Can I Put Sawdust Around My Strawberry Plants?
Strawberries (Fragaria spp.) are prima donnas. Pampered and protected, they produce precious, sweet berries. Strawberry plants' cold-hardiness varies, with the cultivar "Lipstick" (Fragaria "Lipstick") hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9 and the June-bearing cultivar "Honeoye" (Fragaria x ananassa "Honeoye") hardy in USDA zones 4 through 9. All strawberry plants, though, require an annual cocktail of nutrients to produce flowers and fruits. Growers mulch the plants' shallow roots with several materials, including sawdust, to conserve moisture and provide shade.
Wild strawberries' more refined hybrid cousins tolerate some dappled shade and prefer slightly acidic, well-drained soil. Hybrids may flower in May and set fruit in June or bear throughout the summer. Soil holds reserves of phosphorus, potassium and minor nutrients such as calcium and magnesium. Strawberries gobble nitrogen, though, making carbon-heavy sawdust used as soil conditioner or mulch a potential competitor for the nutrient. Plants show signs of nitrogen deficiency by stunted growth and chlorosis, or yellowing, on lower leaves. Only a soil test can determine whether or not your garden's soil contains all the nutrients strawberries need to grow, bloom and produce fruit.
Poorly nourished plants are more likely than well-nourished plants to be targets of disease and insect pests. Strawberries must withstand many fungal diseases, including Verticillium wilt, anthracnose, powdery mildew and a variety of leaf spots and root rots, many of which lurk underground. Mulch such as sawdust provides vital protection against pathogen-bearing splashes from irrigation and rainfall. Mulch's ability to help keep soil moist suppresses populations of spider mites, which are strawberry pests prone to outbreaks in dusty conditions. Always place mulch around -- but not touching -- your strawberry plants' stems.
Sawdust as Mulch
A study published in 2002 by the International Society for Horticultural Science in "Acta Horticulturae" found that sawdust mulches did not affect flowering or fruiting of the strawberry cultivar "Zefyr" (Fragaria x ananassa "Zefyr"). It found the yield of fruit was higher, but not significantly higher, in sawdust-mulched plants than in plants mulched with shavings and plants with no mulch on their soil. More non-mulched plants contracted Verticillium wilt than mulched plants, and more rotted fruit occurred on plants with no mulch. No significant difference occurred between plants sawdust-mulched and non-mulched plants regarding Botrytis rot or leaf spot. The only drawback to sawdust may be its low nitrogen content. Sawdust is carbon-rich and competes for nitrogen. Therefore, nitrogen-hungry strawberry plants mulched with sawdust may require require extra nitrogen until the sawdust decomposes enough to be worked into the soil, returning its borrowed load of nitrogen to the plants.
Commercial growers often choose plastic as mulch and weed retardant for strawberries, but plastic does not allow water or light penetration and can cause overheating of soil. Pine or spruce needles make a well-ventilated mulch layer that admits water and contributes rather than takes away nitrogen.
If, however, you still prefer sawdust mulch, compost it before working it into soil or using it as mulch; spread the sawdust onto 100 square feet of soil, and mix 1 pound of slow-release nitrogen into the sawdust to hasten its decomposition. Adjust the amounts to your strawberry garden's size.
- Missouri Botanical Garden: Fragaria “Lipstick”
- Missouri Botanical Garden: Fragaria x Ananassa "Honeoye"
- Missouri Botanical Garden: Fragaria “Frel” Pink Panda
- Plants for a Future: Fragaria x Ananassa - Duchesne.
- Ask The Plant, Texas Plant and Soil Lab: Strawberries
- University of California Agriculture and Natural Resources: Fertilizer Management in Strawberry Production
- University of California Integrated Pest Management Online: Spider Mites
- University of California Cooperative Extension, Santa Cruz County: Strawberry Nutrient Management
- Oregon Forest Products Laboratory: Sawdust Mulches for Larger Crops, Better Soils
- Virginia Cooperative Extension: Mulches for the Home Vegetable Garden
- Cornell University: Mulches for Landscaping
- Clemson Cooperative Extension: Composting
- 2005 Proceedings, Mississippi Water Resources Conference; Leaching of Nitrogen, Phosphorus and Potassium from Sawdust Amended with Chicken Litter; Nicholas R. Hatten et al.
An avid perennial gardener and old house owner, Laura Reynolds has had careers in teaching and juvenile justice. A retired municipal judgem Reynolds holds a degree in communications from Northern Illinois University. Her six children and stepchildren served as subjects of editorials during her tenure as a local newspaper editor.