially been contained, as far as I can tell. But I will briefly recount my history dealing with the rhizomes of this plant.

Back in 2017/2018, when I was first constructing my backyard Microprairie I included this plant, not truly understanding what I may be getting into. This is before my YouTube channel and before I became more adept at documenting my garden, so you’ll have to forgive me for not having too many pictures.

But in it’s second year I noticed a lot of sprouts all round where the flowering stalk was the previous year. These sprouts basically made a 3′ diameter, expanding radially from the center. I should have taken this warning and investigated, but alas I got ‘busy’ as we all do. And I basically ignored it the rest of the season.

At the start of it’s 3rd year though, I could see I had a problem. Sprouts were expanding rapidly and weaving in and out of places they shouldn’t. I grabbed my potato fork and went to work. Loosening all the soil I uncovered a vast and dense network of thick rhizomes weaving every which-way around a 10-20′ area. I dug up enough to fill several gallons in a 5 gallon bucket. But, rather than just plant a few sprouts and repeat this exercise, I decided to try to plant a few sprouts inside of a pot with the bottom cut out, thinking that the rhizomes would stay in the top 2-3″ of soil. So that is what I did, with the pot walls extended 6-9″ deep. I considered the problem solved, and moved on…..

Then 2021 hit. And I was still pulling random sprouts that were connected to rhizome fragments that I had missed the previous year. This seemed to be a manageable problem. But around the pots, which were supposed to contain the spread, I noticed multiple shoots that should not have been there. So, I grabbed a spade and excavated the area only to find out that the rhizomes, once they had hit the wall of the pot turned downward. They went underneath the edge of the pot and then turned upwards, reaching for the soil surface either directed by gravity or temperature.

So, this put me at a crossroads. I had been defeated in containing this hyper-aggressive sunflower…at least for the moment. Do I just rip it out and poison any survivors? Or do I attempt to contain it again…..

Well, I decided that I would get creative. I thought what if I were to plant it within a large pot, but the roots couldn’t escape? This would work if there were no drain holes. But, that would lead to other problems (probably root rot). However, I thought that perhaps I could line the bottom and sides with landscape fabric, thinking that it would prevent the rhizomes from escaping. This method worked.

Well, it’s been several years, and this solution has worked. The few sprouts I find each year are coming from other plants that escaped my wrath in 2021. I always trace their rhizome to see their origin, and they all end at an old dead torn part of rhizome – never from the pots.

Companion Plants

Pale leaf Sunflower does well with other sun-loving flowers that are of decent size, and can tolerate medium-moist to dry soil. Some good pairings include Wild Bergamot, Spotted Beebalm, Echinacea, and some Mountain Mints. For some ornamental grasses that pair well, try Little Bluestem or Purple Top.

Medicinal Uses

Historically Native Americans used the roots of Pale Leaf Sunflower to treat worms or for respiratory problems. Infusions or decotions were made and administered^[6].

Final Thoughts

Quite possible the most aggressive native plant I’ve encountered (next to Goldenrod or Snakeroot), Pale-leaf Sunflower has it’s place in wild areas, meadows, prairies, and roadsides. It does produce numerous beautiful flowers that are beneficial to a large number of pollinators, and birds will also favor the seed like other members of the Helianthus genus.

If you have a wild border garden or meadow, this can make a great addition once the area has already been established for 2-3 years. And while I have managed to tame this flower, I would necessarily recommend someone else take the risk! But it is beautiful, and if you are in love with sunflowers, well, this can be another addition to your collection to keep those beautiful yellow Helianthus flowers showing nearly all season.

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