1) If I didn't make my own mixes, I would choose Fafard's nursery mix or their 51L blend. We all have our preferences, but I avoid peat-based or compost-based soils because they retain their structure poorly and, I feel, are too water-retentive to assure plants have the opportunity to grow to their genetic potential when used in containers.

2) I'll let others offer suggestions, even though I have a very clear preferences for the media I make myself.

3) Your call, but I wouldn't bother with the test kit. pH changes rapidly in container culture, and you'll end up endlessly chasing your tail and likely doing more harm than good. If you stick with a well-aerated and durable soil you can water copiously to flush the soil of accumulating salts and fertilize frequently, you can grow perfectly healthy and productive plants. In some cases, ignorance (in the classic sense) is bliss.

4) Almost all containerized plants would be perfectly happy on a diet of any 3:1:2 ratio (24-8-16, 12-4-8, 9-3-6) are popular soluble fertilizer %, all are 3:1:2 ratios. (ask if you're confused) They supply nutrients in a ratio very close to that which plants actually use them.

I start my tomatoes out on 24-8-16 or 9-3-6 until there is a good amount of photosynthesizing machinery (foliage) and then reduce the dosage and start adding ProTeKt 0-0-3 to the fertilizer solution. I supply just enough N to keep foliage nice & green. This allows me to supply reduced amounts of N w/o worrying about deficiencies of P or K.

Al

1- Thanks Al. I agree about avoiding peat-Based and compost-Based soils for the same reasons, but what if the mix has a smaller percentage of peat or compost? For instance, Fox Farm Ocean Forest uses a blend of premium earthworm castings, bat guano, fish and crab meal along with composted forest humus, sandy loam, and sphagnum peat moss.

2- Is the mix that you make yourself the same for all container plants? I would appreciate seeing the ratios/ingredients.

3- Good call. So pH testers are more essential for organic methods and/or hydroponics?

4- Interesting. So you don't boost P when it's time to fruit? What is the purpose of boosting K at that time?

1) Every ingredient that you listed for the Fox Farm soil is extremely fine. Since water retention is dependant primarily on particle size, you should expect a medium made of all fine particulates to be extremely water retentive, something I try very hard to avoid in containers.

2) You can read about soils and how durable soils that remain well-aerated long after peat/compost-based soils have collapsed can offer a greater margin for grower error and make things much simpler for the grower if you follow this link.

3) Not necessarily, but if you think about it, what will you do if your pH falls outside the favorable range? Start adding acids and bases to change it? In commercial situations, pH is usually tested frequently and adjusted by injecting a wide variety of chemicals that have elements plants need into the irrigation water. Since pH is affected by temperature, fertility, plant material, moisture level, even time of day (Plants help to control the pH in the rhizosphere to make it easier for them to uptake nutrients. This effect is reduced when plants are undergoing periods of reduced transpiration, which in turn has an effect on pH.)

I'm not saying that because I ignore trying to control pH that you should, but I've never found it necessary to fret about it in any container planting. I might consider the plant prefers acidic conditions and forgo the use of lime and maybe use a urea-based fertilizer to take advantage of the acid reaction, but other than that, I don't worry.

Remember that Media pH is far less important in container media than in mineral soils, and if you're supplying nutrients in soluble form, unless the pH is WAY outside favorable limits, your plant will be able to assimilate the nutrients. You can find considerable discussion about this in Dr C Whitcomb's work, "Plant Production in Containers II".

4) On average, plants use about 6-10x more N than P. Since the P in NPK is not a true measure of P supplied (P is reportted as the % of P2O5 [phosphorous pentaoxide]) you need to use a multiplier of .43 to tell the actual amount of P. In 3:1:2 ratio fertilizers, there is 7x as much N as P, so you actually have a considerable cush in 3:1:2 ratio fertilizers.

Plants use roughly the same amount of nutrients throughout the growth cycle in relation to N, so I'm not sure where the idea they need larger doses of P during flowering/fruiting comes from. Tissue analysis of fruits and blooms show roughly the same levels of P as other plant organs, which meshes nicely with the idea that consistent P levels at approximately 1/6 that of N are entirely adequate throughout the growth cycle.

I actually don't boost K by adding the ProTeKt, I reduce the amount of N, which also must reduce the levels of P and K. Since I can see by my plants that what I said above about P is true (also confirmed in the text cited above, which is essentially the Bible on container production) and P levels remain adequate at reduced application rates of 3:1:2 ratio fertilizers, I only need to be sure plants are getting adequate K. I can do this by incorporating some potash in the soil when I make it in anticipation of the reduced N applications for tomatoes, or simply forgo the increase in TDC by supplying it later as needed by using the ProTeKt.

