This may be a goofy question, but do your buckets have holes in the bottom?

If your containers have good drainage and aren't sitting in the sun, no reason why it wouldn't stay moist for a while. You might want to water well just once a week, see if things dry out more between soakings.

I am not a container gardener, so take this with a dash of salt.

The signs and symptoms of a plant not getting enough water are the same as those for a plant getting too much water. However your "pots" simply may not have enough good drainage. Even if holes were bored through the bottom of the pots bottoms sit on a solid surface they will not drain. If you've not made provision to get these pots up a bit do so and see if that helps, as long as what you set them on does not also block any drain holes there are.

Raising a pot in hopes of it draining better is like standing on a stool so you don't have to raise your hands so high to brush your hair. Gravity works about the same at ground level as it does a foot or two above the ground. In fact, if the container is resting on soil, it's much more likely it would enjoy superior drainage than it would be that drainage is impeded.

As usual, I agree with what Pam (Gardengal) said.

Al

I hate MiracleGro for local political reasons, therefore I've never used this soil since I refuse to support them with my money.

Anyway, I think that product uses some sort of hi-tech anti-dessicant to keep the soil moist. Personally, I'd go the easy route and buy some decent topsoil and mix in some peat moss and perlite and sand, then mulch on top.
(a 10-part recipe would be 5 parts topsoil (or compost), 2 parts peat moss, 2 parts sand, one part perlite. Mix in small batches thoroughly and add to bucket until 3" from top. Plant, water and cover with mulch.) The sand helps to keep potted plant roots loose.

Mixing sand into the soil definitely helps with drainage, so maybe you can simply empty the bucket out, allow the soil to dry out a bit (much easier to thoroughly mix when it crumbles) (lay it out on a plastic sheet 1-2" thick and it'll be ready in an hour or two in the sun), and then get a bag of mason's sand and mix 3 parts sand to 7 parts potting soil and mix thoroughly. I use a Chinese food pint container and add the ingredients to a 5 gallon bucket and mix with a garden fork; mixing small amounts at a time is much easier than all at once.
This will probably solve your problem, since this potting soil sounds like it is very dense and may cause root rot. Just make sure the buckets have good drainage as well.

As for drainage, put 4 - 3/4" holes in the bottom, evenly spaced, and 4 - 1/2" holes on the sides, about 2" from the bottom and then fill the bottom with rocks to keep the drainage holes free of soil blockage. The water will not run out of the holes when you water unless it is bone dry or excessively wet.

Raising a pot off the ground does help. If it is on the patio flat on the concrete and all the holes are on the bottom it will not drain adequately because the concrete will absorb the water and it will sit under the pot and be continuously wicked up into the soil from the damp concrete. If you keep watering it you'll end up with a big muddy mess on the ground.

That is why rocks in the bottom help, and some weed barrier or newspaper above the rocks will keep any water that does drain out of the holes from creating a muddy mess.

I'd personally use some planter dollies with casters so the pots can be moved around. A 5 gallon bucket of wet soil is heavy.

BTW: You are new to gardening and obviously want to harvest some veggies, so you are going to have to add nutrients during the growing season. Personally, I've never grown veggies in pots, but everything I have read states that you must fertilize regularly in pots. The only fertilizer I use is Schultz's (no relation that I know of, although my dad's family did own a nursery back in the 1920's ;) Organic (gel or liquid concentrate) fertilizer. In a pot I'd opt for the weaker solution and apply it every 2 weeks.

Good luck :)

Nat - did you read the thread on container soils? Several of the factors you proposed have been found to be rather detrimental to successful container culture. First, you'd want to avoid using topsoil or compost in a container potting mix. The soil particles are too small and with insufficient pore space (air pockets) which limits aeration and available oxygen and leads to compaction. The best potting soil is highly textural and typically contains NO real soil. And while the compost may initially provide some texture, as it continues to decompose it will produce very similar results -- diminished pore space and compaction. And it too tends to be excessively moisture retentive. What works well in a garden generally produces very poor results in a container - they are two entirely different growing situations with very different conditions and requirements.

