Just last night I finished writing a piece about why you can't amend a water-retentive medium with coarse material. I wrote it specifically as a rejoinder to the very often repeated advice that adding 1 part of perlite to one or 2 parts of water-retentive medium will somehow yield a 'good' medium. I plan on posting it as a thread because it's important for growers to understand that a half measure won't necessarily improve your lot by half. Punked by Perlite? In any forum that is even marginally related to container growing, you'll find the oft repeated advice that you can make a silk purse from a sow's ear by adding together equal measures of an overly water-retentive potting media and perlite. Many growers erroneously believe that you can start with a medium comprised of fine particulates and miraculously make it better by adding perlite. You can't ..... and I'll explain why. Let our starting point be any soil you're so uncomfortable with you feel it needs 'amending' to increase aeration and drainage. Store shelves from coast to coast offer up hundreds of examples, and fora are full of threads that offer suggestions re how to fix them. If there's a standardize version of the advice, it would have to be, “Mix 1 or 2 parts of it [and it rarely seems to matter what 'it' is] with 1 part of perlite and all will be well; but …… will it? Let's look closer. The answer is – the suggested mixture will not perform any where near as well as you might intuit. Just how is perlite supposed increase aeration when it has no internal porosity? By what miracle does a nonporous particle added to a water-retentive container medium, or a bowl of oatmeal for that matter, increase air porosity? Let's say that you have a gallon of Miracle-Gro potting media - the stuff with the moisture control feature, and to it you add a gallon of perlite. Adding perlite is pretty much the same as adding BBs or marbles. If you screened the fines out of the perlite, you end up with 2 gallons of medium, twice the volume; however the double volume ONLY comes with the amount of aeration that was in the gallon of medium that so needed fixing. We sure didn't get any aeration from the perlite. There is no way to deny that with twice the volume of medium and no more than the volume of air already contained in the original gallon you've actually reduced the per volume total air porosity by 50%; AND, the more perlite you add, the worse it gets. Total porosity continues to diminish as you add perlite until you reach a threshold level of coarse material that occurs at the point where there is no longer enough of the original fine material in the newly created medium to fill all the spaces between the large particles of perlite. That will not occur in most practical applications until the fraction of large perlite particles is in the 75-90% range. If your medium consists of 75-90% perlite, it would be misleading to suggest that you're growing in medium X amended with perlite, when you're growing in perlite amended with medium X. We don't take coffee with our sugar or cream, we take sugar or cream with our coffee. In essence, when you begin with a poor medium based on fine particulates, and start adding coarse material like pine bark, perlite, pumice ....... it gets much worse (from the plant's POV) before it starts to get better. If you add an insufficient volume of coarse material – it stays worse. Perlite's primary benefit lies in the fact that it occupies space that might otherwise be filled with saturated medium. Simply put, media comprised of fine particles with perlite added will hold less water on a per volume basis than the same media without perlite, but the aeration level in the fraction of the medium available for root colonization will be roughly the same with or without perlite. Visualize adding a pint of perlite to a pint of sand, then ask yourself whether or not the perlite helped by adding aeration. The answer is a resounding NO. Did it help with drainage? Only to the degree it decreased the amount of water the medium can hold on a per volume basis, but this is something of a hollow victory. More on that in a subsequent paragraph. If we want to take advantage of what well-aerated media have to offer, we need to understand how to EFFECTIVELY use the materials at our disposal. If you have on hand pine bark in an appropriated size, perlite, and sphagnum peat, you can mix them in such a way that the end result is a highly productive medium for container culture; or, the same ingredients can be combined in ways that render them practically unusable. Growers would be much better served to use water-retentive media like as it is from the bag, in combination with the well-reasoned use of ballast in the bottom of the pot than to make a wreck of their medium by adding an insufficient amount of perlite or other coarse materials. The science applies to total porosity and air porosity at container capacity. When using perlite as an 'amendment' to water retentive media, it would also be better to determine the height of the PWT the soil supports (easy peasy), then mix 4 parts of perlite with 1 part of the medium, and fill the bottom of the pot with that mix to the ht of the PWT. Then top it off with the water-retentive mix - unamended. This would be much more effective than amending the entire volume of medium in the pot with perlite. Remember - perlite's job is to take up space, and the space it occupies cannot be colonized with roots. This is the 'hollow victory' I mentioned in a preceding paragraph. While perlite takes up space that might otherwise be full of saturated soil, and in that reduces the volume of water the soil can hold, it also reduces the volume of soil available for root colonization. Space available to roots to grow is still filled with fine particles, which still hold roughly the same amounts of water they did before the perlite was added. Many things can be used to significant benefit if used judiciously, most of those things can put us at a disadvantage if used capriciously. Understanding the role of perlite, and other ingredients that serve as potential additions to container media are steps toward getting to the point where we're far more likely to be limited by things like climate, light levels, and humidity …… than our own skills. Al

Homey Bird, For extensive discussion on growing tropicals/subtropicals outdoors in the S.F. Bay Area, check out www.cloudforest.com. There were several in-depth discussions on growing mangoes in Northern California in February -- scroll down through the threads until you get back to postings from that month. The short answer is that mangoes have been grown and successfully fruited outdoors in the region -- I saw a mango "tree" (really a large bush) growing outside (but against the wall of a structure) north of Davis in February, and the owner reported that he had harvested about 40 fruits from the plant last season. However, mangoes are certainly (and obviously) not reliable plants in our area. They require a favorable microclimate, and even then they would probably be easily killed in a bad cold snap. They also require very good soil drainage in the winter -- cold, wet soil will probably cause root-rot. (So growing mangoes in a container or raised-bed, or on a mound, is a good idea.) As for bananas: yes, it is possible to fruit bananas outdoors here. Lots of people have done it. But certain specific cultural practices are required, and, even then, success is not guaranteed (even for experienced growers). Again, check out the "Cloudforest" site for lots of discussion on this. (Several participants there are "hardcore" banana-growing hobbyists.) I'm not sure if anybody has succeeded with sugar apples (A. squamosa) outdoors in Northern California. It is probably not worth doing, unless you are a dedicated Annona collector: the cherimoya is much more adapted to the region.

Outdoors will be problematic. If you were in Durban it'd be much better. However, there are agricultural frost cloths you can use to protect plants. These may not prevent leaves being burned by the cold. If the plant gets set back/dies back but survives it will sucker prolifically. You'll end up with a not so tall thicket. This can also happen if they dry out too much or get damage on the trunk. If you could grow it against a north facing wall (masonary or concrete) that retains heat and put a cover over it during cold nights that might work. But I still think you'd get a lot of leaf damage that would look unattractive for long periods. In a pot you could always cut the top off when it gets too tall and then just grow the suckers on until they get too big. Plants don't really adapt, not like people. And people really only adapted by wearing animal furs, lighting fires and living in caves when the weather was bad. Plants aren't at that stage and need us to that sort of thing for them.

Is that the Celadine? Usually I have no tip problems with her. Most years. Some very cold -2007-winters just for one, can mush tips. That front border would a great place to try P.obtusa. I get the feeling that in ground they would be much more likely to hang on leaves longer into the winter..bloom longer too. In ground always beats in a pot. I just don't have room for everything in the few "perfect spots" Or..just too tempting for plant takers. THAT eats up most of my front yard unfortunately.