How to Grow Raspberry Plants in Pots
Adding fresh sweetness to summer delights such as pie, ice cream and cheesecake, raspberries are well worth space in the home garden. Raspberry plants (Rubus spp.) are grown in U.S. Department of Agriculture plant hardiness zones 3 through 9, depending on cultivar, and are available in varieties developed specifically for small-space growing. While it is tempting to select a raspberry based only on color and taste, consider growing habit, size and soil requirements before purchasing a raspberry for container growing.
Choosing a Variety
To grow raspberries in a container, look for thornless varieties that require no staking. Dwarf and compact varieties of raspberries make ideal container plants.
- The BrazelBerries® Raspberry Shortcake dwarf thornless raspberry (_Rubus idaeus '_NR7, USDA zones 5 to 9) has a rounded growth habit, rather than sprawling vines like wild raspberries, and does well in a container. Because of its compact size, this variety does not require trellising. Full-size fruits mature in mid-summer.
- Joan J (Rubus idaeus 'Joan J,' USDA zones 3 to 8) is another raspberry variety that performs well in containers. This thornless variety provides a large yield in a small space.
Raspberries are self-fertile, so they do not require two plants for cross-pollination.
Selecting the Right Container
Use a large 7- to 10-gallon container for raspberries. Wine barrels, food-grade barrels and decorative planters all make suitable containers for raspberries. Make sure the container has sufficient drainage, with 10 to 20 1/4-inch holes in the bottom. Use a 1/4-inch drill bit or use a hammer and 1/4-inch nail to add more drainage holes if necessary.
To make moving the planter easier when it is filled with soil, place the container on a plant dolly before filling.
To avoid toxins leeching into the plant, never use containers that are made of treated wood or those that have held chemicals.
After the last chance of frost has passed, place one raspberry plant in each container to prevent crowding. Fill a container to 3 inches below the top with high-quality potting soil or a mixture of equal parts compost, topsoil and sand. Raspberries like a soil pH of 5.6 to 6.2, which is slightly acidic. Test the soil mixture after planting with an at-home soil testing kit, and add 1 inch of peat moss to increase acidity if the soil pH is above 6.2.
Because there is compost in the soil mixture, it is not necessary to fertilize raspberries at planting.
Dig a hole twice as wide as the root ball and just deep enough so that, when the hole is filled, the surface of the soil comes 1 inch above the root ball. Water well after planting.
Raspberries require full sun, so place the container in an area that gets 6 to 8 hours of sun.
Caring for Raspberries
Raspberries grown in containers dry out more quickly than those in the ground. Check the moisture of the soil daily and water any time the soil is dry 1 inch below the surface of the soil. In the heat of summer, containers may require watering once or twice a day.
Fertilize raspberries every three weeks with a mixture of 1 tablespoon of fish emulsion and 1 gallon of water per cubic foot of soil. Raspberries are ready to harvest from early summer to mid-autumn, depending on the variety.
Because roots in a container are not insulated by the ground, the raspberries must be brought indoors over the winter. Before the first hard frost, move containers into an unheated garage, shed or basement where temperatures stay between 30 and 50 degrees Fahrenheit.