Once we started farming in earnest, we started looking at the "old-time" marigolds, with the understanding that they tended to exhibit some of the properties were were looking for in annual companion flowering plants. They are pollinator friendly, they can be helpful in dealing with harmful nematodes, and they do have some pest-repelling properties.
Bring on the Blooms!
One of our favorites as a companion marigold is Red Marietta (Tagetes patula), an heirloom variety that has been offered by Seed Savers for as long as we can remember supporting them. You might notice that these are not the big, double blooms so many nurseries trot out there for us all to purchase in the Spring. Instead, you get a fairly simple flower and you get a plant with that nice "marigold smell" whenever you brush against them.
The other thing you get? Lots and lots of flowers. And with them? Lots and lots of pollinators!
What strikes me most about the pollinator activity in the Red Mariettas is that there is a diversity of insects. There are honeybees, of course. But, during this visit there were two or more types of bumble bees, some orchard bees, other bees I didn't get a really good look at, and even an interesting moth checking out the pollen on a flower. If you look, you can find a pollinator in the picture above.
We like to start some marigolds in trays to give them an early start, but that doesn't stop us from also direct seeding rows of them too. Marigolds really don't seem to mind a heavy seeding to help them discourage surrounding weeds. And, once they are established, they are low maintenance plants. For us at the farm, this is major selling point.
Many gardening sites recommend that you deadhead marigolds (remove spent flowers) to keep them blooming. But, we've found that Red Marietta doesn't really require that you do that. Once they start, they keep going deep into the season. They are even tough enough to survive light frosts and continue to brighten your day for a while longer than other annuals. Yes, they might be a bit singed - but if you can tolerate their less than perfect appearance, they will still reward you with color and they can feed the pollinators that are still actively seeding food.
At the Genuine Faux Farm, we can often have a nice hedge of Red Mariettas that can be as tall as two feet high and usually just as wide. You might find a Red Marietta here and there, sprinkled into rows of veggies. They might appear in tomato, pepper, brassica or cucurbit (vine crop) rows.
There are many types of nematodes out there in the world. Some of them are considered beneficial organisms and there are those who actually purchase them to try to control pests. Others, such as Root Knot Nematodes, can be a problem for producers of certain crops - like tomatoes - especially in southern states. There are numerous practices to deal with these harmful nematodes, but one that is often not discussed is the use of the traditional marigold.
The root systems of traditional marigolds produce something that Root Knot Nematodes do not like, so their presence can actually help to deter problems with these and other harmful nematodes. No one argues that traditional marigolds don't reduce the presence of detrimental nematodes. The reason it is not discussed as a commercial strategy for control? It's a matter of two things - the method and the effectiveness.
Simply having marigolds in an adjacent row is not necessarily going to provide sufficient protection for a row four to five feet away in a field, especially if it is already infested with Root Knot Nematodes. On the other hand, if you were to plant marigolds in row with the tomatoes, you might see some benefit, but it is not likely to completely turn around an infestation in one growing season. And, for many growing systems, adding diversity in the crop row is usually seen as a non-starter (I can talk about that one another day).
On the other hand, if a person were to seed out a field that has these nematodes into marigolds for a year and then worked them into the soil prior to the next crop, you just might see a difference. It is not unlike running a fallow field or solarizing a plot. But, in my opinion, the best solution would be to maintain diversity in the plantings and mixing marigolds into that planting BEFORE Root-Knot Nematodes become a problem in the first place.
In other words, do things to avoid making a perfect environment for the pest to really take hold without any challenges. Mixing in marigolds into the rotation and periodically in the cash crop rows can help maintain a balance. Will it work perfectly? Of course not. Nature is far more complex than that. But, if you can do things to keep the balance longer without having to fall back on a drastic solution - why wouldn't you?
Diversity in Many Levels
While I admit that I do like growing Red Marietta, it is not the only marigold we grow on the farm. Another one of our favorites from Seed Savers is Starfire Signet (Tagetes tenuifolia).
Signet marigolds are among the four species that humans tend to cultivate. These plants have smaller, simpler flowers and the Starfire Signet has lacy, fine leaves, which creates an attractive mound even before the flowers appear.
We have noticed, over the years, that pollinators of different types have preferences for flower types and sizes. The biggest bumble bees will land frequently on the larger zinnia while smaller beneficial insects might prefer the diminutive flowers on a Starfire Signet plant. As I walked from one cluster of marigolds to another I noticed the composition of my pollinator friends changing to match the plants.
I recognize the very human desire to keep things looking attractive in accordance to what we like to see. I also understand what it means to keep things ordered so farmers, like ourselves, can efficiently get work done and produce food. But, I reject the idea that we cannot support diversity and attract pollinators without wholly giving up on the human aesthetic or the desire to keep work manageable.
Marigolds are one of the keys for food production systems, in my opinion. Don't ignore them, embrace them to help make your world merry and bright.