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Planting and Care Instructions
Upon Receipt of Tubers
- Inspect Immediately: Open your package within 24-48 hours of delivery. Check each tuber for viability—look for at least one visible eye (growth bud) and ensure the tuber is firm, not soft, rotten, or moldy. We visually inspect every tuber before it ships at least two times, and we would never ship something that we wouldn't plant ourselves! So, if something has happened to the tuber please contact us with photos within 4 days if you receive damaged or non-viable tubers for a replacement or credit.
- Storage if Not Planting Right Away: If it’s too early to plant (before the last frost, typically mid-April to May depending on your zone), store tubers in a cool, dry, dark place (40-50°F) to prevent sprouting or rot. Use a breathable bag with peat moss, sawdust, or vermiculite to maintain slight humidity. Avoid plastic bags, which can trap moisture and lead to mold.
- Keep Packaging Materials: Retain the original packing slip and any included growing guide or tags for reference and in case of issues with your order.
Soil & Site Preparation
- Timing: Plant tubers after the last frost date in your area (check your USDA hardiness zone—typically late April to mid-May for most U.S. regions). Soil temperature should be at least 60°F.
- Site Selection: Choose a location with full sun (6-8 hours daily) and well-draining soil. Avoid low-lying areas where water pools, as dahlias are prone to rot in overly moist conditions.
- Soil Preparation: Enrich soil with organic matter like compost or well-rotted manure. Work the soil to a depth of 12-18 inches and remove rocks or debris. Bone meal can be worked into the soil where the tuber will be planted- about 1 tablespoon per hole will encourage tuber development.
Planting
- Digging the Hole: Dig a hole 4-6 inches deep and 12-18 inches wide, depending on tuber size and variety. Space plants 16-24 inches apart to allow airflow and growth.
- Positioning the Tuber: Place the tuber horizontally with the eye facing up (if identifiable) or on its side if unsure. Cover with 2-3 inches of soil initially, leaving the top exposed in some cases to monitor sprouting, then fill back up to the original soil line as it grows.
- Watering: Soil should be semi moist prior to planting. DO NOT water after the tuber is planted until you see an above ground shoot and a few leaves.
- Staking: Insert a stake or large cage 1-2 inches from the tuber at planting time for varieties expected to grow over 3 feet tall, to avoid damaging roots later. We like using T-posts for this step, due to their durability and strength.
Care
- Watering: Provide 1-2 inches of water weekly, ensuring the soil dries slightly between waterings. Increase during hot, dry spells, but avoid overwatering—excess moisture can cause root rot. Use a soaker hose or water at the base (we try to avoid overhead watering due to the possibility of powdery mildew developing- but, we have heard of other growers use this method without issue).
- Fertilizing: Apply a balanced, organic fertilizer (e.g., 5-5-5) or compost every 4-6 weeks starting when plants are 1 foot tall. Avoid high-nitrogen formulas, which promote foliage over blooms. Stop fertilizing in early September so the plant can focus on tuber development rather than above ground growth.
- Pinching: When plants reach 12-18 inches tall (about 4-6 weeks after planting), pinch the top set of leaves to encourage bushier growth and more blooms.
- Staking and Support: As plants grow (especially varieties over 3 feet), secure stems to stakes with soft ties (we use green jute string). Adjust as blooms develop.
- Deadheading: Remove spent blooms weekly to promote continuous flowering and prevent seed production, which can reduce tuber energy.
- Pest and Disease Management: Watch for aphids, spider mites, or powdery mildew. Use insecticidal soap or neem oil for pests, and ensure good air circulation to deter disease. Remove and destroy affected foliage—do not compost.
- Mulching: Apply 2-3 inches of organic mulch (e.g., straw or bark) around the base after sprouting to retain moisture and suppress weeds, keeping it away from stems to prevent rot.
More Questions?
For further assistance, reach out to us at Willamette Valley Dahlias by using the "Contact Us" form on our home page!
Mark Your Calendars!
Tuber sales go live on January 15th, 2026. Until then, only merchandise is available for purchase.