Post in the linked forum below. A lot more people grow avo's there than this forum, you'll get better input. Here is a link that might be useful: Tropical Fruit Forum

Hi everyone gosalsk - As you've ruled out what I suggested previously, and your plants are growing under trees, could I ask what type of trees they are? I once read on one of the forums that brom's growing beneath She Oak Trees (Allocasuarina verticillataoften) suffered from Crown Rot due to the build up of the fine needle like leaves in the central vase of the plant. It wasn't so much that there were leaves in the vase but due to some sort of toxin given off by the She Oak leaves in particular as they started to rot down. She Oaks are sometimes confused with Bull Oaks (Casuarina littoralis) with the main difference being the needle like leaves which are much coarser on the Bull Oak than the She Oak. See: http://dbellamy.customer.netspace.net.au/bog/native/sheoak.html I don't know if you even grow these trees in your country but I thought it worth mentioning just the same. Like HDD says, poor air circulation can also cause rot and this is most common in over-crowded collections where plants are growing in shade houses in cramped conditions with insufficient air circulation between plants. I guess the same could apply to garden grown plants as well if they were over crowded, however you say that your plants are spread out, but are there other plants that could be crowding them? Another thing that just occurred to me is the mulch; when you say "most with their pots set in mulch under trees". How deep is the mulch compared to the mix level in the pot and is the base of the plant in contact with the mulch. We all know that planting brom's too deeply in the potting mix can create problems and the same can occur if the mulch is too high around the plant. Mulches that contact the lower part of any plant are often the starting points for rot so this all needs to be checked also. All the best, Nev.

Well, avocados are very particular about how their roots receive water, Suzi. Sitting in standing water is sure death for an avocado tree. Which is why Fallbrook and N. San Diego County were so perfect - all planted on slopes. Avocados prefer being planted on a slope so the water will drain away. Their feeder roots prefer water to pass by them. Yes, they need a LOT of water. And the only reason they are still hanging on in our area, is because they really don't grow well anywhere else (as opposed to citrus, another water-hungry commercial crop). And, the fact that people are willing to pay $1.50 to 2.00 a piece for them. But, unlike citrus, which are being successfully grown in other areas of California, due to water prices having climbed to the outrageous amounts we see here in San Diego, Orange, and Los Angeles counties (and to almost the same extend in Riverside and San Bernardino), avocados have not been able to acclimate to the Coachella or Imperial Valleys. So, they're hanging in there, in Fallbrook, still. So, standing water is about the worst thing you can have for avocados, proper drainage is critical to having them survive. Ben, to your questions: Jan Boyce, Reed and Sharwil all sound like excellent avos, but will my limited spacing realistically allow for these cultivars because of their size? - You can keep them pruned down to size using drop-crotch pruning. Those 3 cultivars are worth the pruning, trust me. How close can I plant to the wall? Naïvely, I was thinking I could just plant within a couple feet and just have a bed extending to about 3-3.5 ft from the wall, but thanks to you all, I’m questioning how realistic that is now, considering the size potential for mammoth-sized trees - at least 6 feet. Preferably 10 to 12 feet. I think raising the root ball up in a raised bed will help considering my poorly-draining soil. Since I don’t have a slope, I plan to put in a French drain at bottom to hopefully help with drainage. - Yes, Yes, Yes! Thing BIG mound or berm. Excellent option. And, a french drain below the mounds, a couple of feet down, sloping away from the trees, hopefully towards your front yard (and out to the street if you don't need the water elsewhere in your yard). I would also see what's happening with your next door neighbor's drainage. Is it draining over to your yard? Are you dealing with your and THEIR water? If so, make your neighbor fix their drainage issues. That's really a big no-no, as some else's water draining over into your yard could affect your home's foundation and that is grounds for a lawsuit. I would make your mound or berm at least 1 to 2 feet high (if you can make it 3' high, that would be superb) and 3 to 5 feet around (or, just continue the berm straight across for all 3 trees). Put down at least 20 pounds of gypsum spread around the base of each of the trees, plant and then mulch the area with 6 inches of woody mulch keeping the material about 6-8 inches away from the tree trunk. Of course, the french drain system should be below the mounds, about a foot or two down in the ground. You can also spread gypsum down into your french drain system as well. That gypsum application will really, really make a difference in the drainage of your soil. And, lastly, it wouldn't hurt to apply one application of Agri-Fos at planting, then again in 1 month. Apply a 3rd application of Agri-Fos in Feb or March, and then once a year in Feb or March thereafter, just to make sure you don't end up with Phytophthora issues due to water built up in the soil. You can also apply it to your citrus for the same reasons. An ounce of prevention can save you a pound of cure (and agony) later on. If avocado roots are shallow, how deep do they typically go? How much spacing tree to tree, at minimum, should I allow? - the feeder roots are very, very shallow. Most exist within the top 6" of your top soil (as compared to citrus feeder roots, which exist in the top 12 to 18" inches of your soil, and they're considered shallow rooted, so you can see how very shallow avocado feeder roots are). That's why their leaf drop is so critical to their survival. They literally make their own mulch, and if removed, it will affect the health of your trees (and even kill them, eventually, believe it or not.) Their feeder roots will grow into their leaf mulch/mold. They have very sensitive root systems, and do not like to be transplanted after being established. But, they can send down fairly deep anchor or tap roots. And being between the 2 houses should getting enough sunlight be a concern? - It can be. I have an inherited (was planted here before we bought the house and moved in) that was planted in the worst possible spot on my entire acre for an avocado - in nearly full shade, at the lowest part of my yard where the large part of my yard drains down to via two large swale systems. It is amazing it is still alive. I would have transplanted it, but it was too large and established. I figured I'd kill it for sure if I tried. It has produced 3 avocados for me since we moved in, in 2009. As opposed to my Lamb Hass, in the ideal location (full sun, on a nice slope), that produced about 30 avos this season (3rd season), and will have over 100 this next year. So, sun is pretty important. If you're sure they will get at least 6 hours of sun, I think they'll be okay. They might grow slower, and produce a little less, but, considering avocado trees can be prolific producers, that may not be a bad thing with 3 avos, lol! I would plant the Reed in the middle, as it is the most columnar in growth habit, and then simply keep them all down to about 15' and you're good! Patty S.

