Strawberry Soil Requirements, Cultivation Systems, and Plant Density

Strawberry Soil Requirements and Best Pre-Planting Practices for Healthy Crops

Soil requirements and pre-planting practices

Strawberries have different soil requirements depending on the variety and the region. The plant can adapt to many soils but prefers well-drained, rich-in-organic matter, medium, sandy-loam, or loam soils with a pH of 5.5-6.5. Areas that remain wet late into the spring or are prone to frost are not appropriate for strawberry cultivation. The field should have full sunlight exposure and a small slope. This helps prevent frost injury by allowing cold air to drain away from the plants.

Before planting, the farmer can conduct a soil analysis in his/her field to determine some fundamental soil characteristics (e.g., soil type, nutrient availability, pH, etc.). You can review the cropping history of the field and avoid planting strawberries in places previously cultivated with Solanaceous crops (such as tomatoes, potatoes, and peppers) to reduce the risk of Verticillium wilt disease damage. Recently plowed grass or sod areas should also be avoided due to the high likelihood of significant weed problems and damage by white grubs (a common turf pest that also feeds upon strawberry roots). Farmers can use common soil treatments for soil-borne pests and weeds to clean/sanitize the fields, like soil fumigation and solarization. These measures can reduce important strawberry fungal diseases like anthracnose, Phytophthora crown rot, red stele, and gray mold. On the other hand, oats, rye, or Sudan grass can be cultivated (for green manure) and incorporated into the soil just before strawberries are planted in the field.

Cultivation systems used in strawberry production and plant spacing

The plants can be grown in matted-row systems, hill systems, or mound systems, raised beds with plastic mulch, high- and low-tunnels, and glasshouses. Strawberry producers, especially in the Mediterranean region, often use matted-row systems, hills with raised beds covered with plastic mulch, and high- and low-tunnels.

Large commercial farms often use the matted-row system for strawberries due to its cost-effectiveness and compatibility with mechanical harvesting. This method works well in cooler climates and is ideal for June-bearing varieties. In spring, growers plant strawberries in rows spaced 30 inches to 3 feet apart (75–100 cm) with plants 15–35 inches (40–90 cm) apart within rows, leaving 6–14 inches (15–35 cm) for runner spread. Anything outside that range can be cut off. Plants are typically thinned to a density of 10,000–40,000 plants per hectare (4,000-16,160 plants/acre). Flowers that bloom during the growing season are cut off.

The hill or mound system is mostly used in the regions where day-neutral varieties are cultivated. Planting takes place in the summer or the winter. The raised beds are around 8 inches in height (20 cm), usually covered with clear (transparent) or black plastic mulch. This can help prevent weeds from growing and maintain soil moisture. Most importantly, the hill system costs 30-40% less than the other growing systems, the yields are increased by 35-40%, and fruits grow 3-10 days earlier. The type of strawberry determines plant spacing. Growers are advised to place the plants at 30-35 inches (75-90 cm) distance between the rows and 12-24 inches (30-60 cm) between the plants. By leaving 12 inches (30 cm) around the plant, we give them enough space to spread. Any runners outside that range can be removed. The average plant density for hill production is 50,000-75,000 plants/ha (20,200-30,300 plants per acre) in single or double rows.

High or low tunnels for growing strawberries are used mostly for day-neutral varieties to extend the season production. The plant density usually is around 43,000 plants per hectare (or 17,500 plants per acre). These are commonly used in the Mediterranean region. This method of growing results in 40-50% higher yields, and the fruits grow 20-30 days earlier than in the matted-rows system. It also includes raised beds covered with plastic. It is similar to the hill system but in a high or low tunnel. Additionally, placing beehives in tunnels increases pollination.

When planting in an open field, the farmer should choose a cloudy day or an afternoon hour to transplant the strawberry seedling to the ground. It is important not to cover the plant crown with soil but only the top of the roots.

Tabletop or raised gutter systems (raised beds) have become increasingly popular for cultivating day-neutral and June-bearing varieties. In this system, the plants grow in plastic trays-troughs 1.5m (5 feet) above the ground in a closed irrigation system. Generally, each trough could be 91.5cm (3 feet) long, 15cm (6 inches) deep, and contain 9 plants. Usually, 60 cm or 2 feet are left between beds. Some main advantages are the lack of dependence on the soil (fertility, type, etc.) and the need for weed management. Additionally, it allows precise irrigation and fertilization, early planting, extended cultivation period, and no plant damage due to soil-borne late-season diseases and insects. However, the farmer needs consistent and reliable water access to use this system.

Glasshouse production is also used with a higher plant density of around 12 plants per m² (120,000 plants/ha or 48,480 plants/acre). Despite that, this cultivation system is not commonly used in most parts of the world due to the higher costs, but it is very popular in Japan.

Another new and upcoming high-technology system for growing strawberries is called hydroponics. Hydroponics is a system used to grow plants without soil in special hydroponic substrates. This method has many advantages, but the yields are lower compared to the standard growing systems of strawberries. However, the wastage is 1% compared to the 20% when growing strawberries in the soil.

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