This is another post in my monthly series about small fruits that can be grown sustainably in a vaguely mid-Atlantic climate. I cover planting, pruning, harvesting and care of the plants, according to the season. I’ll give links to useful publications. We have a focus fruit, and then more about others that need attention during the month.
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Grapes are the focus fruit for August
The Cornell 2022 Organic Production and IPM Guide for Grapes 2022-org-grapes-NYSIPM.pdf (3.291Mb) is a great resource. It covers soil health, pre-planting and under-vine cover crops, site selection, variety selection, nutrient requirements, integrated pest management, and more in its 90 pages. Be aware that it is written with the Northeast in mind.
For a more general approach, see Grapes: Organic Production. ATTRA, Rex Dufour, 2006.
If you are planning to grow grapes, late summer is a good time to prepare the site and sow a cover crop to suppress weeds, increase the organic matter in the soil, and if you include legumes, provide some slow-release nitrogen for the new vines.
Types of grapes
Grapes are a long-term perennial crop, so good research into suitable types and varieties is important. Wine grapes (Vitis vinifera) and table grapes do not grow well organically on the east coast, because of fungal diseases. Mars is a table grape that grows relatively well organically. It resembles Concord. Vitis Labrusca grapes (Concord, Niagara, etc) are much less susceptible than Vinifera varieties. Hybrid Grapes (Labrusca x Vinifera), such as Arandell, Cayuga White, Corot Noir, Noiret, and Traminette have better potential for Organic culture than Vinifera types.
We grow Labrusca grapes, mainly Concord, with a few Allred, with a selection of other varieties that we are trialing, including the Planets (Jupiter, Mars, Neptune, Venus) and Edelweiss, Fredonia, Marquis, Niagara, Reliance, Sheridan, Steuben, Vanessa. All these are suitable for juice, jam and jelly. Fredonia, Marquis, Mars, Niagara, Reliance, Steuben, Vanessa and Venus are dessert quality, but mostly they have thick skins, big seeds, and a sour taste. Some of these varieties are susceptible to Downy Mildew, Powdery Mildew and/or Black Rot, and I wouldn’t buy those again. Likewise, I would not buy grafted vines, such as the Cynthiana and Niagara, as we are not good at remembering to cover and uncover the graft unions when the seasons change.
In the South, Muscadine grapes (Vitis rotundifolia) will grow easily, although Vinifera and Labrusca grapes won’t. See Mark Hoffman, Patrick Conner et al, Muscadine Grape Production Guide for the Southeast. Also see the chapter on muscadines in Blake Cothron, The Berry Grower. (My review coming soon) This less publicized grape type deserve more attention, especially in hot, humid areas.
The aromatic, sweet, large round muscadine grapes are resistant to diseases and pests (perhaps thanks partly to their thick skins), have 4-10 grapes per bunch, mature in 90-120 days, and separating from the vine with a dry scar when ripe.
The muscadine industry is a multimillion-dollar industry in the US, but most people don’t know it. Muscadines are probably the first cultivated native grape in the US. There are at least 100 cultivars of muscadines, including Scuppernong, the one people are most likely to have heard of. Some varieties are more suited to wine-making, others for fresh eating. Some are seedless. Individual plants are either male or female, with a few self-fertile cultivars. Planting a ratio of 3 female to 1 self-fertile vine will ensure pollination. Those in areas experiencing winter temperatures below 10F (zone 7b and colder) should choose a relatively cold-hardy variety. Make a trellis before planting time, allowing 16’ (5m) between vines:
Thomas Munson in Texas “. . . became one of the leading experts in native American grape species, and his studies were instrumental in saving the European grape and wine industry from disaster during the late nineteenth century.” Free Munson grape cuttings are available from Grayson College, Texas for growers and breeders (request in the fall). These grapes are easier to grow organically under a wider range of conditions
As with many fruit trees, good air drainage is important. This means an open site where cold air can flow away downslope, and not cause a frost pocket. A site that has some protection from cold winds is valuable. Grapes benefit from soil that absorbs rainfall and lets it drain away when excessive. If your soil is compacted, do some deep cultivation before planting grapes. If necessary install drainage. This important site selection and preparation takes time, so start now! Get a soil test in the fall, and perhaps sow cover crops – see the Cornell publication for ideas.
Preparations for planting
Turn under or smother any cover crops in the rows. Build a strong trellis with cross arms and wires to fit your chosen trellising method. We use the Geneva Double Curtain, a cordon method. It has a single lower wire, fastened to the posts, and a higher wire on each side, fastened to the ends of the arms. If the first vine is trained over the lower wire and onto the east upper wire, say, the next vine will be trained over the lower wire and up to the west upper wire. By alternating, each vine can be planted 10 ft (3m) from its neighbors, but have room on the top wires for cordons (arms) of 10 ft (3m) in each direction, until they meet each other.
