Put big-ticket items on your buy-in-September list. With the first cool winds of fall come sales on major consumer products. The Labor Day holiday presents the best discounts on select items until Black Friday rolls around in November. Here are the September deals to look for:

Mattresses, Bed, and Bath Supplies. Labor Day sales kick off the action early in the month. This is one of those holidays when mattress retailers offer deep discounts on piled-up inventory. You may also find some better-than-normal deals on bed and bath supplies, such as linens and towels, during Labor Day sales and throughout the month.

Planes, Bikes, and Automobiles. Looking for a cheap mode of transportation? September ranks high when it comes to snagging low prices on holiday airfare, a bicycle, or a car. Life Hacker recommends buying plane tickets about eight weeks prior to your travel date. September puts you a bit more than eight weeks out from Thanksgiving, so start looking for cheap tickets now if you plan to travel for the holiday. Check out Cheapism's list of cheap airlines and our report on airline fees to learn about prices, policies, and perks.

If you aren't set on next year's car models, the time to buy one from the 2013 lineup is September and even October. Last year's models are taking up space on dealers' lots and they need to move these cars out fast to make room for the 2014 vehicles that will be arriving in short order. Cheap hybrid cars are no exception.

New-model bikes are released every September so this is a good month to find deals on older model bikes. As with cars, retailers are looking to open up space for the new wheels and are offering unbeatable discounts on current inventory.

Appliances. September is also a good month to buy large appliances (think washer, dryer, refrigerator, stove). New 2014 models will be hitting showrooms soon so retailers are eager to sell off older stock. Although still new and perfectly functional, they aren't of the moment -- a small sacrifice for a better deal.

Plants. Real Simple reports that summer plants, trees, and shrubs can be had for dirt-cheap prices this month because garden centers are stocking up on fall and holiday plants. With cool temperatures on the way, September is the right moment to fill out your landscape.

Summer Gear and Lawn Mowers. Where August saw sales on lawn mowers, BBQ grills, swimsuits, and other summer gear, September will see those discounts deepen. But beware -- the selection will be thinning so shop early and snatch up a deal when you see it, otherwise someone else will. Yard décor and outdoor furniture sales will begin heating up this month as well. Take advantage now or wait for even deeper discounts in October, albeit on a smaller selection.

Old iPhone Models. There have been recent rumblings about yet another new (and cheaper) iPhone on the way, reinforced by last September's announcement about the iPhone 5. If the newest iPhone is previewed this month, prices on older versions will start falling fast. Some savvy consumers may prepare for the big day by selling their current iPhone, so add this to your list of what to buy in September. uSell.com examined the market following the iPhone 5 launch and found that if consumers lock in the sale of their iPhone 5 now -- prior to the new product launch -- they could earn up to $72 more on the iPhone 5, $46 more on the iPhone 4S, and $29 more on the iPhone 4 than by waiting to sell after the fact.

Denim and Back-to-School Supplies. Now that most students have already returned to school, back-to-school supplies will be at an all-time low, especially if retailers have a surplus of a particular item. Selection may not be what it was in August, but you won't beat the prices by buying in September.

Denim is a popular back-to-school item on student wish lists and come September, denim sales will break out. You may want to wait, however. Discounts and coupons will only increase next month and in the weeks leading up to Christmas.

Seasonal Produce. This is your last chance to enjoy low prices on summer produce such as corn, peaches, plums, nectarines, peppers, mangoes, green beans, lettuce, and tomatoes. And if you want to brighten up your home, summer flowers will be at rock-bottom prices this month, as well. September will also see the first of fall produce to hit the grocery stores. Look for cheap prices on apples, berries, beets, cantaloupes, cauliflower, eggplants, grapes, honeydew melon, pears, squash, mushrooms, sweet potatoes, figs, and dark leafy vegetables like spinach

How To: What to Buy in September