All they really need is good drainage. They should grow in about anything. Yes, a fast draining, mineral mix is best, but they grow in anything. They will have to be trimmed from time to time, unless they are a tree form of Opuntia. I only see one cactus, and it's an Opuntia genus. I grow one here. I have to trim pads off of it every year. It's like a weed. Growing in native soil only.(clay loam).

Drew,

Thanks for your reply. Both are Opuntia. I will go ahead and plant them as-is then. The soil should have good drainage being next to a berm, and I've been working on improving it for about 5 years now by adding organic matter. The coconut coir is an added bonus.

This is what they look like when I get them:

The soil there looks perfect for them anyway. They sprawl as far as you will let them. Mine has edible fruit, but you know I never harvested it. The thorns are just too hard to remove if they catch you!

Those look like prickly pear cactus that grows wild out here. They will grow in about any type of soil once they are started. If they are the same ones the apples they produce are good to eat and to make jelly out of. Just use gloves to pick them since they are covered with fine little thorns on ther fruit.

The one nice thing is that the fruit is racoon proof. Last year one of the fruits was stolen and eaten in place. The remains of the skin of the fruit were on the ground. I figured I'd have to protect the rest of the fruit but no one ever came back to claim the rest. Poor little coon probably had sore paws for quite a while.

Your amended bed is going to turn back into the original soil as soon as the organic component of the potting mix decomposes and leaches away anyway. The main benefit of digging amendments into soils to be planted with perennial plants is the loosening of the soil by the digging. In future do not amend beds or planting holes except when planting short term plants with tiny root systems such as annual flowers and vegetables. These respond to high levels of organic matter and their growing areas can be re-amended annually or as needed, because part of the year they are not present. Functional special beds can also be made for plants like cacti and alpine plants because in such instances the main ingredients used are mineral materials that do not decompose and disappear. However, even then there can still be problems with small amended areas surrounded by unmodified soils (as when holes, strips or pits are prepared instead of large beds) becoming more like the surrounding soil over time. The easiest and most reliable approach when wanting to provide special areas of different soil is to bring in that soil and dump it on top of the existing soil, plant in the new soil without any blending of the two soils together.

bboy,

The native soil is complete clay and digging only loosens the soil until the next rain comes. I have had good success with amending the soil both by growing green manure crops and by adding coconut coir based mix. The coconut coir has a high amount of fertilizer which is lacking in the native soil. I wasn't a proponent of legalized marijuana but I have enjoyed their leftovers. No plant is given more care than the MJ plants; only the highest grade of potting mix and fertilizers will do. The supply seems to be unlimited as I have been getting a trailer full each week.

I understand where you are coming from but nothing will grow in the clay/river rock mix, which was my soil. Even a pick-ax wouldn't make a dent. The improvement in my soil has been remarkable. The rocks have been sifted out as much as possible and organic matter added to a depth of about a foot so far. Which is why I was worried about putting the cacti in the soil that had more organic matter than the typical cacti would need.

A few years ago I did try simply putting in good soil on top of the clay and not blending but this did not work. The good soil on top dried up almost instantly and the plants could not be kept alive without constant watering. When the soils were mixed they did much better.

Where my house was built it was native prairie that would not sustain anything but the toughest of native grasses. The only way for me to have anything but xeriscape-type plants is to amend the soil. I use less water now than I did, which is actually surprising.

Milehigh, the cacti are fast growing and the organic matter they most definitely will take advantage of it. I agree with both of you but it all depends what you are growing. Blueberries are not vegetables or annuals, yet in most places you most certainly have to amend the soil. Also if you do not mix soils you create a bathtub. The water will stop at the old soil and drown your plants. Always mix amended soil with native soil at the bottom. Even in raised beds.That part is really bad advice not to mix. I know from not mixing and having it happen to me. Mixing them solved the problem completely.