Be ready by the early spring shipping date. Ours was 24 March.
Dig 16” (40 cm) deep holes for new vines. Put 4” (10cm) loose topsoil in each hole (no compost). When the vines arrive, unpack them and soak the roots in water for 3-24 hours. For own-rooted plants, pruning roots to 6” (15cm) is possible but not needed. Grafted vines need planting with the graft union 2-3” (5-8cm) above the soil surface, the union temporarily covered with soil until the plant starts to grow.
Spread the roots into loose soil. Cover to 4” (10cm) below grade. Position own-rooted vines at the same depth as it was in the nursery. Tread firmly. Fill the last 4” (10cm) with loose soil (don’t tread). Install label and stake (bamboo). Tie the vine to the stake. (Stakes will be removed after 2 years.) Mulch with cardboard and sawdust. You could prune now to 8-10 buds above the crown spur, and prune more later, or leave for now. Label the vines, make a map and logbook to note flowering and fruiting times, and success of new vines.
Annual Grape Calendar
Compost and re-mulch the vines. Check and repair the drip irrigation. Update maps and logs.
Could take dormant wood cuttings, 6-9” (15-23cm) long, cut at the top 1” (2.5cm) above bud at a slope, heel in, label clearly.
Plant any new vines. Prune existing vines. See notes made the previous year, about replacement arms, etc. Be sure to prune vines well back from young vines, as competition is hard on them. Vines pruned after the buds swell will leaf out a little later, and may avoid late frosts. Tie in well to top wire. Remove any wrong side growth.
Weed the rows, particularly around new vines. Remove stakes from any vines planted two years ago. Mow the aisles. Water if in drought, 1” (2.5cm) per week.
Layer branches of existing vines to fill gaps (very effective gap-filling method). Lay a tip with several buds 2-5” (5-12cm) deep in a trench, cover with 3” (7.5cm) of soil. When new growth starts to appear, fill the trench and pack firmly. Separate the plants the following fall. Layering can also be done in the fall.
Weed. Mow. Water, 1” (2.5cm) per week. Monitor for pests and diseases. Uncover the graft unions of any grafted vines.
New Vines: One week after bloom, remove all fruitlet clusters in the first two years after planting. After hard frosts are past, or once growth starts, prune the new vines to a single stem with 2 or 3 buds above the crown spur. Or if the vine is vigorous, leave two trunks, one for insurance. Remove any suckers growing from the base of the vine.
Mature vines: One week after bloom, thin clusters to one per bud, if the number of clusters exceeds 60 on a mature vine (24 for a 4-year-old, 12 for 3-year-old).
Uncover the graft unions of any grafted vines.
Weed. Mow. Water, 1” (2.5cm) per week. Monitor for pests and diseases.
New vines: Rub off or prune away all side branches growing on main trunks below chosen cordons, and remove any fruit clusters that appear. Tie in new growth.
Once a month – Remove dead wood. Train to wires. Tie in. Take notes. Keep aisles mowed.
Harvest – early August some years, or late August if the first buds got frosted. New vines will not yield for two years, and full bearing capacity will not be reached until 5th or 6th year. The productive life of a vine is 20-30 years.
Weed. Mow. Water, 1” (2.5cm) per week.
Weed. Mow. Water, 1” (2.5cm) per week.
Weed. Water if needed. Last mowing early October. Cover the graft unions of any grafted vines with soil.
Pests and diseases of grapes
Monitor for Black Rot, Botrytis, Downy Mildew, Powdery Mildew, Phomopsis, Anthracnose, and other fungal diseases. Be on the lookout for grape Berry Moth, leafhoppers, scale insects, spider mites and Japanese beetles. Don’t panic about a few Japanese beetles. Grapes (and many other crops) can take a certain amount of defoliation before suffering a loss of yield.
For full technical details, see the Cornell publication mentioned above.
Other small fruits available in August
Asian melons, Asian pears (must ripen on the tree), blackberries, crabapples, fall raspberries, muskmelons, peaches, and plums are still available. Asian melons and muskmelons will only be available if you made a second sowing in May or June!
If you live in Virginia, see https://www.vdacs.virginia.gov/pdf/producechart.pdf
Small fruits that may be starting to ripen include elderberries (mid-Aug to mid-Sept), pawpaws, schisandra (2-3 weeks from the middle of the summer) and watermelons.
Other fruit care in August
Water all fruit crops. Pack away blueberry netting after fruiting. Mow aisles, weed and water all fruit (weed blueberries and raspberries shallowly, so as not to damage roots).
In early August, plant new strawberry plugs at 4 weeks old, or rooted potted runners. Start more plugs if needed.