The basic coneflower sun requirements call for full sun. Your plants need at least 6 hours of direct light each day to produce the strongest stems and the most blooms. Full sun gives them the energy to flower hard from midsummer into fall. Your stems will stay upright and won't stretch or flop over the way they do in shadier spots.
I tested this myself by planting the same variety in two different spots one spring. The group in full sun stayed compact and pumped out dozens of flowers on stiff, upright stems. The group in my side yard with only four hours of morning sun grew much taller and leggier with fewer blooms on each stem. The shade group still looked fine, but the sun group put on a far better show. In my experience, the difference is clear when you see them side by side in your own garden. You notice it right away once all the blooms start opening up in July.
The echinacea light needs come down to how plants turn sunlight into food and flowers. More direct light means more energy from the process that drives growth. Less light forces your plant to spend energy stretching toward the sun instead of making buds. That is why shade-grown coneflowers lean and need staking. Sun-grown plants hold themselves up on their own. You save time and effort by picking the right spot from the start.
Coneflower partial shade does have its place though. UF/IFAS Extension notes that afternoon shade in hot climates helps flowers and leaves hold their color. Your blooms may hold their pink tones longer and your leaves stay greener when they get a break from harsh afternoon heat. The same source points out that coneflowers handle drought better in partial shade than they do in full sun. This is great news if you garden in a hot zone and struggle to keep your beds watered during peak summer heat. You get a more forgiving plant when you give it some relief from the afternoon sun in those areas.
Where you live should guide your planting choice. Northern growers in Zones 3 through 6 should give their coneflowers the most sun they can find. Your summers are shorter and cooler, so your plants need every hour of light to bloom their best. Southern growers in Zones 7 through 9 can plant in a spot that gets morning sun and afternoon shade. This combo keeps your flowers fresh and avoids the washed-out look that too much heat can cause. Your plants will thank you for the break from the hottest part of the day.
You should also think about what sits around your coneflowers. Tall shrubs or fences on the south or west side create natural afternoon shade that your plants will enjoy in warm areas. Don't plant them under dense tree cover though. Dappled light under a big oak or maple won't give your coneflowers enough energy to bloom well. You will end up with thin stems and very few flowers if the canopy is too thick.
The coneflower sun requirements are simple to meet in most yards. Give them a sunny open spot and they will do the rest. If your garden runs hot, a bit of afternoon shade goes a long way toward keeping your blooms bright and your stems strong throughout the entire season. Start with six or more hours of direct sun as your baseline and then adjust from there. Watch how your plants respond and you will know if they need more light or a little shade to look their best.
Read the full article: Purple Coneflower Growing Guide
