Add 5 drops of pure peppermint oil into the bottom of a garden sprayer.
Pour a big squirt (about 1 tablespoon) of liquid detergent into the garden sprayer with the peppermint oil.
Fill up the rest of the garden sprayer with water. Replace the top on the sprayer and shake to mix.
Mist a light coating of the mixture over the entire garden, concentrating on especially affected areas. The oil and soap mixture will repel any garden spiders but won't harm any plant life.