Al

Hi Robert....

I have had complete success with ALL my plants as pictures can tell you..:-)I will post you a link of just what my grapefruit and orange trees look like in the mix I use and just with a good all around fertilizer..

I use a mix that consists of 5 parts bark, one part peat, and one part perlite..
I also use a mix that is one part bark, one part turface, and one part crushed granite, a gritty very porous mix...

These are not too water retentive, while holding moisture very well, and evenly..Everything a soil mix should do as described above is what my mixes do..

I use use the gittier mix for all my woody plants and ones I plan on leaving in the same containers for a few years, while I use the other for annuals, and plants I plan on keeping in the same pot for a short time..

Fox Farms for me was expensive, and became very water retentive, if not muddy within 3 months of using it, suffocating the roots of many of my expensive plants by holding too much water and from compaction...In fact, I know of a buisness that sells this Fox Farms mix, where the employees there raved of this stuff when they first got it, why I bought into it a couple years ago, only to be disappointed and replace the soil in their containers with a Farfard product..The "nursery" mix, with added perlite in particular..

I never have to boost my "P" to get tons of blossoms and fruit, because I use a fertilizer that gives my plants the perfect ratios in which the plants actually utilize the nutrients perfectly, and happily...

Please excuse my spelling..:-=)

Here is a picture of one of my grapefruit trees in full bloom for the second time this year using just one fertilizer and a capful of vinegar at almost every watering..For mine, there is never a PH issue, unless I stop using vinegar because the PH in my water is very high..

A few other plants in the mixes I use with just one fertilizer...

http://forums2.gardenweb.com/forums/load/houseplt/msg1220293632660.html?46

http://forums.gardenweb.com/forums/load/citrus/msg121920579808.html?5

http://forums.gardenweb.com/forums/load/citrus/msg1109521515384.html?20

http://forums.gardenweb.com/forums/load/citrus/msg1109521515384.html?20

http://forums2.gardenweb.com/forums/load/orchids/msg031742457401.html?9

What ever you decide is best for you, good luck yucatan.:-)

Mike

Here is a link that might be useful: grapefruit pics..

Al,

Thank you for sharing your generous wisdom with me. I really appreciate the conversation.

1- I see. Fafard uses things like pine/fir bark and vermiculite/perlite, so it should have better drainage for container plants as opposed to the finer mix in Fox Farm Ocean Forest.

2- Not sure if I've come across many of the ingredients in your 'long term (especially woody) plantings and houseplants mixture'. My plants are not woody at all, but they are being reared indoors. Would a different/more readily available list of items be acceptable here if I were to build my own mix?

3- I wouldn't add liquid pH up/down to alter pH like the hydroponics growers and pool guys, but adding Lime in the form of crushed eggshells maybe, or Espoma Garden Sulphur would have an effect on pH, correct? If I don't have a fertilizer that supplies things like lime, calcium, magnesium, etc. then I will have to amend the soil with another source of nutrition. The reason I worry about this is because my plants prefer a limey soil. So if my soil is too acidic or loamy, it can have a negative effect on health. In the same manner, if I add too much lime over time and fall out of the recommended pH, it may hurt them too.

4- Thank you for the explanation about the relationship between N & P. I'll take that into consideration.

Mike - That 5-1-1 mixture sounds like something I can easily assemble. I think Al's advice about making sure the particles in the mixture aren't too fine pretty much helped me figure out what to use for container plants.

I like that you have a dedicated grow room. Hopefully I have something like that one day. Thanks for your advice.

1) If you do a little research into Fafard's mixes, you'll see the two soils I recommended from Fafard's were those that had pine bark as the primary fraction and were w/o vermiculite.

2) The peppers would really like it, and it's much easier to remove from the roots at repot time, if you plan of taking advantage of the fact that they are perennials. There are lots of suggestions and threads about substituting this & that for the basic ingredients I list as those I prefer for the gritty mix. Searching the forum for gritty mix will bring up lots of hits. If you're still stuck after a review, let me/us know.

3) Eggshells and elemental sulfur aren't going to have a measurable effect on media pH for container culture unless they are pulverized extremely fine (like talc). Just because your plants seem to prefer a limey soil in in situ situations doesn't mean they will when grown under container culture. It's probably that your plants seem to prefer a higher pH (in situ) because they have trouble limiting their uptake of one (or more) of the micro-nutrients. Supplying a fertilizer with nutrients in a favorable ratio to each other will go a long way toward resolving that issue.

Al