Can a raised vegetable garden co-exist with nearby fruit trees?

Question

I am putting in new raised beds for a vegetable garden. The beds will be 40cm (16 inches) high. The beds will line the length of a fence and I am planning to put a row of fruit trees (possibly blueberries and passionfruit) between the beds and the fence.

In order to try and prevent the tree roots from colonising the vegetable beds and stealing all the water and nutrients, I am planning on laying porous weed matting underneath the raised beds. My theory is that will keep the tree roots away from the vegetable soil but still allow drainage.

However, I have received strong advice from a family member that this isn't sufficient and that the trees will still suck the vegetable beds dry. Basically I've been told that you can't put fruit trees anywhere near vegetable beds if you want the vegetables to thrive.

Is this correct? Is there any way to make this work? If so I've considered some even more drastic measures such as hammering in sheet metal vertically down the back of the vegetable beds to keep the tree roots from growing in under the beds (they could happily grow the other way into the neighbours place as they don't have anything growing along that fence). Would this work?

Answer 1

I have blueberries growing about 6' away from the edge of my vegetable garden, and I haven't had any problems with roots invading the garden.

I don't know much about passionfruit, but from what I see from a couple of quick searches, it looks like it has a small root system. Blueberries also have a shallow, fairly small root system. It doesn't sound like either plant will invade your beds.

Beware that blueberries want much more acidic soil than most vegetables. With raised beds it probably won't be as much of an issue, but if you have to lower the pH of the soil where the blueberries are planted, and the passionfruit is nearby, you may run into trouble.

You'll definitely want to mulch around the blueberries to conserve moisture. Both the blueberries and the passionfruit want consistent water while they're fruiting; the small, shallow root systems mean they need to be watered frequently, but they don't want to stay waterlogged.

Don't plant the blueberries or passionfruit in a place where they will cast shade on your vegetable beds.

It's hard to say "fruit trees" are good or bad around your raised beds: there's so much variation in plants matching that description that you'd really have to ask a narrower question to get good advice. (I.e. as you've done here by asking about blueberries & passionfruit.)

Answer 2

Agree with bstpierre across the board, but would say more strongly that blueberry isn't a fruit tree, they're bushes, and passionfruit is a vine, a climber which needs support, so again, not a tree. The term fruit 'tree' would be applied to things like pear, apple, peach, plum etc., where the plant forms a woody bole or trunk with the growth held above that. A proper tree would likely cast far too much shade over your veggie beds, but if all you want to grow is passionfruit and blueberry, apart from the latter's requirement for acid conditions, neither should cause too many problems in terms of root invasion.

Answer 3

You don't mention the kind of passionfruit you intend to grow, but I think many varieties are quite rampant, both above and below ground. The species I am very familiar with is Passiflora caerulea, which is not ordinarily grown for its rather insipid, but edible fruit, and I can tell you that a well-established plant will send up abundant root sprouts up to 15-20 feet from the main stand. This in Seattle, a very non-tropical clime. Your constantly moist garden beds will be a magnet for the roots of anything nearby, and a landscape fabric will be no impediment to them.