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deciding between the gritty mix and the 511

Posted by greentoe357 z7b Brooklyn NY (My Page) on
Sat, Jun 15, 13 at 7:08

I am organizing my research and thoughts on the topic. Have some questions, but also hope the table below and the discussion will help others. I just recently tried the 5-1-1 mix and like it very much, but I wonder what I am missing by not using the gritty mix instead or in addition. I grow decorative house plants in pots sized anywhere from yogurt cups to 10' in diameter. I am a beginner, so the mix being fool-proof when it comes to over/under-watering is important.

Check out how I understand these two mixes compare:

I welcome your further thoughts, especially if you see something I missed or if you disagree.

The footnotes are:

(1) I read somewhere that because gritty mix particles are more abrasive, it encourages plants to grow more finer roots (vs 511 mix) as they push their way through the mix. Is it true, and if so, does the gritty mix help plant vitality?

(2) a question on versatility of each of the mix. Ideally, I'd like to deal with one mix only going forward. My apartment is relatively generously-sized, but storing and mixing components for both of the mixes is a bit too much to keep doing on an ongoing basis. Which one of the two mixes would you choose if you were me? What kinds of plants would especially miss the other mix?

This post was edited by greentoe357 on Mon, Jun 17, 13 at 17:20

Follow-Up Postings:

RE: deciding between the gritty mix and the 511 are smart to ponder your situation. Here is what I know: gritty mix is very heavy. it last many, many years without much breakdown. it needs frequent watering. it is good for "woody" plants/trees. 5-1-1 Mix: it is lighter weight. it holds more water. it breaks down after a couple of years. it is quite acidic. hope this helps. goodluck

RE: deciding between the gritty mix and the 511

If you're growing houseplants, which are perennials, gritty mix is probably the best choice. I grow many different kinds of plants in it, from clivias, citrus and ficuses to amaryllis bulbs, spider plants and plumeria. You will need to have a way of allowing a lot of water to drain out of the pots and large pots will be very heavy. My spider plant in a hanging basket weighs more than 30 pounds when it's wet, and I have to take it to the sink to water. You also must fertilize year round. But you can go two or three years without repotting. Some people go much longer. My plants have done better in gritty mix than anything else I've used. And I don't really need to water them very often when they are inside, in spite of what you may have heard.

RE: deciding between the gritty mix and the 511

Looks like gritty mix it is. I was going to try it in any case after having already tried the 5-1-1 mix.

By the way, I noticed my link in the original post was messed up. I just updated it to this:

RE: deciding between the gritty mix and the 511

I was able to read your pro & con list at the new URL. I think you've covered most of the difference between the two mixes. On your two footnotes in the original post, I wish someone else would chime in. I remember Al saying that it was better to use granite grit with its sharp edges than pea gravel that is smooth in the gritty mix, but I don't know how much that has to do with the health of the roots and how much has to do with keeping the mix well aerated.

As for versatility, if you're growing anything but annuals, I think the gritty mix is the most versatile. But that said, I do use the 5-1-1 for younger fast growing perennials that I know I will want to repot at least once a year. I also use the 5-1-1 for some very large plants, like hybrid tea roses and mandevillas in 15-20 gallon pots, because otherwise I would never be able to move them. The 5-1-1 is also cheaper and easier for me to make and store because it weighs less. And, although I have used gritty mix in a couple hanging baskets (orchids and spider plants), it was very difficult for me to move them to the sink to be watered.

The biggest difficulty with both mixes is finding the right pine or fir bark fines. I have been lucky in that I live near Ohio Mulch, which sells Golden Nugget Pine Bark Mini Fines, a perfectly sized bark that is uncomposted and costs less than $2 a cubic foot. I use it for both mixes, and I love it.

RE: deciding between the gritty mix and the 511

Ohiofem, I am totally jelly that you are close to a good bark fines supplier. Which one do you mean here ( )? I used their #302, and the particles were a bit too big.

RE: deciding between the gritty mix and the 511

#312 Golden Nugget Premium Mini Pine Fines

RE: deciding between the gritty mix and the 511

Hi greentoe:

just wanted to thank you for your great post and handy chart! That helped a lot -- a lot of the soil talk here gets very detailed and this was very helpful.

RE: deciding between the gritty mix and the 511

Need2SeeGreen (love the name!), thanks for these kind words! Really nice of you to say that.

I've prepared and used both mixes for several months now and have accumulated some observations, not all of which I've seen here. I've edited the file ( and added a lot to it - check it out. As always, glad to hear if somebody has suggested additions/corrections to the table. Hopefully it'll help others decide between the mixes as well or to otherwise shorten their research.

For me personally, I definitely see now that I can't get away with using just one mix - not with the variety of plants I have and not with how well I want them to do. So, I've learned to live with all the mixes, sieves and ingredients in my NYC apartment. First World problems. :-)

It's not even two mixes. I also have an orchid mix now, a cactus&succulent mix and am slowly learning how to amend gritty and 5-1-1 mixes for different plants or for different pots or for different light/humidity levels or for many other different whatevers - like depending on how I feel about fungus gnats on the particular repotting day. :-) (Peat encourages those little buggers)

It was a pleasure to come back to this thread.

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