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I have a Tulip Prickly Pear cutting that's rooted and has been growing indoors for a month now and I am planning on getting some Eastern Prickly Pear cuttings in a week or so. I have a plan for them in the spring and would like some advice. I want to build a raised grow bed for them, with legs like a table to keep the bed off the ground. I'm doing this so I can control the plants better. I've read that planting them in the ground might not be a good idea because they can grow very fast and are difficult to get rid of. But I need to know how large I need to make the grow bed to accommodate both plant species and to produce healthy fruit. They're both spreading types of Opuntia, meaning they don't grow very tall, they spread out. How deep should the raised grow bed be for their roots to grow well how much space should I give each plant to spread, and what would the best soil mixture be to produce good fruit?

I'm afraid I can't help with your opuntia questions, but I'm sure more knowledgeable people will be able to give better responses if they know where you live and your local climate

esp_imaging wrote:I'm afraid I can't help with your opuntia questions, but I'm sure more knowledgeable people will be able to give better responses if they know where you live and your local climate

I live in Northern Indiana. USDA Zone 5b. Both cactus can survive my area's winters and Eastern Prickly is actually native to the state.

The two Opuntia species that you mention are not "weeds" and will not grow uncontrollably in your area. You will be lucky just to grow them well. I would make the bed raised at least 18" and constructed of suitable well draining substrate. The problem with most Opuntia in your area is keeping them well drained. I see no reason at all for a "table" type of construction to keep them off the ground; sounds lethal even to Opuntia. People growing in your area would be the best source for a suitable "soil mix" but it should be fairly course to drain well. Both Opuntia species you plan to grow can get fairly wide as they grow outward but you can simply prune them back to the size you want each season. I give most of my Opuntia humifusa and O. phaeacantha plants at least 4 ft. of grow space but in a couple of years they may grow into each other and require pruning back.

I'm no expert by any means but I don't see how Opuntia would be hard to get rid of.... They are one of the easier varieties of cacti to grow and they do grow fast from what I understand. But I don't think the they would 'take over' by any means. Even if the plant did get too large, it is nothing a quick trim wouldn't fix.

A. Dean Stock wrote:The problem with most Opuntia in your area is keeping them well drained. I see no reason at all for a "table" type of construction to keep them off the ground; sounds lethal even to Opuntia.

That's the reason why I wanted to make a raised grow bed. I figured that would be the best way to make sure the soil drained well. I plan to make the bottom of the bed out of deck boards, with gaps in between each board, a layer of chicken wire over the boards, layered with gravel, then the soil on top of all that. I also wanted to raise it up so animals are less likely to get into it. Last thing I need is a neighbor's cat going home with glochids in it's back because it thought it'd be a good idea to rub up against a cactus.

A. Dean Stock wrote:I would make the bed raised at least 18" and constructed of suitable well draining substrate. I give most of my Opuntia humifusa and O. phaeacantha plants at least 4 ft. of grow space but in a couple of years they may grow into each other and require pruning back.

So 18 inches of soil depth and 4 foot of growing room? So is that 4ft by 4ft area or 4ft radius from the center of the plant?

jmoney wrote:I'm no expert by any means but I don't see how Opuntia would be hard to get rid of.... They are one of the easier varieties of cacti to grow and they do grow fast from what I understand. But I don't think the they would 'take over' by any means. Even if the plant did get too large, it is nothing a quick trim wouldn't fix.

I've just heard horror stories about people trying to get rid of Eastern Prickly that has grown out of control. I figured if I ever moved, it would be easier to take some cuttings and get rid of the plants if they're in a raised grow bed than if they were in the ground. I wouldn't want to leave them for the next home owner if they don't know anything about the cactus.

If I'm following your plan for a raised bed that is completely off the ground, it seems to me that temps would be much lower at the root zone than a bed raised up from the ground. It might work for some species but many of mine just barely make it through the winter and your winters are more difficult. As for the neighbors cats, I don't think you have to worry about glochids and cats. Dogs maybe but I've found that a good berm of cylindropuntia will keep out most of the neighbors dogs. !!!!

Being completely off the ground would make it not drain as well. Here's a site that explains why, the principle would apply your idea the same as it does to a a flower pot - http://gardening.stackexchange.com/ques ... ater-table" onclick="window.open(this.href);return false;

Putting a free-draining substrate on top of the local soil may also interfere with drainage. The boundary between different soil textures would interfere with water movement. There should be a transition layer which is a mixture of the two media.

greenknight wrote:Being completely off the ground would make it not drain as well. Here's a site that explains why, the principle would apply your idea the same as it does to a a flower pot - http://gardening.stackexchange.com/ques ... ater-table" onclick="window.open(this.href);return false;

Putting a free-draining substrate on top of the local soil may also interfere with drainage. The boundary between different soil textures would interfere with water movement. There should be a transition layer which is a mixture of the two media.

I had no idea something like this existed. Is there really no easy way to dry the perched water table?

For Opuntia it doesn't matter if you get a "perched" water level below the berm substrate because Opuntia roots are shallow. They would seldom penetrate more than a foot so the 18" recommended layer will take care of the root drainage problems. I've done this for many years and have nearly 1000 Opuntia plants in ground with no problems.

A. Dean Stock wrote:For Opuntia it doesn't matter if you get a "perched" water level below the berm substrate because Opuntia roots are shallow. They would seldom penetrate more than a foot so the 18" recommended layer will take care of the root drainage problems. I've done this for many years and have nearly 1000 Opuntia plants in ground with no problems.

Thanks for your advice, A. Dean Stock. I want to go back to your previous bit of advice. With grow space, did you mean 4 ft^2 area with the plant in the middle or 4 ft of growing radius from the center of the plant?

I was thinking of a space 4 feet across with the plant in the middle of it (radius of 2ft.). The depth of the space should be at least 2 ft. but that would be a minimum. I'm not sure how fast the plants will grow for you but here O. phaeacantha would fill that space in 2 years or less. Hopefully they grow a little slower for you. It is a simple matter to cut them back they way you want them and then you have material to trade for more so you have to build even more beds !!!! I started with 3 plants and now have over 1000 so be careful.

Dean