Try the vegetable garden forum.

I don't set much store by 'companion planting' other than grouping crops by their requirements and their season. My vegetables all have flowers growing amongst them for the benefit of wildlife. I don't think they do much for the vegetables themselves. Onions are supposedly good against carrot fly but that's one of the few proven combos I believe.

Marigolds are supposed to repel pests and look nice among the veggies.

There is little scientific evidence that marigolds repel pests other than certain species which repel root nematodes. And they only do that if planted well before the vegetables are put in the ground.

https://piedmontmastergardeners.org/article/magical-repelling-powers-of-marigolds-myth-or-fact/

While onions may be beneficial against carrot fly, onions are now subject to the allium leaf borer, a real PITA to control.

i think the most important thing is to think ahead about the heights so you arent blocking sunlight. Asparagus , for example, remains standing tall for months after it is harvested.

In my Zone 6b garden, I've found that tomatoes and basil thrive together, enhancing flavor and deterring pests like tomato hornworms. Planting carrots with onions has helped reduce carrot fly issues. For interplanting flowers, marigolds are excellent among vegetables for their pest-repelling properties, particularly nematodes. Nasturtiums also work well as a trap crop for aphids. I’ve experienced improved pollination and a burst of color by adding zinnias. Keep experimenting, as local conditions can vary, but these combinations have consistently worked for me!

The above post comprises many of the usual unsubstantiated and frequently regurgitated companion planting claims. Having looked at the posters other efforts I suspect AI spam. "Tomatoes and basil thrive together, enhancing flavor and deterring pests like tomato hornworms." There is absolutely no scientific evidence for this often repeated but unsubstantiated claim. They may well thrive together but only because they like similar conditions. They have no effect whatsoever on each other, and certainly not on flavour. Nasturtiums don't act as a trap crop. They attract aphids, true, but this just means there are far more aphids in the area than there would otherwise be. And how on earth can one tell if pollination has 'improved' if you have no control?

Suggested reading: https://www.gardenmyths.com/companion-planting-truth-myth/

You can buy ladybugs and release them into the garden for natural aphids control. Diluted milk works for powdery mildew. There is some natural snail control you can diy.

Under the right conditions, there really are no rules as long the veggies get at least 6 hours of sun a day.

Keep the taller plants at the rear as suggested to not block those in front. So sunflowers and stakes in back for climbing beans and peas, then tomatoes in front of them with tomato cages. Then taller leafy veggies like rhubarb, peppers, kale. Lowest in front like strawberries, squash cucumbers.

Edible flowers like nastursiums are so pretty to fill in.

Rhubarb, being perennial, needs a permanent position. It isn't really suitable for planting together with annual or biennial crops.

Regarding tall plants blocking sun this depends very much on the microclimate of the garden. In hot dry places some crops, such as lettuce, can benefit from some shade.

Releasing ladybugs in the open garden is not particularly effective. They can fly. And they do. Bringing in larvae is more successful. But if there are none in the garden naturally it's likely conditions are not very conducive.

They won't fly away if there are aphids...it's their main food source. Nothing wrong with releasing ladybugs...set them free!

I'm a fan of companion planting. Only now-a-days, most of the more accurate things get moved on to "integrated pest management" and the like. The stuff that's mostly ole wives tales gets left under the title of companion planting.

No, basil does not actually make your tomatoes taste sweeter, as in changing the brix. But it can attract beneficial insects and can repel or disorientate some bad insects. Dill is a good companion IMO, since it attracts brachnoid wasps- they prey on tomato hornworms. Basil might work, but I know and have seen dill work. A healthier plant that isn't being bugged is likely to produce better tasting fruits than a stressed plant.

Planting in flowers, particularly nectar rich ones, can attract pollenators to your veggies. But don't count on honeybees wanting to pollenate your tomatoes- tomatoes don't produce nectar.

Throwing three fish in the planting hole isn't a thing anymore- we know the magic does not work. But we also know that calcium is good for helping blossom end rot, and fish fertilizer is found on many shelves now.

Family members can be poor companions. Like nightshades have similar feeding needs and can host some of the same bad insects and disease issues. It's not that they "don't like each other" like gardeners long ago thought.

Something like a three sisters garden is an excellent companion trio. Not only for the structural aspects and some critter deterring. Now we know enough plant science to understand how beans work with nitrogen, squash blossoms bring pollinators needed to pollenate corn, ect.

There is some good science that has come out of the old wives tales. Some of it is total crap, true. But we have mostly let go of the magic and are figuring out the science of it now. Akin to how alchemy grew into chemistry, and hedgerow witchery turned into medicine.

Again, I'm a fan of it. But I very often question why and how these plants are supposed to be good or poor companions rather than relying on a handy chart or the like. If there is a good reason(s), then great. If there isn't, then maybe don't believe that tale so much. If it seems iffy, but don't seem to do any harm- maybe try it for a season or two and have personal observations on the tale.

So questions come... what veggies are you wanting to grow? Tell us that, and we may be able to tell you more. Since this is under landscaping and accessable gardening, are you looking to buld in some harscaping with raised beds or the like? If so, raised bed gardening can be a bit different than in ground gardening.

