I have just started my vegetable container garden and i have about 5 pots full of garden soil and Miracle gro in them. As i live in Florida it rains. I have noticed that the pots are not draining as much as i would like. I drilled extra holes and now i am afraid i have the wrong soil. Anyway, what is everyone using for there vegetable soil and drainage.
Thanks,
Michelle
New to vegetable container gardening, question about soil.
Try reading this, if you have a mind to wade through it:
http://davesgarden.com/forums/t/527353/
Al
I grow everything in containers and I use Super Soil Potting Mix. Miracle Grow is similar but I think there's some fertilizer added to it. You can make your own potting mix (there are different recipes) but I find it easier to buy it pre-mixed.
Large holes are important for drainage. For very large containers (18+ gallons or more than 12 inches of soil) I add a 2 inch layer of large bark on the bottom before putting in the soil. Some people put large styrofoam peanuts instead to keep the whole thing light.
i use miracle grow in all my containers. i use 5 gallon size only i put 4
25 cent size holes about 2 inches from the bottom of the container. i feel that this way there will always be some water at the bottom of the container. it works for me.
WOW. First Thank you everyone. And to Al that was everything I needed to know and more. I have one question for you Al. I cant find the pine bark. Is there anything i can use instead. And how long does this mixture last, meaning will i have to repot often? I am a newbie at all of this so forgive me if this is silly.
Thanks again,
Michelle
First, as long as the drain hole isn't blocked, there is no advantage to multiple holes in a container bottom. The difference in time it takes for a container to drain with 1 vs 10 holes is small, and of no significance. All containers should have their drainage holes at the bottom of a container, not on the sides.
The bark is out there. It is usually from southern yellow pine & in your area likely processed by Southland Corp. It's worth looking for. It often is sold as "soil conditioner". Look for the partially composted stuff or if unavailable, buy the small bark (about 3/8 ") and use it as is, or compost it for 6-9 months before using. It is much superior to any peat-based soil and will retain its structure far longer. The bark is rich in a lipid called suberin. It helps prevent micro-organisms from cleaving hydrocarbon chains & breaking down the pieces.
The picture I provided shows the composted stuff at the top. The stuff on the left is the next best choice, but will work better if composted awhile before using.
Al
Yes, but don't forget to put a 4" layer of River Rock on the bottom of your containers for good drainage or you will invite root rot.
Sorry to disagree, but drainage layers in container bottoms are ineffective at helping remove unwanted water from containers. They serve only to raise the perched water table higher in the container, which more often than not is counter-productive and the cause of rotted roots, especially in new plantings where roots have not colonized the entire container and in over-potted plants.
Al
Al --- I have grown in plastic and clay containers. When first I started, I did not use rocks as a base and my plants were always skimpy and some produced minimal amount of tomatos if any at all. The root system was small and rotting. It was not until a gardening program caught my attention and it was about container gardening that I learned about drainage and sure enough the following season my plants were beautiful and healthy. I had pictures of before and after but since have moved and some things are still in boxes in storage. Perhaps it works best for me because of our humidity. If you lived in a drier state you may be able to garden your way but it does not work here. Earthboxes work on a similiar principle and their production can not be denied. Also one other fact is that clay pots are far better than plastic as plastic can not breathe and clay will allow excess water to evaporate thru it's pores. Plastic pots will easily blow over when the plant is mature as the plant acts as a sail. I've lost many plants this way because I thought I was saving money. Large 20" clay pots work best and last forever.
Tplant
Please imagine that you are growing in the same medium that gave you problems initially. Obviously, the soil retained too much water or your watering habits weren't appropriate for the soil you were using. Every container soil has a point where the pull of gravity on the water in the container is equalized by capillarity of the soil, at which point the container stops draining (in the nursery trade, this is termed "container capacity"). When this occurs, there is a layer of saturated soil at the container bottom, the perched water table (PWT), in which all available spaces are filled with water that cannot drain. Now comes along a container gardener that thinks adding a layer of gravel or packing peanuts will improve drainage. Not so.
Let's say that there is a 3 inch layer of saturated soil at the container bottom. If you add your 4 inches of gravel, you have 4 inches of gravel topped by 3 inches of soggy soil and finally, above that, soil that is conducive to good root health. If you are growing in a 12 inch container and leave 1 inch of headspace, that means that only 4 inches of the soil will support root growth until the plant has used the water in the PWT or it evaporates. This is all dictated by the physics of water movement in soils, so where you live doesn't have any effect on the science.
It's much more beneficial to choose a well aerated soil and fill the container from top to bottom with that soil. If you water correctly, this gives better water holding ability, better nutrient retention (gravel/peanuts = none), and a maximum volume of soil for roots to colonize. If you water incorrectly (too much) the perched water table is at the bottom of the container and still leaves a higher % of soil at the top of the container with good aeration.
I left a link to something I wrote in a reply up-thread somewhere. It explains the science of water movement in a container & gets into what makes a good soil for containers. If you never lose sight of the fact that proper aeration/drainage is the most important consideration in container culture, I can promise you'll find growing much easier.
Al
I put the rocks in first - then the potting mix. I do not put in the soil and then rocks. I have posted many of my results and never had problems with my large 20" clay pots and Miracle Gro potting mix. Guess I'm just lucky!
Growing in containers has little to do with luck, unless you are counting on rain to water your plants. ;o)
To clarify what I wrote above: Let's say that there is a 3 inch layer of saturated soil at the container bottom. If you add your 4 inches of gravel (to the container bottom), you have 4 inches of gravel topped by 3 inches of soggy soil and finally, above that, soil that is conducive to good root health. If you are growing in a 12 inch container and leave 1 inch of head-space, that means that only 4 inches of the soil will support root growth until the plant has used the water in the PWT or it evaporates.
Growing in unglazed clay containers has the added benefit of allowing gas exchange through container walls. This helps speed evaporation of the water in PWT's and allows needed air to roots faster, a good thing. Fine rootage begins dying within hours of being deprived of O2. When soil is soggy fine roots die. When the water in the soggy soil is depleted and air returns, roots begin regenerating. This seesaw process is taxing to plants, using energy for root regeneration that might have been used to produce additional foliage or blooms. It should be easy to see how this slows plant development.
Illustration: Hold a saturated sponge in a position so the largest surfaces are at the top and bottom until it stops draining. The sponge will still be largely saturated and represents the soggy soil perfectly. Now, place the sponge on top of gravel or packing peanuts. Does it drain? Of course not. So why would we expect soil to drain when we treat it in similar fashion? When we add soil above a "drainage layer", we simply take the saturated soil that would normally occupy the container bottom and move it higher in the pot so it occupies a position above the "drainage material".
With careful watering practice, you can get plants to grow well under these conditions, but they will always be at a disadvantage. In the early stages, soon after the planting is made and roots are underdeveloped, they will be immersed in the most saturated soil in the container. Later, as roots eventually colonize the container, the planting will lack the water and nutrient retention a mature planting requires.
Al