How to Tell If Grape Plants Are Producing

About 60 species of grapevines (Vitis spp.) exist in the world. The European grape (Vitis vinifera) is the leading type for production of wine, but in the United States, many native grapes have increased disease resistance or tolerance to winter cold. Fox grapes (Vitis labrusca) and muscadines (Vitis rotundifolia) are two examples. Modern cultivars of grapes typically produce flowers containing both male and female organs, increasing chances that the vine will self-pollinate and form fruits, botanically called berries, in summer. A healthy grape vine that is mature enough readily flowers and fruits. Grapes grow poorly in wet soils and if they don't receive ample sunshine.

• 1

  Lift up the young leaves on the grapevine in the mid and late spring months. Plants that never produce flowers cannot later yield fruits. Depending on your climate, grapevines display their tiny clusters of greenish yellow flowers in late spring to early summer, often attracting honeybees.

• 2

  Repeat the examination of the grape vines by lifting up the foliage in early summer. Look for small branching clusters of pea-sized light green grapes sheltered under the large grape leaves across the vines. According to James Kennedy of Oregon State University, 60 days after grape flowers are pollinated, the tiny grapes remain small while the seeds inside develop and slowly but eventually the green grapes begin to enlarge.

• 3

  Look across the vines in late summer to see large clusters of grapes, still partially hidden by the foliage. Rapid size increase occurs in this second growth period, leading up to harvest. Hungry birds may swoop and pluck grapes for a meal and denude a grapevine of fruits, leaving nothing but barren stems.

• 4

  Stoop down and look at the ground underneath the grapevines in summer and fall, too. If the plant did flower and yield small or immature fruits and they were aborted, you can find their dried skins or other debris. This provides insight into whether the grapevine flowered at all that year or if something happened that caused immature fruits to drop. Further investigation reveals if insects, animals or disease compromised the vine's fruits.