Grape Growing

Downy mildew (Plasmopara viticola) shows up as pale yellow oil spots on the upper leaf surface with white cottony growth underneath. It needs rain and warm, humid weather to spread — and copper fungicide, not sulfur, is the right tool to stop it. Here’s how to identify it early and manage it before it wrecks your canopy.

White powder on your grape leaves? Learn to identify powdery mildew (Erysiphe necator), understand why it thrives even without rain, and get practical organic and conventional control options — including sulfur, potassium bicarbonate, and canopy management.

Black rot (Guignardia bidwellii) can wipe out your entire grape crop in a wet summer. Learn how to identify the leaf spots and mummified berries, time your fungicide spray window correctly, and use sanitation to keep this disease manageable in a cold-climate vineyard.

You can press grapes for wine at home without any special equipment. A mesh straining bag, clean hands, or a colander and cheesecloth will get the job done for small batches. Here is exactly how to do it, plus when to press whites versus reds.

Racking wine means siphoning off the sediment (lees) into a clean vessel. Rack your first time around SG 1.010, again after fermentation finishes dry, then every 2-3 months during aging. Here’s exactly how to do it safely, when to add SO2, and the mistakes that cost clarity.

A stuck fermentation means yeast has stopped before the wine is dry — SG above 1.000–1.005 instead of the expected 0.990–0.996 finish. Here is how to diagnose it with a hydrometer, fix the common causes (temperature, high alcohol, nutrient deficiency, excess SO2), and restart it using a step-fed yeast starter. Cold-climate and chaptalized musts are especially prone.

Primary fermentation is the fast, vigorous first stage where yeast converts most sugar to alcohol. Secondary is the slow, airlocked finish. Here is exactly what happens in each stage, when to transfer, and what SG numbers to watch.

Campden tablets are pre-measured metabisulfite tablets used to add sulfur dioxide (SO2) to wine. One standard tablet (0.44 g) per US gallon delivers roughly 65 ppm SO2. Pete Lindgren walks you through crush additions, pre-bottling top-ups, equipment sanitation, and why you must wait 24 hours before pitching your yeast.

Potassium metabisulfite (KMS) is your SO2 source for protecting wine from oxidation and spoilage. Learn the exact dosing by weight, the pH caveat for free SO2, how to sanitize equipment, and how KMS compares to Campden tablets — with a clear gram-and-gallon dosage table.

Your grapevine looks dead after winter or a spring frost. Before you rip it out, do the scratch test: green cambium under the bark means it’s alive. Here’s how to check your vine, what winter-kill vs spring frost does, and how to prune and retrain it back to health.

Winterizing grape vines depends on what you’re growing. Cold-hardy hybrids like Frontenac and Marquette survive unprotected in Zone 3-5. Tender vinifera and half-hardy hybrids need root mulching, cane burial, or geotextile fabric. This guide covers every method, when to apply protection, when to remove it, and the fall mistakes that undermine cold hardiness – from a Zone 4 Wisconsin grower compiling 12 years of experience and UMN/Cornell extension research.

Brix stuck at 16-18 and frost is coming? Here is exactly what to do — pick timing, chaptalization, wine style options, and how to prevent it next season. Cold-climate Zone 4/5 guide from a Wisconsin home vineyard.