It’s always a struggle to make sure your arba minim survive through Sukkos. The hardest min, in my opinion, to keep fresh are the aravos. For some reason, these break off easiest, dry up fastest, and just don’t last as long as any of the other minim. So while this doesn’t work for everyone, I figured I’d post how I keep my minim fresh, and it usually does work.
With the esrog, there isn’t much care involved. If your esrog has a pittum, you obviously have to make sure that it doesn’t come off. If you have a very green esrog and would like it to appear more yellow, you should surround your esrog with apples and then cover everything. This should help turn your esrog yellow much faster.
The lulav also doesn’t require much care other than making sure that the top of the lulav is left intact and that the middle leaf is not split.
The aravos and hadassim are usually tied together in one of those bundle baskets. What I do is this: First, I measure a piece of aluminum foil to the length of the entire aravos, hadassim, and basket holder. Then, I put paper towels along this length (usually two are adequate). Next, take a cup of water, put your hand inside, shake off the excess water into the cup, and lightly flick the rest of the water on your hand all along the paper towels. It is important to NOT get the paper towels too wet as this extra moisture can cause mold to grow very quickly on your aravos. The point is to get it very lightly wet. Finally, when not using the 4 minim, carefully wrap the paper towels with the foil so that it is gently wrapped around all the leaves and basket.