40th Birthday Outdoor Garden Party Ideas. 20K shares. Fun and easy 40th Birthday Party Ideas for a beautiful outdoor party. Creative ideas that anyone can do for a 40th Birthday Party! I hope you love these fun 40th Birthday Party Ideas! Birthday parties are my favorite thing to plan. I normally donâ€™t plan big lavish parties for myself, but 40th Birthday Party Ideas | Backyard Table Decorating Ideas Please note: You are currently browsing img 1 piece glitter happy birthday gold letters hanging that is 800x800px in size. This image is listed in garden birthday party decorations category. 40th Birthday Party Ideas Backyard Table Decorating Ideas, 800x800 in 172.19 KB.