Fertilizer for Arborvitae: NPK Guide and Application Rates
Arborvitae (Thuja) are low-maintenance evergreens that require minimal fertilization once established. The University of Minnesota Extension notes that arborvitae in reasonably fertile soil rarely need supplemental feeding. Annual fertilization is most beneficial for hedgerows that are regularly sheared, newly planted specimens, and trees in poor soil. Browning in winter is often caused by desiccation from wind and sun, not nutrient deficiency.
Quick Reference
What NPK Ratio is Best for Arborvitae?
The recommended NPK ratio for arborvitae is 10-8-6. The nitrogen-forward 10-8-6 ratio drives leaf and stem development, which arborvitae needs for photosynthesis and canopy growth.
Arborvitae NPK needs shift at each growth stage. Balanced formula for newly planted trees during the Seedling phase, then cones are insignificant; maintain consistent feeding once flowering begins.
NPK by Growth Stage for Arborvitae
| Growth Stage | NPK Ratio | Notes |
|---|---|---|
| Seedling | 10N 10P 10K N 10% Nitrogen: leaf and stem growth P 10% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Balanced formula for newly planted trees |
| Vegetative | 10N 8P 6K N 10% Nitrogen: leaf and stem growth P 8% Phosphorus: roots and flowers K 6% Potassium: health and disease resistance Learn more about NPK | Moderate nitrogen for dense evergreen growth |
| Flowering | 10N 8P 6K N 10% Nitrogen: leaf and stem growth P 8% Phosphorus: roots and flowers K 6% Potassium: health and disease resistance Learn more about NPK | Cones are insignificant; maintain consistent feeding |
| Fruiting | 10N 8P 6K N 10% Nitrogen: leaf and stem growth P 8% Phosphorus: roots and flowers K 6% Potassium: health and disease resistance Learn more about NPK | No seasonal change; stop feeding by September |
When Should You Fertilize Arborvitae?
In zone 3, start fertilizing arborvitae in May. In zone 8, begin as early as March. Apply every 10 weeks through the growing season.
Which Zones Can Grow Arborvitae?
Arborvitae grows in USDA zones 3 through 8, spanning a 6-zone range.
Fertilization Start by Zone
| Zone | Start Month |
|---|---|
| Zone 3 | May |
| Zone 4 | May |
| Zone 5 | April |
| Zone 6 | April |
| Zone 7 | March |
| Zone 8 | March |
What Are the Best Fertilizer Products for Arborvitae?
Look for products with an NPK close to 10-8-6. Espoma Tree-tone is the most popular choice among home gardeners for arborvitae.
- Espoma Tree-tone
- Espoma Holly-tone
- 10-8-6 evergreen fertilizer
Prices vary by retailer and region. Check current pricing before purchasing.
Container and Raised Bed Adjustments for Arborvitae
Dwarf varieties in 15+ gallon containers; feed once in spring with slow-release granular
Common Fertilizing Mistakes with Arborvitae
- Fertilizing in late summer or fall, promoting tender growth susceptible to winter burn.
- Diagnosing winter browning as nutrient deficiency when desiccation from wind is the cause.
- Over-fertilizing, which causes rapid, soft growth attractive to bagworms and spider mites.
- Planting arborvitae in poorly drained soil where no amount of fertilizer prevents root decline.
Tips for Fertilizing Arborvitae
- Apply evergreen fertilizer in early spring before new growth begins.
- Sheared hedges benefit more from fertilization than unpruned specimens due to increased growth demands.
- Water deeply in late fall before ground freezes to prevent winter desiccation browning.
- Maintain a 3-inch mulch ring around the base but keep mulch away from the trunk.
Organic Fertilizer Alternatives for Arborvitae
Sources
Source:Clemson University ExtensionLast updated: