The Watering of Thompson Seedless Grapes

Young Vines

• Water young Thompson grapevines regularly during the first growing season. With ample water, the vines will develop long, healthy root systems that support sturdy, healthy plants able to tolerate harsh weather conditions. Give new plants 2 gallons of water three times every week during the first warm, dry month in spring -- usually May or June. For the remainder of the first season, water the grapes once weekly, providing 4 to 5 gallons per vine.

Mature Vines

• In early spring, mature Thompson grapevines need only a total of 2 to 3 inches of moisture evenly distributed between early May and early June. Between the time that the grapes bloom in early June and when they start to ripen and turn soft in August, the vines will benefit from a total of 8 to 10 inches of water. At this point, the grapes will continue to develop until harvest without supplemental irrigation, but they can benefit from irrigation during periods of hot, dry weather.

Irrigation

• If you live in a hot, dry climate or if your late summer and early autumn are unseasonably dry, give Thompson grapevines one deep, thorough watering in early winter, just before the first expected hard freeze of the season. Water slowly, providing enough liquid to saturate the soil around the roots. A thorough watering ensures that the roots are well-hydrated, as dry roots are more susceptible to winter damage caused by repeated freezing and thawing.

Soil

• Choose a planting site with care, as Thompson grapes prefer sandy soil and don't do well in rich soil or heavy clay. Deep, loose, well-drained soil is critical, as the grapevines don't tolerate standing water or mud. If the ground is too damp or becomes compacted, air is unable to reach the roots. Eventually, the roots may suffocate and rot, causing the death of the vines.