Fair warning, this is going to be a longer post. But partly that’s because there are so many pictures. I will start with the overview, then go a bit deeper into the weeds (literally and figuratively). To help you navigate more quickly, here’s a sort of table of contents that will quickly take you to the information you may be most interested to read:
Remember back in June when I told you about the different techniques we were comparing for establishing habitat for beneficial insects? Time for an update! Here’s a brief, two-page summary of the first year of this project. For all the juicy details (and lots of pictures), keep reading!
First, remember that when I say “beneficial insects”, I mean both pollinators and natural enemies of pests. (Technically, arthropod would be a better term than insect, because spiders and predatory mites are some of the beneficial creatures we’d like to attract.) Fortunately, the same type of plants provide food and shelter for both pollinators and natural enemies on your farm or in your garden.
We used six different techniques to establish this habitat during Spring, Summer, and Fall of 2018. Treatment E was our control, where we did nothing but mow (after initial herbicide applications).
|Treatment||Fall 2017||Spring 2018||Summer 2018||Fall 2018|
|A||Herbicide||Herbicide, transplant||Weed 2x||Replace dead plants|
|B||Herbicide||Till, transplant, mulch||Weed 2x||Replace dead plants|
|C||Herbicide||Till, direct seed||Mow 3x||Mow 1x|
|D||Herbicide||Till, plant buckwheat||Mow 1x, till, plant buckwheat||Mow 1x, transplant|
|E – control||Herbicide||Herbicide||Mow 3x||Mow 1x|
|F||Herbicide||Till, lay plastic||Continue solarization||Remove plastic, direct seed|
|G||Herbicide||Herbicide/till||Herbicide 2x, till 1x||Till 1x, direct seed|
We transplanted the following species in treatments A, B, and D:
|Common name||Scientific name||Number of plants in each 5 x 23 ft plot|
|Anise hyssop||Agastache foeniculum||2|
|Common milkweed||Asclepias syriaca||3|
|Blue false indigo||Baptisia australis||2|
|Lanced-leaved coreopsis||Coreopsis lanceolata||3|
|Purple coneflower||Echinacea purpurea||2|
|Wild bergamot||Monarda fistulosa||2|
|Tall white beard tongue||Penstemon digitalis||3|
|Black-eyed Susan||Rudbeckia fulgida va. Fulgida||1|
|Little bluestem (grass)||Schizachyrium scoparium||11|
|Showy goldenrod||Solidago speciosa||1|
|New England aster||Symphyotrichum novae- angliae||3|
|Ohio spiderwort||Tradescantia ohiensis||2|
|NY ironweed||Vernonia noveboracensis||2|
|Golden alexanders||Zizia aurea||3|
We planted seeds in treatments C, F, and G. The seed mixture we used was the Showy Northeast Native Wildflower & Grass Mix from Ernst Seeds, which included a more diverse species mix. This mix changes a bit from year to year. If you’re interested, you can learn about the details of the specific mix we used here.
Labor and costs
Not surprisingly, there were big differences in how much time and money we spent on different treatments this first year. The costs and hours below are for a total area of 460 ft2 (0.01 A) per treatment. Most of the cost differences are due to the huge difference in seed versus transplant expenses. We paid about $2 per plant and needed 180 plants for each treatment. In contrast, we spent about $12.50 on seed for each treatment.
|Treatment||Supply costs||Time (person hrs)|
|A – spring transplant||$417.12||10.92|
|B – spring transplant & mulch||$539.29||20.4|
|C – spring seed||$17.75||4.30|
|D – buckwheat & fall seed||$390.55||10.3|
|E – control||$2.32||2.6|
|F – solarize & fall seed||$148.02||10.2|
|G – herbicide/tillage & fall seed||$22.04||6.2|
But, there were also big differences in how quickly the plants established. By September, both treatments (A and B) that had been transplanted in the spring looked like well-established gardens, with large, blooming wildflowers.
We were generally pleased by how well most of the spring transplants survived. Although all the transplants came in 50-cell flats, some were larger than others, and the larger transplants survived better. We were fortunate to be able to plant into nice moist ground, so except for a little water on the day of transplanting, we didn’t irrigate. Survival might not have been as good if we’d had different planting conditions.
In contrast, the much less expensive treatment C was not looking too impressive even by October. A few partridge peas and blackeyed Susans bloomed this year, but otherwise it didn’t look much different from the control plots. In mid-summer, it looked like we were growing more ragweed than wildflowers.
Two of the treatments (F and G) were planted with seeds this fall, and one treatment (D) was transplanted this fall. So it’s really too early to tell how successful those treatments were. Stay tuned for more updates!
