Learn About Cortaderia
How to Sow
How to Plant
Planting Potted Plants:
- Choose a location in full sun with moist, well-drained soil. Be sure to give the plant plenty of room to grow as it spreads to 3-4 feet wide.
- Prepare the bed by turning the soil under to a depth of 6-12 inches removing any debris, and lightly raking as level as possible.
- The addition of organic matter (leaf mold, compost, well-rotted manure) benefits all gardens and is essential in recently constructed neighborhoods.
- Plant on a cloudy day or in late afternoon to reduce transplant shock.
- Dig a hole for each plant large enough to amply accommodate the root ball.
- Unpot the plant and gently loosen the root ball with your hands to encourage good root growth.
- Place the top of the root ball even with the level of the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand.
- Use the plant tag as a location marker.
- Thoroughly water and apply a light mulch layer on top of the soil (1-2 inches) to conserve water and reduce weeds.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their germination.
- Mulches also help retain soil moisture and maintain even soil temperatures. For perennials, an organic mulch of aged bark or shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Careful watering is essential in getting perennials off to a good start. Water thoroughly at least once a week to help new roots grow down deeply. Soil should be damp at about 1 inch below the soil surface. You can check this by sticking your finger in the soil. Water early in the morning to give all leaves enough time to dry. One inch of rain or watering per week is recommended for most perennial plants. You can check to see if you need to add water by using a rain gauge.
- Until plants become established, some protection from extreme winds and direct, hot sunlight may be necessary. Good air movement is also important.
- After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer such as Garden-tone, as higher rates may encourage root rots.
- Many gardeners do not cut back perennial flower seed heads in the fall, but wait until early spring before the new foliage appears. This provides food for wildlife over the winter.
- Cortaderia is relatively low-maintenance and drought tolerant once established.
- Cut back to the ground either in late winter or spring. Be careful when you do this as the foliage can be sharp.
- Plants make a big statement at the back of the border, as a herbaceous hedge, as dried cut flowers.
Common Pests and Problems
Edema (Oedema): Leaves become distorted due to excess moisture in the soil. Plants absorb more water than they can use. Burpee Recommends: Do not overwater plants, keep the soil moist but not wet. If drainage is poor add compost or peat moss to improve drainage.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Rust: A number of fungus diseases that cause rust colored spots on foliage. Burpee Recommends: Remove infected plant parts. Contact your Cooperative Extension Service for recommendations.
Smut: This fungus attacks mostly young seedlings as the new leaves emerge. It causes blister-like lesions near the base of the plant and streaks on leaves. The streaks mature into black powdery spores. The fungus stunts the growth of the plants. More mature plants are not as susceptible. It is most prevalent in temperatures under 75 degrees F. The disease lives in the soil for several years. Burpee Recommends: Some fungicides are effective, Check with your Cooperative Extension Service for recommendations.
Common Pest and Cultural Problems
Cortaderia has few pest issues.
Winter Kill: Cortaderia is sensitive to colder areas and a severe winter may kill the roots. Burpee Recommends: In borderline hardiness zones provide extra winter protection, mulch the ground after it freezes. Remove the mulch in spring.
Can I grow cortaderia in containers? No, it is much too large!
Is cortaderia deer resistant? Yes, it is deer resistant.
Does cortaderia attract pollinators to the garden? Yes, it attracts birds to the garden.
Why didn’t my cortaderia bloom? It may be in too much shade, it needs 6 hours of full sun daily. Another possible reason could be if you fertilize too much this may cause green growth at the expense of flowers. Also, it blooms late in the season and it may be too early.
Do I need to divide my cortaderia? Yes, divide plants in spring breaking the pieces apart with a spade. Be careful as the leaves are sharp. Divide every 3-4 years.