Is it the good stuff or the cheap stuff? The cheap stuff will do this all of the time, it's actually just awful, and not much good for anything except maybe filling holes in the yard. By cheap stuff, I mean soil-based potting media that isn't amended with peat or perlite -- generally, the kind sold for a lower price that is very heavy for the size of the bag.

If you use a good soilless mix that is made of peat, perlite, and perhaps bark, you shouldn't have this problem. If this is what you're using and it is clumping and hardening, there is probably something seriously wrong with it, like they accidentally added the wrong thing or way too much of something into it at the manufacturing plant.

Personally, the best mix I've found is ProMix brand -- Home Depot stores here in Michigan carry it. OTOH, I just detest Miracle Grow potting mix -- it seems to stay too wet and I've had poor results.

My default is always the cheap stuff causes problems. And that particular issue sounds like too much peat in the mix. IMHO best to mix your own formula & that's one of my spring routines.

Dan

If it gets hard when it is dry and water won't penetrate it, that's the peat moss.

You can not allow peat moss to get all the way dry, or you will have to set the pot in a bucket of water to cover the soil and let it sit there and soak.

I prefer to not use peat moss because it stays too wet too long, and once it gets too dry it is difficult to get water back into it.

Even some of the expensive potting soils contain peat moss, so I don't think the cost of the potting soil is your problem.

Give the soil a good soak and then pay closer attention so it doesn't get completely dried out.

Good advice- I will not let it dry out!

I buy MG potting mix, amend it with perlite and it does just fine. Other cheap potting mixes(not soils) will also do fine mixed with perlite. 2/1 to 50/50 potting mix/perlite depending on the composition of the mix. You need both water retention and good draining in a good mix. 50/50 peat moss/perlite is a cheap and great mix but lacks any nutrients so heavy fertilizing may be needed (depending on the crop) when just getting started. If kept moist it shouldn't clump.

Agree with all of the other posters above.

IMO, the "cheap stuff" works OK if you are you are using it as a component of your own mix. However, your mix recipe may vary depending on the specific bags of "cheap stuff" in the mix. One reason the cheap stuff is cheap is because there is not much consistency between batches/bags. This impacts the recipe. When purchasing, I typically look for already broken bags to see what's inside and if it will likely make good blending stock.

If you get into blending your own potting mix, I find a quarter inch hardware cloth to come in handy for filtering out the larger chunks of "undesirables". I always add peat moss to my mix; the amount needed tends to vary depending on the filtered "cheap stuff". Pearlite or other like components are also great blending components. It may take a few tries to find a mix that gives desirable results.

Some will decide mixing it far too much work and also too unpredictable. For these folks, the best option seems to be to stick with one of the higher priced pre-mixed potting stocks. They are more proven to work, more quality consistent, and a whole lot less work.