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Hop Dry Matter Determination Method

This method is used to determine the moisture levels of the hops so that they can be harvested at the most optimal time.

Supplies Needed

Dehydrator

Scales capable of weighing grams

SAMPLING

Gather at least ten different side arms from the yard being sampled. The arms should all be taken at the sixteen-foot level, or two feet below the trellis wire. Walk through the yard on the diagonal, sampling occasionally in a random manner. Frequency of sampling as you walk through the yard will depend on the size of the yard being sampled. The sample area should reflect the character of the entire yard, especially if major variances are observed.

Sampling should be done after the morning dew has dried, after any fog has lifted, after irrigation water or moisture due to rainfall has dried from the cones on the vines. Samples should be kept free of any additional dirt or moisture and stored in a cool place until tested.

TESTING

Pick all the cones off the side arms from the above sample into a bucket. Hand mix all cones in the bucket and randomly remove 100 cones. Place the cones in a container that has been already weighed to determine the tare weight of the container. Then weigh sample with the one hundred cones and record weight as GREEN WEIGHT in grams to the nearest two decimal places.

Place the entire sample into a dehydrator and leave it run overnight (140° -150° F), drying the sample to zero percent moisture. The next morning turn off dehydrator when you are ready to weigh the dry sample. Using the same container that you weighed the green hops in, weigh the dry hops and record the DRY WEIGHT in grams. Please note that more than one sample can be ran in the dehydrator if properly labeled.

To calculate the formulas, subtract tare weight from both the GREEN and DRY weights. Then calculate percent dry matter for the sample by dividing the net DRY Weight into the net GREEN Weight.

To predict the optimal date of harvest compare your variety and dry matter percentage to the chart below. Please keep in mind that these numbers can be ± 1% due to the many variables. The harvest date also depends upon the weather and the crop condition. For example, if the weather is extremely hot it can mature faster or you may want to harvest early if you have a spider mite infestation.

    Fuggle21% 1% increase each four days
    Mt. Hood23% 1% increase each six days
    Nugget23% 1% increase each four days
    Galena22% 1% increase each six days
    Tettnanger21% 1% increase each four days
    Willamette20% 1% increase each seven days
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