Berries, Rhubarb and Asparagus
Raised beds are great for growing perennial fruits and vegetables. For starters, a raised bed isolates the perennial crop from invasive weeds and grasses that might creep into the growing area. Wind-blown seeds can get into the soil, of course, but the real enemies for these crops are grasses and weeds that creep into the plantings. All have shallow roots that don’t compete well with weeds and that can be damaged by aggressive weeding tools.
Some weeds and grasses are very aggressive and will attempt to climb up and over the edge of a raised bed. Ground ivy or creeping Charlie (Glechoma hederacea) is a common lawn weed that has no problem making it up, over and into an 8″-high raised bed. You can help hold it at bay by creating a 2 ft.-wide mulched strip around all four sides of the raised bed. Put down landscape fabric or black plastic sheeting and then cover that with bark mulch, chopped leaves or straw.
For More Information
Check our Vegetable Encyclopedia for more information about planting and care instructions for each of these crops.
Another advantage of raised beds is that you can start with soil that is specifically tuned to the needs of the plants. Blueberries, for example, require very acidic soil (in the range of pH 4.0-5.5). To prepare the ideal soil conditions, you can add elemental sulfur at planting time and then top-dress your blueberries each year after they bloom with an acidic fertilizer. Most other crops would suffer in such acidic growing conditions.
Asparagus and rhubarb both want rich soil amended with lots of compost or rotted manure, so they could be grown in the same bed. But a bed with nothing but asparagus in it is easier to manage (and it’s pretty difficult to have too much of it).
Strawberries need some special attention to avoid overcrowding and to prevent the fruit from rotting or being stolen by chipmunks and birds. Having a bed that contains nothing but strawberries makes it much easier to tend the plants and protect them with bird netting.
Raspberries and blackberries can spread aggressively by root. Growing them in a raised bed helps to keep them from taking over your lawn or garden. It also makes it much easier to get into the bed for picking and pruning. When the time comes for removing the canes that have produced and died, you will be able to reach them. An uncontrolled blackberry patch can easily become 10 feet wide in a few years, making it almost impossible to do a proper fall clean-up without getting badly scratched by the thorns.