What about weeds? The graph below shows the average percent of the surface area of each plot that was covered with weeds versus planted beneficial habitat species on September 19, 2018. (Thank you, Bryan Brown, NYS IPM Integrated Weed Management Specialist for doing a weed assessment for us!) While we spent about the same amount of time weeding treatments A and B (the time difference is due to the time spent mulching treatment B), we achieved much better weed control with the mulch than without it!
In treatment B, we spread chipped shrub willow mulch about 3 inches deep around the transplants. If I were to do this again, I would spread it thicker. I was disappointed with how many weeds were growing through the mulch just a month after transplanting.
But weeding twice during the season pretty much took care of the weeds in treatment B. Treatment A was also weeded twice, but as you saw in the graph earlier, weed control by the end of the season was not as effective.
I think we’ll have to wait until next year to really understand how weed control is working in treatment C. Remember, the strategy was to slowly deplete the annual weed seedbank by allowing weeds to germinate, but preventing them from producing more seed. This is not supposed to be a quick establishment method, and it wasn’t.
Buckwheat as a weed-smothering cover crop
By the time Bryan did our weed assessment, it had been 3 weeks since we mowed the second planting of buckwheat. Ideally, we would have transplanted shortly after mowing the buckwheat. But, the second crop of buckwheat was starting to set seed by the end of August, and our transplants weren’t scheduled to arrive until the end of September. So we mowed the buckwheat early to prevent it from contributing its own seed to the weed seedbank. But this meant that a lot of weeds had time to germinate before we transplanted the habitat plants. The buckwheat certainly suppressed a lot of weeds during the growing season, and I hope that this will help reduce weeds next year.
Overall, we were pleased with how the solarization worked. We laid down 6 mil clear plastic (leftover from a nearby high tunnel) in early June, and did a little weed control around the edges of the plastic just once during the summer to prevent more weed seed production and to prevent shading of the plots.
We also learned that solarization will not control purselane. In contrast, the purselane thrived only under our clear plastic, and nowhere else in the field. The plot that had the most purselane also had the most other (mostly grass) weeds. I think the purselane pushed the plastic away from the soil and reduced the temperature a bit, allowing other weeds to grow.
Some other plots were virtually weed-free when we pulled the plastic up in October. (Did you see how large the error bar was for weeds in treatment F in the weed graph above? This means there was a lot of variability between plots in this treatment.) Our soil temperature probe happened to be in the plot with the most purselane, and we still achieved maximum soil temperatures of 120 °F (at a depth of about 3 inches), compared to 90 °F in a nearby control (treatment E) plot.
Repeated herbicide and tillage
At the weed assessment in September, the plot that had been alternately treated with herbicide and tilled looked best in terms of weed control. Like treatment C and all the treatments planted (by seed or by transplant) in the fall, I think we’ll get a better idea next year of how effective this method was at suppressing weeds.
One thing we struggled with this fall was deciding when to plant the wildflower and grass seed mixture. One source recommended the seeds be planted sometime between October and December. We were cautioned that if we planted the seed too early, some species (especially blackeyed Susans) might germinate this fall, and the young seedlings would be killed by an early frost before they established. But we were also afraid of waiting too long and not being able to till the soil (treatment G, only) if it got too wet. And we wanted a nice smooth seedbed. In treatment F, we suspected that leaving the clear plastic on into November would protect the weeds from the cooler weather. But we worried that taking it off too early would only allow more weed seeds to blow onto the bare ground.
Finally, we compromised and planted the seeds on October 18 and 19, after our first hard frost, and once it looked like the nighttime temperatures would be in the 40’s (or below) for the next 10 days. It was only a week after the last tillage in treatment G, and the soil was still relatively dry. Those who live in the Finger Lakes know that late October and early November were pretty wet this year, so I’m glad we planted when we did. If you are trying to time fall seeding, I would recommend that you keep an eye on the 10 day forecast to see when temperatures are starting to cool. But if you get a dry sunny day to plant and it’s reasonably cool, I wouldn’t delay.
First, think about the time, money, and equipment you have available, as well as the area you’d like to plant. There probably isn’t a single right way to establish this habitat, but there may be a best way for you.
You can find more details on the techniques we used (and some links to other resources) here.
This post was written by Amara Dunn, Brian Eshenaur, and Betsy Lamb.
This work is supported by the Crop Protection and Pest Management Extension Implementation Program [grant no. 2017-70006-27142/project accession no. 1014000] from the USDA National Institute of Food and Agriculture.