Gardener's Question Time

[David B]

Just because I have a couple of questions for the gardeners.

I remember in one place I worked, marigolds were planted along with tomatoes. The rationale for this was that the marigolds were useful for pest control on the tomatoes, though I forget quite how.

So my questions -

Are there plants which you grow in conjunction with others, with the aim of assisting pest control and/or soil fertility?

If so, what plants do you grow to complement each other, or to help one of them?

And does planting different plants in conjunction with each other for pest control/fertility/whatever actually work?

I'm interested in answers to these questions, but feel free to pose more questions in this thread.

David

[Monad]

Not Marigolds as such (Calendula) but African marigolds (Tagetes). This is because they give off a pungent smell that is reputedly a deterrent to greenfly and other pests (supposedly even nematodes in the soil) but at the same time they attract insect predators like hoverflies. There are a number of other species in the Asteraceae that contain pyrethroids and other compounds that are natural insecticides so there maybe some truth in it but I don't know of any scientific studies of this.

On the other hand it is well established that rotation of crops/plantings and avoidance of monocultural practices (or at least replenishment of soil for plants like Roses) keeps down the number of soil pests and diseases while plants like Legumes (that have root nodules that fix nitrogen in the soil) aid the fertility of the soil. Other plants like Potatoes help break up the soil structure. Plants like Comfrey can also be dug back into the soil as natural manure and also facilitate the soil structure as they also make good worm food.

Some plants are also planted as decoys to attract pests away from the main crop/flowers - Nasturtiums for example are a magnet for Cabbage white caterpillars. Also growing some so called weeds like nettles help to maintain the biodiversity of the garden which increases the number of predators around.

[Cath B]

I'm currently growing marigolds and nasturtiums partly as companion plants but also because they're edible and pretty.

I'm growing my onions and carrots together as they are said to mutually discourage each other's pests (including the dreaded carrot fly).

I don't know how much truth there is in any of this.

The crop rotation I'm more-or-less following is:-

Plot One Potatoes
Plot Two Beans, peas, spinach and chard
Plot Three Brassicas
Plot Four Carrot and Onion Family

Next year plot one becomes plot two etc.

Manure from the chickens is going where the beans will be planted.

[Christina]

David, if you google for 'companion planting' you'll find all sorts of information.

[reddhedd]

Monad, I now understand why my marigolds did nothing but look pretty; thank you for that!

I do plant flowers around, but because they are pretty and edible, as Cath B. does.
I want to eventually have my whole yard planted with useful or edible herbs, veggies, flowers, trees, etc.

I have more luck focussing on what not to plant near something else.
For instance, most things won't grow near sunflowers; they give off some sort of compound that inhibits other plants.

I also have success with hand picking and introducing natural predators; each season I buy a box of ladybugs and a praying mantis "egg". The ladybugs eat the aphids and soft bodied pests, and by the time the praying mantis babies have hatched out and are big enough to be a threat to them, the ladybugs are done eating and have flown away. Plus they are so cute!

Between that and the spray I make out of water, garlic, Ivory soap and tobacco, I have plenty of produce to eat and share.

[Christina]

We generally have enough ladybugs to keep the aphids under control but I did buy them one year. It never occurred to me that I shouldn't release them in the high heat of the day, but they immediately took off for some shade and I never saw more than a few of them together. I've used water, garlic and cayenne to make sprays but not tobacco. I'll have to try that.

[Cath B]

most things won't grow near sunflowers; they give off some sort of compound that inhibits other plants.


I didn't know that specifically, but did know that plants are big, big, big on chemical warfare.

[Monad]

Yeah that's quite common - like Black walnuts do the same

[Christina]

That's good to know. I've always put sunflowers off in a sunny place by themselves because I like how that looks but I didn't know that it would be a problem if I had put them near other plants. I have a lot of seeds starting to sprout now and I'll be sure to keep them far from anything except weeds. It's probably too much to expect that they would kill those off for me.

[reddhedd]

It's probably too much to expect that they would kill those off for me.

Yeah probably! :D

This is one of my sig lines; i find it to be quite accurate:

When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant. ~ Unknown

redd

[Christina]

When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant. ~ Unknown

I love that. :) I've learned that the only way to get rid of some weeds is to do it in the pouring rain or soak the ground and dig through the mud to find the roots, unless it's mint and then you might as well give up or move out.

