Goldenrod is among the easiest native perennials to multiply, because it spreads on its own underground and sets plenty of seed. Most gardeners can start new plants from a clump they already have, with no special equipment. The same vigor means some kinds can take over a bed, so choosing which goldenrod to propagate matters as much as how.
Which Propagation Method to Choose
Each method has a different speed and payoff. Division gives you a flowering-size plant the same season or the next. Seed-grown goldenrod usually takes until its second year to bloom well. Seedlings can also differ from the parent plant, while divisions and cuttings are exact copies. So copy a plant you love by division or cutting, and use seed when you want many plants cheaply.
Your starting point narrows the choice quickly. If you only have a neighbor’s clump, divide it or take cuttings. If you only have a seed packet, plan on seed with a cold period. To fill a meadow, direct sowing in fall covers the most ground.
Timing follows the seasons. Sow outdoors in late fall, or start chilling seed indoors in winter. Divide in early spring as shoots emerge, or in fall after bloom. Take cuttings in late spring from soft new shoots. Skip moving plants in midsummer heat, when roots dry out fastest.
Seedlings vary because goldenrods are mostly cross-pollinated by insects, so a seed from your plant has a second, unknown parent. Nearby goldenrod species can also cross, so seed saved from a garden with several kinds may produce in-between plants.
Growing Goldenrod From Seed
Many goldenrod seeds sprout better after a spell of cold, moist conditions that mimics winter. In spike goldenrod, germination kept rising with up to 10 weeks of chilling at about 41°F.1HortScience. Stratification Improves Seed Germination of Five Native Wildflower Species In tall goldenrod, 4 weeks of chilling roughly doubled germination, from 35% to 71%.2Weed Science. Effects of seed stratification on germination of four weedy rangeland forbs Gains level off after 4 to 6 weeks.3HortScience. Stratification Improves Seed Germination of Five Native Wildflower Species About 6 weeks in the refrigerator is a practical target for most goldenrods.
Some goldenrods don’t need the cold. Giant goldenrod seed showed no dormancy and kept its vigor under many storage conditions.4Acta Physiologiae Plantarum. Do the seeds of Solidago gigantea Aiton have physiological determinants of invasiveness? Others are less forgiving: seed stored dry at room temperature for 3.5 years sprouted far worse than seed stored 6 months, and more of it was dead.5Biodiversity Research and Conservation. Seed germination in <i>Solidago ×niederederi</i> (Asteraceae) and its parental species after two different fruit storage periods So sow seed within its first year, and chill it anyway, since chilling rarely hurts and helps many kinds.
If you collect your own seed, wait until the flower heads turn fluffy and gray-white, usually in fall. Snip the heads into a paper bag and let them dry for a few days. Rub the heads to free the tiny seeds, each with a feathery tuft. Label the bag with the plant and date, since freshness matters.
To chill seed in the refrigerator, mix it with slightly damp sand or put it on a moist paper towel in a sealed bag. Keep it in the fridge, not the freezer, for about six weeks, and check weekly that it stays damp but not soggy. Sowing outdoors in late fall lets winter do the chilling for you.
Press the seed onto the soil surface without burying it, since it needs light to sprout. A thin dusting of fine sand or a gentle press with a board or your palm is enough; covering with potting mix is the most common reason seed fails.
After chilling, seed sown indoors in a bright spot at room temperature often sprouts within a couple of weeks, though some seeds come up later. Keep the surface moist until sprouts appear, watering from below or with a fine mist, because a heavy stream washes the tiny seeds and seedlings out of place. The seedlings start as tiny rosettes of small leaves that can look like weeds, so label the pots when you sow.
Move seedlings to their own pots once they have a few true leaves. Before planting, give indoor seedlings a few days of gradual exposure to outdoor sun and wind, or the leaves can scorch. Plant out after the last frost, once roots fill the pot enough that the root ball holds together when slid out. Water the new transplant well and keep it evenly moist for its first weeks while the roots spread into native soil.
Dividing a Goldenrod Clump
Most goldenrods spread by underground runners, which send up new shoots. Pieces of runner can sprout on their own; giant goldenrod pieces regrew 85% of the time.6Biological Invasions. Strong regeneration ability from rhizome fragments in two invasive clonal plants (Solidago canadensis and S. gigantea) Canada goldenrod pieces regrew only 19% of the time, and none came up from 8 inches deep.7Biological Invasions. Strong regeneration ability from rhizome fragments in two invasive clonal plants (Solidago canadensis and S. gigantea) So give each division plenty of root and plant it shallowly, about as deep as it grew before.
You’ll know a clump needs dividing when the center goes bare or weak while shoots crowd the edges. Flowering that drops off after several years is another sign, as are shoots popping up well beyond where you planted it.
Early spring works well because shoots are short and the weather is cool and moist. Dividing in fall after bloom gives roots time to settle before winter. Dividing while goldenrod is tall and in bloom stresses it, so if you must, cut stems back and water consistently.
Water the clump a day before so the roots hold soil. Dig around the clump and lift it with a fork. Pull or cut it into fist-sized pieces, each with several shoots. Each piece needs roots attached, since a piece with only stem may not recover. Discard the old, woody, bare center and keep the vigorous outer growth, which establishes faster. Trim tall stems back by half to reduce water loss.
Dig the hole wide enough that roots spread out instead of bunching, and set the crown at the same level as before. Space divisions according to the kind: running types need room to fill in, while clumping types need less. Firm the soil around the roots to remove air pockets, then water thoroughly so soil settles against them. Keep it moist for the first few weeks.
