Planting Instructions for Machaeranthera tanacetifolia (Lacy Tansyaster)
Here's a guide to planting Machaeranthera tanacetifolia, also known as Lacy Tansyaster or Tansyleaf Aster:
Site Selection
Sunlight: This plant thrives in full sun, requiring at least 6-8 hours of direct sunlight daily. It can tolerate some light shade, but flowering will be more prolific in full sun.
Soil: Machaeranthera tanacetifolia prefers well-drained soil. It is adapted to dry, sandy, or gravelly soils and tolerates poor soil conditions. It is important that the soil does not retain excessive moisture, as this can lead to root rot.
Planting Outdoors
Fall Planting:
Fall is an excellent time to plant.
Sow seeds in late fall (September-November, depending on your location) before the first hard freeze.
Prepare the soil by clearing any weeds or debris and lightly loosening the top layer. This species does not require rich soil, so amending with compost is usually unnecessary.
Scatter seeds on the surface of the soil. They need light to germinate, so avoid burying them too deeply. Pressing them lightly into the soil or covering with a very thin layer of sand or fine soil is sufficient.
Water gently but thoroughly. Keep the soil consistently moist until germination.
Spring Planting:
Sow seeds after the last spring frost.
Germination rates may be lower with spring planting compared to fall planting, so stratification (explained below) is recommended.
Follow the same planting steps as for fall planting.
Starting Seeds Indoors
Timing: Start seeds 6-8 weeks before the last expected frost in your area.
Containers: Use seed starting trays or small pots with drainage holes.
Soil: Use a seed starting mix or a well-draining potting mix.
Planting: Sow seeds very shallowly, barely covering them with soil. They need light to germinate.
Watering: Keep the soil consistently moist but not waterlogged. Use a spray bottle or gentle watering can to avoid disturbing the seeds.
Light: Provide ample light. A sunny window may not be enough, especially in early spring. Grow lights are highly recommended for starting Machaeranthera tanacetifolia indoors.
Transplanting: Transplant seedlings outdoors after the last frost and when they have developed a few sets of true leaves. Harden them off gradually before transplanting. Space plants about 1-2 feet apart.
Stratification and Scarification
Stratification: Machaeranthera tanacetifolia seeds benefit from stratification (cold treatment). This helps break dormancy and improve germination rates, especially for spring planting. Place seeds in a sealed plastic bag with a slightly damp paper towel or vermiculite. Store the bag in the refrigerator for 4-6 weeks before planting.
Scarification: Scarification (lightly scratching or nicking the seed coat) is not generally required, but it can sometimes improve germination rates. If you choose to scarify, gently rub the seeds with fine-grit sandpaper or use a nail file to nick the seed coat. Be careful not to damage the inner part of the seed.
Watering
Keep the soil consistently moist during germination and early growth.
Once established, Machaeranthera tanacetifolia is very drought-tolerant. Water deeply but infrequently, allowing the soil to dry out thoroughly between waterings. Avoid overwatering, especially in heavier soils, as this can lead to root rot.
Maintenance
Machaeranthera tanacetifolia requires minimal maintenance.
Deadheading spent flowers can encourage more blooms, but it's not necessary.
It may self-seed readily in ideal conditions.
Invasiveness
Machaeranthera tanacetifolia is not generally considered invasive. However, it can spread through self-seeding. If you want to control its spread, you can remove seed heads before they mature.
Additional Tips
Machaeranthera tanacetifolia is a great choice for wildflower gardens, rock gardens, and dry, sunny areas.
It attracts pollinators such as bees and butterflies.
This plant is deer-resistant.
Be patient with Machaeranthera tanacetifolia seeds. Germination can be erratic, and it may take several weeks for seedlings to appear.