How Deep a Planter Do Raspberries Need?

Average Depth

• Raspberries grow on canes, or stems, that have thin roots just below the soil line. To adequately supply enough nutrients to these roots, your planter depth should range between 12 and 15 inches deep with an approximate 15 inch diameter. Only one plant should be grown in this planter size because multiple plants in such a confined space often compete for moisture and nutrients. Your raspberries may fail to fruit if they are too crowded. If you want to raise more raspberries, use multiple planters placed in the same growing location. Watering and basic maintenance is streamlined with the canes growing near one another.

Root Habit and Planter Basics

• Raspberry roots are extremely shallow, making them well-suited to a planter environment. When you place your young raspberry plant in the container, all the roots should be within the top 2 inches of soil. Any new shoots growing into the sunlight must not be impeded by heavy soil from a deep planting. The remaining planter depth is dedicated to organic matter and potting mix. Raspberries need a lot of soil nutrients available to produce fruits, along with consistent watering. As the roots establish themselves, they slowly spread horizontally to form anchors in the soil for future fruits and tall canes.

Encouraging Drainage

• Adding organic matter to your planter's basic potting mix provides the well-drained planter environment necessary to avoid root rot. Raspberries do not withstand soggy conditions for long periods and often succumb to root rot. Fungi and bacteria thrive in wet conditions as they slowly decay the roots. Do not overwater your raspberries and use a planter that has drainage holes. If you raise more than one plant in multiple planters, space them apart by several inches to increase air flow around the canes. Sufficient air flow provides soil evaporation for a damp, but not soggy, planter habitat while increasing available carbon dioxide for photosynthesis.

Incorporating Support

• Because your raspberry roots are confined to the planter's diameter, they cannot spread out horizontally to fully support the canes and fruits -- even garden-grown raspberries need some trellising support. Add one or more small poles to the planter and tie the heavy canes to them using plant ties. Locate your planters in a sheltered area away from high winds. Your poles easily hold the canes because the planter's depth provides some anchorage for the support system, but extreme winds knock plants over and damage them.