Soil was the biggest factor in whether goldenrod transplants survived.8Castanea. Effects And Importance of Soil Wetness And Neighbor Vegetation on Solidago Verna M. A. Curtis ex Torrey & A. Gray (Spring-flowering Goldenrod) [asteraceae] Transplant Survivorship and Growth Survival was lowest where water pooled or flooded.9Castanea. Effects And Importance of Soil Wetness And Neighbor Vegetation on Solidago Verna M. A. Curtis ex Torrey & A. Gray (Spring-flowering Goldenrod) [asteraceae] Transplant Survivorship and Growth Clipping back nearby plants also tended to help.10Castanea. Effects And Importance of Soil Wetness And Neighbor Vegetation on Solidago Verna M. A. Curtis ex Torrey & A. Gray (Spring-flowering Goldenrod) [asteraceae] Transplant Survivorship and Growth So plant divisions where water drains away, and clear competing growth around them.
Rooting Goldenrod From Stem Cuttings
Like many perennials, goldenrod roots best from soft, non-flowering shoots taken in late spring. Cuttings about 3 to 4 inches long are standard. Rooting hormone can help but is not essential for vigorous perennials.
Pick healthy, firm, medium-thickness shoots that are still growing and flexible, not tough woody stems or thin weak ones. Take them from the tips of shoots with visibly leafy growth, and take several, since not all will root. Shoots should be free of flower buds, because a bud signals the stem is shifting toward blooming; if there is one, pinch it off.
Cut just below a leaf joint in the cool morning. Strip the lower leaves and stick the stem in damp perlite or seed mix. A cutting has no roots to replace water lost through its leaves, so large leaves can be trimmed to about half their size. Cover loosely with a clear bag or dome to hold humidity, out of direct sun, and open the cover occasionally for air flow, which helps prevent mold. After two to four weeks, gently tug; resistance means roots. Soggy mix rots the base, and hot direct sun wilts cuttings before roots form.
Where New Plants Establish Best
A layer of dead leaves or thatch strongly held back goldenrod seedlings from coming up.11PubMed. The effects of size of opening in vegetation and litter cover on seedling establishment of goldenrods (Solidago spp.) A mat of litter keeps tiny seeds from reaching soil and shades them from the light they need. That’s why a lawn or mulched bed is a poor place to scatter seed without clearing first.
Seedlings also grew bigger and survived better in larger gaps in surrounding vegetation.12PubMed. The effects of size of opening in vegetation and litter cover on seedling establishment of goldenrods (Solidago spp.) Canada goldenrod seedlings survived only in gaps at least 12 inches wide, while gray goldenrod coped with more crowding.13PubMed. The effects of size of opening in vegetation and litter cover on seedling establishment of goldenrods (Solidago spp.) So rake sowing spots to bare soil and clear a circle at least a foot wide.
Choose full sun. In shade, goldenrod tends to stretch toward light, leaving tall weak stems that flop over, and it usually blooms less, which defeats the purpose of a pollinator planting. At least six hours of direct sun is a good target for most kinds. Avoid low spots that hold puddles after rain.
Giant goldenrod grew largest with plenty of water and nutrients.14PubMed. Do water and soil nutrient scarcities differentially impact the performance of diploid and tetraploid Solidago gigantea (Giant Goldenrod, Asteraceae)? So keep young plants evenly watered their first season, watering when the top inch of soil dries. Skip heavy fertilizer, which mostly feeds lush leaves. Established goldenrods tolerate poor, dry soil well. Mark young plants so you don’t weed them out.
Keeping Goldenrod From Taking Over
Canada and giant goldenrod spread widely by underground runners and are invasive in parts of Europe and Asia.15Biological Invasions. Strong regeneration ability from rhizome fragments in two invasive clonal plants (Solidago canadensis and S. gigantea)
Clumping kinds such as showy and stiff goldenrod spread mainly by seed and slowly widening clumps, so they are easier to keep in place and suit small beds. Spread varies by species and by soil, so a plant labeled as well-behaved at a nursery is a safer start than an unknown wild plant. If you aren’t sure which kind you have, watch its first season: shoots appearing well away from the main clump signal a runner type.
To hold a plant in bounds, sink an edging barrier around runner types and divide every few years. Cut flower heads before they seed if you don’t want volunteers.
Canada goldenrod also releases substances that can slow other plants’ sprouting. Avoid sowing small vegetables right where goldenrod grew, and give companion plants space so they aren’t crowded out.
To remove a runner type you no longer want, dig out as much of the underground runners as you can, following them through the soil rather than just lifting the visible clump. Pull new shoots as they appear over the following season, because leftover pieces will send them up. Repeated cutting of shoots before they bloom weakens the plant over time as it runs short of stored energy. Digging out a spreading goldenrod rarely removes it in one try.
Does Goldenrod Cause Hay Fever
Goldenrod flowers make nectar and have large, heavy pollen that sticks to insects.16Home & Garden Information Center. How to Tell the Difference Between Goldenrod and Ragweed Ragweed has no nectar and relies on wind to spread its light pollen.17Home & Garden Information Center. How to Tell the Difference Between Goldenrod and Ragweed Ragweed blooms at the same time and is usually behind late-summer hay fever.18Red Stem Native Landscapes. Late Summer Allergies: Goldenrod or Ragweed? Growing goldenrod is unlikely to add airborne pollen to your yard. People link goldenrod to allergies because its yellow flowers are conspicuous while ragweed’s greenish ones go unnoticed.
The two are easy to tell apart. Goldenrod has bright yellow, showy flower clusters and narrow, simple leaves. Ragweed has inconspicuous greenish flower spikes and deeply divided, fern-like leaves. People handling cut goldenrod closely may still notice mild irritation.
Allergy testing can show which pollens you react to, and that is the dependable way to learn whether goldenrod is involved. Checking your yard and nearby lots for ragweed first can show the likelier source.