It is nice to see kimmsr confirming overwatering is a very common problem. Obviously several people here have a lot to learn. If you search for overwatering on Swedish sites using the Swedish word (övervattning) you will get lots of hits, one being this official page on the probably biggest gardening site, with a top 7 list of reasons why newly bought plants soon wilt at home. Overwatering is number 1 on the list. But I'm not sure when root rot kicks in, you get a few other symptoms before that, and you can also get stem rot, which is probably even worse for the plant, so I should add that to the topic (any kind of rot or permanen damage). Since more than one person here seems so convinced overwatering (meaning: keeping the soil very wet for many days) is not a common problem, I took a look at soil contents in Sweden and the US. Houseplant soils in Sweden Here you have a major Swedish soil company, who state plainly the contents for all their houseplant soils: Sowing soil, for seeds (sÃÂ¥jord): 90% peat, 10% fine sand Elite Potting Soil (Elit Blomjord): 87% peat, 7% sand, 6% leca 2-6mm Potting Soil (blomjord): 90% peat, 5% sand, 5% barch mulch Potting soil with leca (blomjord med leca): 87% peat, 8% leca 2-6mm 5% sand 0-6mm Orchid soil (Orkidéjord): 70% pine bark, 30% peat These are relatively expensive soils. Cheaper brands are very similar but often up to 95% peat. Note: Leca balls are like rugged stones, same use as perlite. "Sand" normally means fine sand in Sweden, we have a separate word (grus) for gravel/grit/coarse sand. Most people who know what they are doing probably buy leca or gravel separately and add as much as they see fit. As you can see, if you visit a store which have all 5 types (most don't) the one with leca has only 8% leca. Not everybody sells the small leca balls though, most stores have only the bigger 8-12mm. Plants bought here come in these mixes so you have to live with it no matter if you like it or not. But 2/3 potting mix and 1/3 gravel has been confirmed now by 3 experienced persons here to be well drained and suitable for palms in general, one of them sells palm trees for a living. Houseplant soils in the US Home Depot is a major chain right? They seem to have only one soil for ordinary plants, the all-purpose mix. Sphagnum peat moss I think is the same I call peat above (usually half "light" and half "dark" here). But then I don't understand the difference between "peat" and "sphagnum peat moss" in the contents or the all-purpose mix. It could be 80% peat afaikt, not 87-95% as in Swedish mixes but not very far from it. "Sand" hopefully means coarse sand in the US. If so, it has 20% "grit" (including sand, perlite etc) compared to the 6-8% leca (and 5-7% sand which may well be to a great extent fine sand) so there's a difference, not big but probably significant (in my world 10% grit is not much, 25-30% is plenty, 20% is almost there). The seed starting...