Setting them free is fine but purchased ladybugs DO NOT stay in the garden! It has been proven that less than 5% will remain present after 48 hours. It has to do with them being harvested from another part of the country, forced into a prolonged state of hibernation and when released, they are disoriented and fly long distances before acclimating and starting to feed in earnest.

As floral noted, virtually all the suggestions or recommendations for companion planting are completely anecdotal and not substantiated by any scientific evidence. Because some combos seem to work in your garden does not mean there is a correlation or the results can be duplicated elsewhere.

Inexperienced or uninformed gardeners will believe everything they read, unfortunately.

I don't want to come across as negative but I also don't want the OP to waste time and money following unproven anecdotal suggestions. Practical help with scientifically supported strategies is what they need and companion planting isn't such a strategy.

No you are not negative, just very knowledgable. We are amateur gardeners that just want something pretty and fun. Most gardens are very productive in spite of us lol.

There can be a nugget of truth in some of these old gardener's anecdotes that we pass along.

I would not follow some random Influencer on YouTube. Read a book.

In a greenhouse ladybugs do work and are used commercially.

In my garden the ladybugs come of their own accord if there is food for them.

The nice photo with the flowers in the garden reminds me that peas and beans are legumes that fix nitrogen into the soil and act as natural fertilizer for the other plants. Those are the best companion plants. Clover does too and provides food for bees.

If you want ladybugs, quit spraying bug spray. Those red and black ”worms” are lady bug larvae and eat more than the bugs themselves!

I don't think you are being negative either. Companion planting has a lot of folklore in it. It's wise to be wary and check the tales with more current science to see if there is anything to it or not. Sometimes the folklore lingers, like basil making tomatoes taste better. Maybe way back folks just really appreaciated fresh basil and a tomato eaten right there in the garden. I know I've seen folks say how good eating right out of the garden is. I've appreciated the tasty snack myself. Perhaps the sweetness is just the appreciaton of the eating moment. Or at least, that's the only meaning I take from it in our modern age. I don't know of any studies to imply otherwise.

As a comparison, dill used to be more under the companion planting title. As we have learned about it as a host plant for the brachnoid wasp, it's been moved more over into the intergrated pest management title. I've not seen any study to suggest dill makes tomatoes taste better, like basil. But I have seen study and observed in my own garden the brachnoid wasps and the ricing on hornworms... that I don't really get anymore. Knock on wood, lol.

Some people have some success with trap planting. There have been trap planting studies. But much like other companion planting, often it's overly folklored and treated like a magic bullet. If you plant a trap squash and just leave it, it turns from a trap into a breeding ground. If your nasturium is getting coated in critters, pull it and kill the mass. Or sometimes it's using that trap plant to find you got a critter problem and hold off on planting that attractive plant till you got your garden under better control.

I also include weeds in my planting companions. Some of them tell me what is needed or abundant in a bed. Others might provide an eating crop of groundcover between plantings. Some of them provide feed for the gardens in different ways.

On a bigger yard scale, trees that have alleopatic chemicals are bad companions for a lot of other plants. Black walnut is noteable for jugone. Back down to the garden size, garlic has an alleochemical too, diallyl disulfide, so it can be a poor companion to some other plants. It has a negative impact on nitrogen fixing, and on to legumes. Some plants aren't bothered or even have a resistance to that particular chemical. Or can be helped, like it can induce a resistance to some diseases in some cucumbers.

OK, lets address the legumes fixing nitrogen question. Yes, they have root nodules which do this. But the nitrogen is not available until the plants are dug in, cut down or die back. Then the roots decompose and the nitrogen is released. So, just having living beans planted next to a crop doesn't help. Therefore, I never pull beans up at the end of the season. I cut them down.

I leave beans in the ground for the same reason floral. Where garlic comes in as a poorer companion for them is the diallyl disulfide can have a negative impact on the way the nodules form/process, and then on to the ability for those nodes to fix nitrogen.

So for instance in a landscaping way. If I had a slope. I might plant beans upslope of the garlic, and cucumbers downslope of it if I could. Or if I was dealing with raised beds, I might put the beans in a different bed than garlic. Not because the garlic will make my beans "unhappy", but because I can get better benefit out of my beans nitrogen fixing ability if I keep them in separate raised beds.

I've never heard of the plant trap method...but why attract pests in the first place?

Trap plants aren't supposed to attract in the first place. They are meant to be used if you already have an issue with a pest.

With something like squash bugs. The adults overwinter in the garden litter or mulch from the previous year. When it's warm enough, they emerge, looking for a squash plant to mate and lay eggs on. So you plant out a tender squash plant or two as early as they want to emerge. They find the trap squash, mate, start to lay eggs. And before the eggs hatch, you pull the plants and destroy them. It can help disrupt the life cycle.

But using a trap plant is like using a mousetrap. You only set it if you have the pest, and get rid of the trap as soon as the pest is caught in it. If you wait too long to pull the plant, it becomes a breeding ground instead.

I've used trap plants in the past, particularly to disrupt a squash bug issue and a bean beetle issue. But I've not desired to do so in a while. I feel it takes some dedication and minding to the traps. And I just use other methods more often now.

Our bugs don't overwinter, they feed all year long in California.