I’m digging some big holes in preparation for next year and I thought a discussion of holes in the ground and the soil prep to fill them would make for an interesting topic. We all have our individual challenges and goals; so there are undoubtably as many approaches to preparing sites as there are soil types and environments. Here’s my situation: Grow type: Semi guerilla grow Latitude: 28.5° Native soil: significant clay and alkaline (7.7pH). Very compacted below 18” Topsoil is very fertile aside from those issues. Water source: Well water that’s alkaline (7.8pH) w/ hardness of 6 grains/gallon. That’s about 100ppm of calcium & magnesium. Goal: To grow some really massive photo plants Rainfall: Minimal but we can (and do) get some torrential downpours occasionally. They can drop 2-4” in a few hours and the water “runs” quickly due to the soil and a decent slope. So, since I want my plants to have every chance to maximize on their growth potential, I’m digging some pretty big holes. They’re about 7’/2m wide and 3’/1m deep. Let me tell you...it’s NOT a fun project doing this in 38°C/100°F temperatures with a shovel and a pick! Lol! Obviously, my native soil won’t work as is. It turns to concrete. So, I’m going to amend it with lots of compost (60%), composted horse and chicken manure, perlite (15%), gypsum & green sand (to break up clay and release nutrients), sulphur and sphagnum peat moss to help acidify the native soil and other nutrient rich amendments. Since my water source is alkaline I thought I’d try to get the soil on the acidic side (pH6) of what cannabis likes, in order to buffer the water and (hopefully) provide a happy growing environment around pH6.8. If this isn’t a solid plan, please let me know. My biggest problem is the clay soil. Sure, I could even completely replace the soil in the hole with something perfectly suited for growing, but that giant hole is basically a bowl without much drainage. Like trying to grow in a bucket without any drain holes. The clay in the native soil prevents good drainage. If we get one of the 10-12cm/4-5” turd floating rains we get from time to time, those holes will be holding an awful lot of water at the bottom. Especially if it runs downhill and finds my holes to drop into. My plants could find themselves suddenly living in a pond! At first, I thought about digging drainage ditches to let water escape; but that’s just TOO much work - digging a 1m deep ditch for 10-12m? NO THANK YOU! Lol. So, I came up with a couple ideas to deal with any heavy rainfalls. The first idea was to build a berm around the hole. Using the dirt I excavated from the bottom of the holes, I built a 34cm/12” high berm around the edge of the hole. This berm will force water to flow around the hole instead of into it. Sure, I’ll catch the rain that falls but not the water that’s running. It also makes my holes even deeper! If I backfill all the way to the top of the berm height, my plants will have about 134cm of soil below them! My next trick/experiment is a pedestal than I left at the bottom of the hole(s). Check out the picture below. Basically, it’s a reverse doughnut shape. The 15cm-20cm pedestal in the middle is that compacted native clay filled soil. My hope is that this compacted soil will serve as a ‘stop’ for any tap root that grows that deep and that the surrounding channel will catch the majority of a major rainfall; keeping the rootball from getting too waterlogged in the event of a major downpour. Do you think the majority of the root ball will remain above that pedestal if a tap root doesn’t go any deeper after hitting the pedestal? The last thing I thought I’d try is setting several lengths of 4” pvc pipes, with drain holes, into the outer rim of the hole. I’m going to make a cutout at the bottom as well, so I can reach down and see if moisture is reaching the bottom of the hole, when we’re at the height of the summer heatwave. If water from the surface irrigation isn’t getting down there I’ll know it and I could even fill the pipes with water to provide moisture (or nutes) to the bottom. Also, I’ll be able to see if a heavy rain has left standing water at the bottom of the holes - letting me know when it’s safe to water again. . Here’s a link to a quick video (Vimeo) of the hole with a brief explanation: They don’t look big in those pictures but they’re the size of 2 man foxholes. I could barely climb out. Lol! I’m all-ears if anyone has suggestions or a critique of my plan. The soil amendment to really another topic and something I’m still playing with. My focus here is the actual hole itself; and how it works for the challenges I have at my grow site. Hopefully it may help someone else with similar soil; even if they want to do it on a smaller scale. Digging these by hand is NO fun; and filling them with high quality soil sure isn’t cheap. Hopefully, it’ll all be worth it, though! How do YOU prep your holes and have you come up with any tricks to compensate for your particular environmental challenges?