Tuesday, March 21, 2017

Growing Raspberries, part 3

(internet photo)


Once you've selected the type of raspberries you want to plant, prepared the raspberry planting area, and put the plants in the soil, it's time to think about how to care for them, to make it easier for them and for you.

Raspberries benefit from growing on some sort of support structure to increase light penetration to the canes, thus increasing fruit production; and to minimize the incidence of diseases related to overcrowding of the foliage. Those of us picking them benefit from that support structure as well - it's much easier to pick berries that readily accessible than it is to dig around in a thorny thicket. It's also easier to keep the weed population down when the raspberry plants themselves are supported and not lying on the ground. That said, if you choose to not trellis your raspberries, that works, too. 

Raspberries can be supported with a t-trellis, a v-trellis, or a hill or i-trellis system. Plants grown in rows are best trellised using the t-trellis or v-trellis system, while those that are planted in hills will do well with a simple hill system trellis.

T-trellis (internet photo)



A t-trellis is formed by using a 6-foot long 4 x 4 post set in the row. The post should be set two feet in the ground and tamped in solidly. The remaining four feet above ground should have a cross-arm anywhere from 20 to 30 inches wide, fastened a few inches from the top of the post to form a T. One t-post is placed at each end of the row. For rows longer than 4 to 6 feet, you will need to place additional t-posts in the middle of the rows to provide enough support. For shorter rows, a t-post on each end of the row should suffice. Once the posts are set, string heavy gauge wire from post to post on each side of the T, and train the raspberry bushes to grow between the two wires. For a sturdier trellis, you can place a second crossbar mid-way between the top crossbar and the soil and string a second wire between posts.

A v-trellis is formed by setting two posts at each end of the row and setting them at a 30 degree angle outward from the center of the row. The tops of the posts should end up about 30 inches apart and 3 1/2 feet tall. A heavy gauge wire is strung from post to post on either side. A v-trellis is stronger than a t-trellis, but is a bit more challenging to set the posts at just the right angle. As with the t-trellis, the raspberries are trained to grow between the two wires. 

V-trellis (internet photo)


An i-trellis or hill system is the simplest to build. It's a matter of sinking a sturdy post next to each raspberry plant and using a wire to train the raspberry foliage next to the post. You can string a heavy gauge wire between the posts to support longer canes. This only works well for raspberries planted in hills, rather than rows.
Hill trellis (internet photo)

The trellises will help you keep your raspberries growing where you want them to grow, but you will still need to use shallow cultivation and mulch to keep weeds and suckers in check. Mulch has the added benefit of holding soil moisture more constant, which will increase fruit production. Organic mulch is always the best. Wood chips, bark, leaf mold, or similar materials can be spread between and around the rows to a depth of about three to four inches. After the raspberries are well established, usually the year after planting, a cover crop of annuals such as oats or millet can be planted between the rows. At the end of the growing season. you can either allow the crop to rot into the ground on its own, or till it in to add organic matter to the soil.

After the second season of fruiting, you could opt to use a permanent cover crop such as a low water use grass. Planting grass requires that you keep it mowed and prevent the roots from sneaking into the raspberry rows. This is not my favored way of mulching, as it is much more maintenance than a good solid wood mulch that biodegrades into the soil slowly.

Raspberries require about an inch of water each week to do their best. If supplemental irrigation is necessary, it is best to irrigate using a drip system to keep the foliage dry. If you need to use overhead irrigation, always try to irrigate in the morning so that the sun and wind can dry the foliage quickly to avoid disease problems.

In addition to water, raspberries need food. The patch should be fertilized each spring, just at the start of foliage growth, using 10 pounds of 10-10-10  fertilizer per 1000 square feet of berry patch. If you use a heavy mulch, you should increase the application rate to 12 pounds to adjust for the nitrogen that can be used up by the breakdown of the mulch. A second application should be made four to six weeks later.

To maintain healthy a raspberry patch, the bushes must be pruned each year. It reduces the spread of diseases that can wipe out your patch, and increases the size and quantity of the fruits. Throughout the growing season, ruthlessly remove any suckers that spread out beyond 18 inches from the parent row. This will help you keep the spread of each row in check for easier picking and better airflow between the rows. Watch for and remove any canes that don't look quite right - dying leaves, black tips, or insect chewing on the bark itself. This will help you keep diseases and insect infestations in check.

At the end of each growing season, remove all of the old canes that have borne fruit that year. You will be able to tell these canes by their grayish, peeling bark and dead branches. The raspberries should also be thinned to only four to five canes per foot. Leave the thickest, sturdiest canes and trim others down to the soil level. Cut the remaining canes back to about 12 inches and attach them to the trellis wires with a soft twine to keep them growing upright and within the trellising system.

Ever-bearing raspberries will produce two crops each season if pruned this way.  The summer crop will be produced on the previous year's canes and the fall crop will be on the new growth canes. The fall crop will be less productive with smaller berries, but there is generally enough to give you a few really nice raspberry treats. If you choose, you can mow the ever-bearing raspberries back to ground level in early spring. You will sacrifice the summer crop, but will have a much better fall crop. I prefer to use this method of pruning. It is much easier than trying to pick and choose just the right canes. I manage a full season of raspberries without two crops from the everbearing varieties by planting numerous varieties with different production times. It is nice to have the ever-bearing crop in later fall to extend that good-eating season just a little bit longer.

Always, always, always remove all your pruning debris from the patch and destroy it, either by burning it or taking it to the landfill. Raspberries can harbor diseases and pests and are not the best suited for the compost pile.

Now, for the rewards for all that labor! Raspberries are ready to pick when a very gentle tug on the berry separates it from the core. During peak raspberry season, they need to be picked nearly every day. Their peak flavor and texture does not last very long, either on the bush or after they are picked. When picked, they should be stored in shallow layers and refrigerated immediately. If they are cooled to around 35 degrees shortly after picking, you can keep them in storage for three to five days before eating, freezing, or making into wonderful jams.

A well cared for raspberry patch can produce fruit for 10 to 20 years. That's a lot of good eating!

(internet photo)