Use that soil and forget the top dressing until next spring. That soil already has a bunch of goody goody stuff to last all summer and into the fall. Wish I could find that stuff here.

Oh wow. That looks great. I was just at Home Depot yesterday buying a bag of the ever present Miracle Gro stuff. Wish I had seen this!

"Forest products" and "rice hulls" break down very quickly in my area. I used to buy commercial planting mix suitable for use in larger nursery cans and the hulls broke down in a season. Repotting was necessary after a year. I hopethey last longer for you. Kim

This post was edited by roseseek on Thu, Jun 6, 13 at 0:15

bellegallica, I think both Lowe's and Home Depot carry this brand.

Kim, what else would you recommend? Should I add anything to this mix?

Diane

I wish it wasn't still the longest lasting, but the Moisture Control Miracle Gro Potting Soil remains the best I've found. I use it for large pots all the time and get up to two years from it before more is needed. By that time, I am able to pull the soil ball out of the pot, put fresh below it, replace the soil ball and fill in around it with a bit over the surface. I have gardenias, hydrangeas, mixed pots and roses planted in 18" to 28" pots on clients' patios as well as in the pots in my pot ghetto in the stuff and it's working perfectly in this heat and aridity. It's kept the pots I only see weekly or once or twice a month wet enough to keep things pushing. They're all here in the San Fernando Valley and Santa Clarita Valley where it's arid and hotter.

The usual prices in these parts are $14.97 for the 62 qt. bags (2.5 cu. ft.) at Lowe's and Home Depot. Costco has had 55 qt.(?) or 2 cu. ft. bags for $10, the best price per cubic foot for this type and brand I've found yet. No one else comes close to the $5 per cubic foot price. Kim

As of this week Costco was still carrying the large bags of Moisture Control Miracle Gro.

According to Google, 25 gallons = 100 quarts so I should need approx 1 and 2/3 bags of the 62 qt soil per pot. Am I correct?

I like the idea of moisture control. Do you use any top mulch Kim? Are you still using the Miracle Grow crystals for fertilizing the big pots? I do prefer organic methods. Will it work to top dress in the spring?

Thanks for your font of wisdom Kim. And thanks Tuggy3 for the heads up on Costco.

Diane

Diane, I use the Moisture Control. It's very important if you use it to make sure it is evenly moist before planting.Sometimes the bags dry out at the store and then if you don't make sure all of it is wet there will be dry pockets that never seem to absorb moisture.
I usually mix in a bit of soil conditioner or paver sand to lighten it up a bit as sometimes it can be really dense. Some bands seem to do great in it. Others, not so much.
I use 1/4 composted manure to 2/4 moisture control and the other 1/4 is usually soil conditioner or whatever is around.
I mulch the top inch or so. Moisture Control makes a huge difference. I have tried other potting soils and they dry out too soon.
I've also used ? organic brand potting soil from Big Lots and mixed that 1/2 and 1/2 with the moisture control. I think I've even used the organic GARDEN soil from Big Lots and mixed it with Moisture Control.
If I were going to put it in such big pots I'd do 2/3 Moisture Control and 1/3 of whatever else you'd like to add.
Susan

I can usually fill roughly three, five gallon cans from a two cubic foot bag of soil. I found this conversion

1 cubic foot (ft3) ..7.48 gal = 28.3 liters (l)

Your 25 gallon pots should then require about 2.5 to 3 cubic feet of soil to fill fully depending upon the root ball size of the plants you're putting in them. I wouldn't mix anything with the potting soil as it is formulated with peat and coir to provide the proper drainage and moisture retention. After a season, you can mulch with an organic mulch, but I wouldn't "work it in" as that will damage the feeder roots. If the plants are budded, that will insure a forest of Huey in the pots. Permitting it to break down on the surface, like Nature does, will provide the resources to wash through the roots with rain or other irrigation, just like it does in Nature. I also would not plant other plants in the pots with the roses because they will compete for water and food with the roots.

I would, if possible, plant companion plants in the soil with the tree roots to help shade the pots against the direct, hot sun, reducing the water stress and demands as well as helping to prevent the premature break down of the soil. Increasing the heat and moisture of any organic material, rapidly increases its digestion, composting, deteriorating it faster. Kim

Thanks for your advice Susan and Kim.

Hot sun? Not much Kim. I had the heat on in the house this morning. Our marine cloud layer keeps us chilly.

Diane

Kim and Susan, I thought you might be interested in the reviews of Miracle Grow Moisture Control soil at Amazon. It certainly makes me wary of using it.

Diane

Here is a link that might be useful: Miracle Grow reviews

Fungus gnats can be an issue with any soil which is kept very wet. I've had that issue with a variety of soils at home, but not in any of the pots I've created for clients. I never pot plants for inside the house, period. Everything I've used it for has been outdoor and they have all thrived.

Use it, or not, your choice. You asked for suggestions and this has worked perfectly for me in MANY hanging baskets, small (16 oz cups and four inches) to your size pots in a variety of materials (clay, ceramic, plastic, wood and concrete) both at the "Perma Fog" at the beach as well as in both inland valleys where it gets HOT. All of my pot ghetto is planted in it. All of my miniature roses I use for breeding are grown in it in two to five gallon cans. I grow my rose seedlings in it as well as all of the wrapped cuttings I propagate. I had one issue of a batch of wraps compacting more tightly than any others in it. Those eventually rooted but took significantly longer than normal. All of the photos I've posted here and on my blog of root development for the wraps have been of this exact potting soil.

These are six month old cutting grown plants I propagated this year which are planted in it. I would never use it as a planting mix in the soil as I believe it might remain too wet. I have planted succulents in it but only for outdoor use. I would think it would remain too wet for them indoors where the evaporation rate would be too low, causing them to remain too wet. I selected it initially because I was experiencing issues with pots at home, work and for clients drying out much too quickly. This absorbed and held more water than anything else I've found. Here, pots can dry out quickly. Those I create for clients must remain moist enough to survive their often erratic watering. For quite a few years now, they have. Kim

Kim, I love it! "Erratic Watering"....sounds all too familiar. I'm doing better though!
Dianne, good luck!
Susan

Diane that's great that you've had good luck with that soil brand. I've been afraid to use anything but Black Gold for years.