Most spiders are harmless and help the environment by eating disease-spreading insects such as flies and mosquitoes. While it's important to be careful of poisonous spiders, there's no need to fear all spiders. Spiders search for conditions conducive to building a web and obtaining food. If your deck provides these conditions, spiders will build a web and lay eggs. To keep spiders off and away from your deck, you must keep it from becoming a place that's attractive to spiders.
Sweep away existing spider webs and organic debris, such as leaves, nuts and acorns that have fallen from nearby trees. Dispose of these items in a trash bag. Collect any other garbage from your deck and toss it out, too, to avoid attracting spiders.
Hose down corners and crevices on or near your deck where spiders can build webs. Use a strong stream of water to destroy webs you weren't able to get with the broom and dust pan.
Light vanilla-scented candles when you're outside enjoying your deck to repel spiders with the smell.
Fill a small spray bottle with 3 oz. of white vinegar. Pour in 2 tbsp. of vanilla extract. Swirl the bottle around to mix the two ingredients.
Spritz the vanilla and vinegar spray around your deck to repel spiders. Saturate cotton balls and tuck them under or around deck furniture to keep spiders away while you're sitting outside. Replenish the vanilla and vinegar spray every three days.