jimster - This is only my first time using blocks, so I'm not the best one to give advice. But so far they seem to be holding together. Like Dave says, your mix shouldn't have large chunks. I tested pro mix mixed with compost, and those blocks held together really well. But I wanted a coir based mix, so I mixed my own. That mix uses about 1/2 coir, 1/4 perlite and 1/4 compost, plus a small mixture of amendments. Those blocks aren't as solid as the pro mix/compost blocks. But so far they're doing ok. I messed up with my seed germination, but I'm keeping some of 'em so I can experiment with the blocks. I'm going to start over on the 12th when the moon's in a better place:) I added a link to an ebook on soil blocks. Here is a link that might be useful: link to ebook on soil blocks

Use the mix you used on your CC, Val, but cut the soil amount with 50% pumice (preferred) or perlite (OK, but not as good as pumice). Don't water for a few days after you repot (when you've taken steps to removed old, dead roots from your plant, and also taking care not to J-root it when you put it in the soil). In just a few years (about 8 up here) you'll have this. This is this year's first flowering (spike began in June).

Hi, Tom After I scanned your article, the first thing I did was follow the link to the OSU research you cited. As I read through it, I didn't see anything different than what is contained in an article I wrote back in '94. The wording and discussion is actually so close to what I wrote, that I tried to find out whether that article was written after mine. I think that initially, adding a small fraction of perlite pumice, Turface, things that you usually consider as drainage material to a large fraction of peat, increases drainage, but only until the peat compacts/nests around the 'drainage' material. Perlite is normally included in commercially packaged soils at less than 10% of the whole. Doubling its presence isn't going to increase drainage or reduce the ht of the PWT, though it will reduce the total volume of water the medium is capable of holding. Illustration: start with 10 parts of fine sand that supports a 4" PWT. Add 1 part of BBs. Does the flow through rate change? How about the ht of the PWT or volume of air in the medium? Technically, on a per volume basis, there is a decrease in the % of air in the sand/BB mix compared to only the sand w/o BBs. All that changes is the 'volume' of water in the PWT. Peat may be slightly different because it's interlocking fibers may not compact to the degree that sand will, but remember that the fiberosity exhibits the same properties whether or not there is drainage material present. If peat compacts when there is no drainage material, it will still compact when there is. In order for drainage material to improve flow-through rates, it has to affect gravitational flow potential. In order to do that, it must great pockets where water molecules can adhere to themselves, increasing their collective mass. These large droplets then depend on cohesion to keep them together as gravity acts to move them down and out of the container. If drainage material can't create 'puddles and channels' within the media, it's not going to be effective. I want to comment on some of the things you mentioned as though we're conversing, so I'll make your offerings bold and my reply will be in default type: Drainage though is a bit of a false goal, or a goal based on an assumption. What we really want is to partially dry out the core of the mix at intervals between watering, which prevents that sour core-rot where roots won't live. My focus has always been on aeration, though I recognize the direct/converse relationship between drainage and aeration. The soils I build and suggest are based on the assurance that they will retain ample volumes of air for extended periods - that they are structurally sound. Of course, drainage automatically comes along for the ride. I don't think I would say "What we really want is to partially dry out the core of the mix at intervals between watering". My view is that there is no 'core' to speak of, because water that is not tightly bound to or in media particles moves down to occupy the PWT, which is actually the bane of most commercially prepared container media. Moisture locked in and on soil particles situated above water in the PWT moves quite freely through media by diffusion, so there is never a saturated 'core', only the PWT if the medium supports one. What we really want, is for the PWT to disappear as fast as possible, so a favorable volume of air can return to the soil ASAP. Roots in soggy media begin to die very quickly, often within a few hours or less at temperatures above 60-65*, so PWTs are a decidedly bad thing. Remember please, that here we are looking at media from the plant's perspective. I acknowledge that a PWT can be a necessity to accommodate our ability or our prioritization in terms of how often we can water, but that doesn't change the fact that media that do not support a PWT and need more frequent watering offer greater opportunity, within the limits of other cultural factors, for plants to grow to their genetic potential. That's an important consideration, because if we knowingly use a soil that supports a PWT because it's more convenient, we are sacrificing some degree of growth and vitality on the altar of that convenience. I try to build my soils to maximize water retention and still have no (or very little) perched water. The cyclic death and regeneration of fine rootage exposed to the anaerobic conditions of media that support PWTs is very expensive from the perspective of energy outlay. Energy that might have gone into blooms, fruit, foliage, or just increasing biomass, must be directed to root regeneration subsequent to each time we dare allow our planting to be irrigated to container capacity. Surely drainage helps and is good generally, but you are assuming it is the only way. I think you can see from my offerings that how I approach container media is more complex than only a single narrow perspective would allow. Al I've seen in your other posts where you refer to capillary action of soils as a negative. I couldn't disagree more. Capillary action is the savior of a soil mix; it's the vehicle that brings wet core water & water from the perched water table you described up to the drying surface, and balances moisture throughout the pot. It eliminates the perched water table. Peat has it and bark doesn't. I've never referred to capillary action as a negative. It just is what it is - the product of adhesion + cohesion - no more friend or foe than gravity or diffusion, which is something you didn't consider. Plants absorb water a molecule at a time, and water readily diffuses in media of large particles due to superior gas exchange. Here again, it's kind of a personal choice. You may prefer a soil with good wicking capabilities, but along with that comes the fact that the better they wick the more perched water they support. I, on the other hand, prefer a soil with good gas exchange (diffusion) and no PWT. The price I'm willing to pay is a strengthened watering can arm. ;o) Bark and peat feel dry to the touch when they reach about 40% moisture content, but plants can still extract water from media particles down to about 30-25%, so 'feels dry' isn't necessarily dry. There's a cush there. I understand what's required for wicking SWCs and how water retention in wick-irrigated media varies from media watered from the top, so we can save that talk for another time. Water starts to perch in containers when the soil particles are something just a little larger than .1". As particle size decreases, the ht of the PWT increases inversely. Whether or not bark holds perched water depends on it's size. Obviously, bark the size of Sugar Pops will hold no perched water, but bark ground to the consistency of peat will. Peat may initially hold more air and water than composted bark, but we all know that compaction is a considerable issue for peat; and conifer bark breaks down at roughly 1/4-1/5 the rate of peat, all cultural influences equal. I point to the fact that I always suggest partially composted or uncomposted bark in the soils I use, in sizes up to 3/8" to ensure no or minimal perched water. The grower can then add finer particulates as he/she sees fit to adjust the water retention of the media. When you start with fine particulates, it's very difficult to amend them to increase drainage/aeration, though as noted above, you CAN add materials like perlite that decrease the volume of water the soil can hold. It just makes more sense to me to approach this from the perspective of building a soil that holds no perched water, but is capable of holding an adequate volume of water in micro-pores, leaving macro-pores largely open, than it is to adopt a soil that, at container capacity, always has a significant fraction of available macroporosity clogged with water. Again, it has much to do with trade offs and what we are willing to do insofar as watering frequency (convenience), but the more highly aerated soil with better gas exchange, which occurs partially because we need to irrigate more frequently, offers better potential. I've grown extensively in both, and if the results weren't significantly better, I'd probably still be growing in a peat or compost-based soil. As always, YMMV. Good talking to you Tom. Al

