Most sources recommend watering when the top 1" of soil is dry.

Does "dry" actually mean DRY? Like when the potting mix breaks apart into powder when you rub it?

Because I noticed it takes a fairly short amount of time for it go to from wet to damp, but damp to bone dry takes forever. Even in a streak of 90 degree days, it seems like I'm waiting a concerning amount of days between waterings, waiting for the plants to dry out.

AlexKr
Watering frequency depends on a few things. For an average-sized hanging basket in full sun in 90-degree weather, I'd probably water it daily because it is exposed to the air on all sides and dries out very fast. Possibly every other day. Factors that affect that are how densely it's planted, whether it's in sun or shade and the nature of the potting soil. If you wait until the soil is bone dry it will become hydrophobic and water will run down the sides but won't saturate the interior. More hanging baskets fail from drying out than over watering.

Planters and pots are a little different. Assuming they have drainage holes, you should water until water until water runs out the bottom and then the 1" rule is pretty safe but not an absolute. Again, location, temperature and plant size affect watering frequency, as does the type of plant (whether it prefers moist or dry soil). One reason your soil is staying wet could be because the container is too big for the plant(s) and their roots aren't developed enough to fill the container and use the water quickly. In that case, do be conservative until the plant matures or you risk drowning the roots. And certainly water if the plants look distressed or wilted.

As the season progresses, you'll get a sense of how frequently to water based on how the plants respond.

Hi & welcome!

Well said, Zoë.

About hanging baskets, most of the ones I see have a drain hole, but it is not at the bottom of the pot but recessed about ½" above the bottom of the pot. This allows ½" of water to be trapped in there. Some plants like this, but some rot. Rotting plants look wilted & thirsty, which makes us think they need to have more water added. But in the case of trapped water, some just need relief from that excess water. If you have this type of pot, you can snip a hole with pruning shears to allow that excess water to escape.

Picking up a hanging pot is a sure way to feel if it is more lightweight than it was right after being watered. If you can tell the difference, it's time to add more water.

Boy, does watering depend on so many things! Can't deny that what Zoe and Tiffany say are right! I would like to add that the ambient level of humidity in the air also has an effect on when to water. I've noticed my watering is less on days in the 90s when the relative humidity is 50% or above. The drier the air gets in the summertime, the more frequentlyI water. The type of soil also plays a big role here. Almost all potting soils sold are essentially "soilless"; they don't have any actual dirt in them, just ingredients such as peat, vermiculite, shredded wood chips, etc. Some are designed to be moisture retentive, they say so right on the package. Other mixes are made for cacti and succulents, which need a fast draining mix. You need to consider the water requirements of any particular plant and use the right potting soil mix when you plant it.