[sohy]

I don't have any questions but I do have the answer. :D If I learned only one thing when I took the master gardener course it was this. Amend your soil. Test your soil and amend it until it's just right. If your stuff won't grow, it's probably because you didn't properly amend your soil. Yup. Be sure and amend your soil before you plant. Is that clear now? Did y'all amend your soil? That's why I gave up gardening in Georgia's red clay. Now if I grow anything, it's in containers filled with potting soil. It's hard work to amend that shit we call soil in Georgia.

[Christina]

I don't have any questions but I do have the answer. :D If I learned only one thing when I took the master gardener course it was this. Amend your soil. Test your soil and amend it until it's just right. If your stuff won't grow, it's probably because you didn't properly amend your soil. Yup. Be sure and amend your soil before you plant. Is that clear now? Did y'all amend your soil? That's why I gave up gardening in Georgia's red clay. Now if I grow anything, it's in containers filled with potting soil. It's hard work to amend that shit we call dirt in Georgia.

Is everyone taking her advice? Amend your soil before you plant or you'll be digging things up later and doing it when you finally accept that they've been sulking for years. Trying to make it up with fertilizer later isn't going to cut it if it drains right through or runs off your soil.

[David B]

I don't have any questions but I do have the answer. :D If I learned only one thing when I took the master gardener course it was this. Amend your soil. Test your soil and amend it until it's just right. If your stuff won't grow, it's probably because you didn't properly amend your soil. Yup. Be sure and amend your soil before you plant. Is that clear now? Did y'all amend your soil? That's why I gave up gardening in Georgia's red clay. Now if I grow anything, it's in containers filled with potting soil. It's hard work to amend that shit we call dirt in Georgia.

What does amending soil consist of?

I'd make a guess, and say that composting must have a major role.

And, in the case of clay, I'd guess that giving it a bit of welly with a fork, and mixing some sand and perhaps gravel in, as well as compost, might be good?

David

[nygreenguy]

And, in the case of clay, I'd guess that giving it a bit of welly with a fork, and mixing some sand and perhaps gravel in, as well as compost, might be good?

David

It all depends on the plant. Some like it wet, some like it well drained, some like t well drained but moist!

[reddhedd]

I'm also suffering from the sucky stuff called soil in Georgia. I only grow veggies and fruits in raised beds.... I 'create' the soil from vermiculite, compost and peat moss.

For my non edibles, I dig down a foot and a 1/2 (making walls with the many rocks we find !) and drop in a load of compost...then wait a year before turning the soil and planting anything. Otherwise, nothing but ivy and kudzu grows...and very often, that's all that thrives anyway. :(

[sohy]

Amending the soil usually includes tiling in whatever your soil is lacking. Tilling is important, whether you do it by hand or with a tiller. Hand tilling is not for wimps like me. Compost is usually important too. Ideally, you should take a soil sample and have it professionally tested. In the US, we can go to our county extension office for this. The experts will tell you what you need to add. If your soil is too alkaline, they will tell you what type of additions you need to get the appropriate ph. Things like sand and compost improve drainage if you have our thick Georgia red clay soil.

It's possible that your soil may be just right without amending it, but that's unusual. If you limit your gardening to native plants, you can get away with much less soil preparation. Most gardeners want to grow more than just natives.

If you're lazy like me, you can let the birds you feed help you out. I have some beautiful camellias that birds have planted for me. I doubt they are native plants but they love the conditions where I live, so they thrive without any work on my part.

I won't try to plant anything outside of my pool area because of the deer. The deer love to eat many kinds of plants and there are lots of deer in my neighborhood. I don't mind them stealing from my fig trees, along with the birds and raccoons, but I'm not going to plant flowers and vegetables for them. Anyone else have a deer problem?

[Christina]

We would have a huge one if we didn't have that almost invisible black mesh deer fencing in the woods surrounding the developed part of the property. Not only would they munch through my whole garden, but the coyotes would follow them and then my pets are in danger. IMO things like cougar piss and other repellents don't work worth a damn.