Small Fruits in Early Spring

Grapes to Brambles

By John Fulton

[March 24, 2008]  Many small fruits require special maintenance in the early spring for their longevity and to achieve high production. This would include operations on grapes, brambles, blueberries and strawberries.

Grapes should be pruned in the spring, and we are at the late time for pruning. The goal is to leave about six good buds per lateral on the vines. This late, there could be some serious "bleeding" of grapes. This happens when the sap has risen, and it occurs on high-sap-flow trees like maples as well. This bleeding is probably more damaging to you than the plants. There is no way to stop it, as there is nothing to plug or coat the ends when that much sap is being discharged.

Strawberries are rather labor-intensive in the spring. Hopefully they were mulched with straw last fall. They should be uncovered when the soil temperature is about 40 degrees at 4 inches deep under the mulch. This soil temperature can be checked with a regular soil thermometer or some type of cooking thermometer that has the lower temperatures. To use a thermometer without the soil point on it, you will need to dig a 4-inch hole with a trowel or spade and then put the sensing bulb against the bottom of the hole to get the temperature. If you start to notice yellow leaves, uncover the plants immediately regardless of the soil temperature. Keep the straw handy, as temperature fluctuations may require you to re-cover the plants. That's where the labor-intensive part comes in.

Brambles include blackberries and raspberries. Thorned blackberries should be done only in the spring. Start by cutting out all canes that produced last year. They will be gray in color. Also take out the small, weak canes and those that appear diseased. Try to leave canes about 8 inches apart. You can cut these back to about 18 inches long. Tipping canes in the summer is the process of simply breaking the tips off about 3 feet high. If you didn't do it last year, make a note on this year's calendar for late summer. This greatly increases fruit production since fruit comes on the lateral branches, not the main stem.

Thornless blackberries also need to be thinned. Start by cutting out the canes that produced last year. Cut canes back to live wood, and you can tell this by a dark, sunken area above the live wood. Then keep about eight of the best canes for each plant, removing everything else. Most of the time the thornless berries are grown on a trellis, so tie those new canes to the trellis throughout the year. Using old pantyhose works great for tying up plants. I'll leave it up to you where to find your supply of tying material.

Red and yellow raspberries that produce in the spring and fall should be handled like the thornless varieties of blackberries. There are a few varieties managed for a fall crop only, and in that case you simply mow everything to the ground.

Fertilizer is often asked about. For brambles, an even-analysis fertilizer such as 12-12-12 at the rate of 1.5 pounds per 100 feet of row is great. This is a little bit more than the recommended turf rate of 8 pounds per 1,000 square feet so beware if you are applying to turf areas.

Weed control is often asked about as well. Preen is labeled for many uses and will kill annual small-seeded broadleaves and grasses pre-emergence (the germinating seeds are killed). There are post-emergence grass products available from specialty stores.

[By JOHN FULTON, University of Illinois Extension, Logan County]