Because raspberries are so tough to pick, package and transport at peak ripeness, growing raspberry plants at home is often the best way to fully enjoy this fruit. Like blackberries, they are members of the genus Rubus, and numerous cultivars offer a range of characteristics. Raspberries are typically classified by their fruit color and whether they are summer-bearing, producing one crop in summer, or everbearing, with multiple crop times. These plants are fairly easy to cultivate if a good site is selected and prepared, and routine maintenance occurs.
Caring For Raspberries
Raspberries typically perform best in full sunlight, although in particularly hot areas, some protection from intense afternoon sun is ideal. Raspberries also benefit from trellising or other supports to keep fruit off of the ground, protect against wind damage, and make harvest easier. Regular weeding is an important aspect of raspberry care, as is routine watering when rainfall is insufficient. Pruning happens in spring to remove weak canes and cut back tall canes, and after fruiting, spent fruiting canes can be removed.
Good site selection and preparation prior to planting will ensure raspberry plant vigor and fruit yield. These plants prefer a well-drained sandy loam with a pH between 5.5 and 7. If the soil is compacted or has a high clay content, break up the soil to a depth of at least 2 feet, and work in ample organic matter such as compost. When planting, space multiple plants 18 inches to 3 feet apart. Keep rows spaced at least 6.5 feet apart. The best time to plant raspberries is early spring.
Raspberries need consistent soil moisture to become established and produce maximum yields. These plants do not like to have their roots dry out or to sit in standing water. Following planting, keep the root zone moist but not soggy by watering multiple times per week until the plant is established. Once established, raspberries typically require an inch to an inch and a half of water weekly through rainfall and supplemental irrigation. With each watering, slowly apply water to moisten the top 6 inches to a foot of soil. Soils with a high sand content will require more frequent watering than high-clay soils.
Begin routine fertilizer applications at the start of blooming the second year. Use a balanced, slow-release fertilizer like a 10-10-10 formula at a rate of 2 ounces of nitrogen per 10 feet of row. The following year and beyond, apply feed at a rate of 2 to 3 ounces of nitrogen per 10 feet of row. Raspberries perform best if fertilizer applications are divided into two separate applications. The first should occur when canes start to grow. Follow with the second application 6 to 8 weeks later. Monitor for a nitrogen deficiency, which appears as pale green or yellow leaves on first-year canes. Excessive nitrogen causes tall, thin canes with a lot of space between leaves on the cane.
Growing Raspberries In Pots
For growers with limited garden space or poor soil, it may be preferable to grow raspberries in containers or raised beds. Dwarf, thornless varieties are best suited for this situation. Everbearing types pruned to produce two crops each year are also preferable. Raspberries are relatively deep rooted, so look for a container with a minimum depth of two feet. A 20 to 30 gallon container with ample drain holes is ideal. To ensure good drainage, use a high-quality potting mix. Plants in containers may require much more supplemental irrigation than their in-ground counterparts and must be pruned to stay compact enough for the container.
Some raspberries grow vegetatively for one year and then fruit on those canes the next year, so these types may not offer fruit to harvest the first year following planting. Ripe fruits are fully colored and easy to gently remove from the plant. A productive plant will require picking every 3 to 4 days; if an extended period of wet weather is expected, pick nearly ripe fruits to avoid diluted flavor and fruit rot. If possible, do not harvest the fruits when they are wet from dew or rain and do not wash fruits prior to storage, as this will encourage rot. Store fruits in shallow containers to minimize crushing and refrigerate them to prolong shelf life.