Second, adding layer of rocks, gravel or pot shards to the bottom of the container doesn't improve drainage - it only serves to raise up the perched water table so that overly saturated soil is closer to the plant roots. Encountering a vastly different structure (the gravel, etc.) hinders water penetration and acts to impede good drainage rather than encourage it.

And you do want to water each time you irrigate until the water does run freely from the drainage holes - that's the indication that you have thoroughly and adequately moistened the potting medium.

btw, a 5G bucket is not all that heavy :-) I schlepp planted 5G containers and larger around at work every day at a nursery. And I'm getting to be an old lady!!

Read the link and visit the Container Gardening forum - you can't help but learn some very valuable and helpful information that will assist and improve your container gardening activities.

Rather than itemize the many things I disagree with in Nat's post, I'll just point to what Pam said as 'sound' and leave it at that.

Al

Thank you all for your responses. When someone says I should mix other stuff in with the soil or that I should not use MG at all does that mean that it is safe for me to transplant my tomato plants for the 2nd time when they are about 1.5ft high now? I do not want to disturb their roots etc. or cause any unnecessary shock. I think I will probably just end up letting them do whatever they can and then learn from this and provide a better environment for them next year. I actually plan on growing in the ground also next year. I only planted exclusively in containers b/c we are moving soon and thought it would be easier. Thanks for all of the input. Oh one more thing; I read somewhere that I should water until I see that it is coming out of the drain holes, but another thing I read said that would be over watering. What would be the best way to water them based on 1-2 waterings per week? Thanks.

I'm actually not a container gardener at all, in fact I'm not even a flower person, my thing is trees and shrubs (the only flowers I'm successful with are Hellebores, Hostas and Toad Lilies - all grow in the shade).

The reason I suggested that recipe is because I bought a native Red Mulberry seedling a few years ago and I had to plant it in a pot because we were having construction done on our house and the bulldozers went right through where the tree was to go. The little tree grew in that pot for 2 years and a few weeks ago I finally was able to plant it, and to my surprise the roots were perfect! Completely loose, no girdling at all and the rocks at the bottom of the pot fell away as soon as I took the tree out of the pot, and the sand kept the roots very loose as well. It was the easiest planting experience I've ever had - even easier than planting a bare root tree.

As for veggies, I plant all mine in raised beds, so it's different than a container. Daddy09, if your tomatoes are that big already I'd probably leave them alone this season, since tomato roots are actually quite long and fibrous and in such a dense soil they will probably break up when you try to move the plant out of the container. But then again, I've never planted a tomato in a pot.

I do have a question for gardengal48:
I'm making 2 benches from the trunk of my old Spruce that was uprooted during a Nor'Easter a few weeks ago and I want to plant 4 small shrubs, one on each end of each bench. I was thinking of planting Purple Gem Rhododendrons - they grow 2 ft x 2 ft. I think they would look even better in large containers than in the ground (I want to put the benches along my driveway, so I want a bit more of a formal look than a really rustic one). For now, since I'm broke and cannot afford 4 large concrete planters (plastic and ceramic always cracks here) I plan to use 20 gallon heavy duty buckets, doubling them up one inside the other so the outer one is less likely to crack and then I'll paint them to match my house.

My question is what kind of soil mix should I use? I have a big 200 pound square concrete planter with a dwarf Alberta Spruce in it and it has been thriving for years in potting soil. I was thinking that I could use potting soil with some extra peat moss and leaf mould in it for the Rhodis, since they like well-drained acidic soil. But I've never planted a Rhodi in a pot before. I think (I have to check again) that the diameter of the bucket rim is 21"; it is 16" high, but Rhodis cannot be planted deep anyway.

What do you think?

Thanks.