"Which brings me back around to the OP question... Matty, what kind of soil-less mix are you using? Is it dry, or compressed and you fluff it? Or is it wet to some extent before you use it? That will play a factor with what ratio of compost you use too. And I think your compost is probably dry since you pasteurized and sifted it? This can change the ratio I earlier stated too. I use a majority of dry fluffy soil-less mix, and add in less of wet compost. If you are handling your materials opposite in water content, that ratio would be WAY off. I might suggest something more like a half scoop to a scoop of dry compost to 3-4 scoops of soil-less mix." Beesneeds: I used some really cheap seed and cutting mix from Home Hardware made from "...the finest quality Canadian sphagnum peat moss, composted softwood bark fines, horticultural grade vermiculite and a wetting agent to help absorption of water." The compost that I pasteurized remained wet until after coming out of the oven, so while I'd anticipated that it would be dry and crumbly, it was wet when I measured it 1:1 with the seedling mix. I managed tosort of crumble it into the smallest bits I could, but many were about pea to marble sized. I made an effort to removed bits that seemed to be still a bit to difficult to break into smaller pieces. I added some perlite and vermiculite (maybe a tenth volume of the 1:1 mix) and enough water to dampen and darken. One reason I decided on peat pots was that I figured if the compost was too rich or held onto water too long, these pots would help with aeration. So about half of my seedling got this 1:1 mix, and the other half were put into straight Home Hardware seedling mix. In retrospect, from everything I've read about the need of developing roots for light, fluffy soil, I'm figuring I probably should have used less compost? However, All the seedlings (several types of tomatoes as well as some Hungarian Yellow Peppers) are all growing at the same rate, and seem, to my noobster eyes, to be thriving and developing nicely. The less-than-optimal light that the seedlings received in their first couple of weeks post-sowing started them off leggy, but since being transplanted into 3" pots right up to their cotelydons and being put under the T5 HO 6700K double fixture, they all look healthy.