Frequently Asked Questions

In the news

Expand all

Mystery seeds in the mail? Do not plant them. Expand for more info.

In late July 2020, a news story hit about "mystery seeds" arriving by mail. Do not plant these seeds. Visit this page for information from the Minnesota Department of Agriculture.

Additionally, the Midwest Invasive Plant Network (MIPN) issued a special bulletin explaining DOs, DON'Ts, and what we know about this matter.

MIPN Special Bulletin: Mystery Seeds in the Mail (July 29, 2020)

My site is set up. Now what?

Expand all

What does the year look like at a glance, in terms of activities?

The at-a-glance calendar below provides an overview. For details on the activities, refer to these how-to documents:

2020 Timeline

Should I water my site? (No - expand to read more)

Please do not water your site. Because weather is part of what we are testing in this experiment, it is best to leave your site undisturbed.

Should I weed my site?

When it comes to removing plants from your site, there are only two expected activities:

  1. Remove buckthorn before set-up (i.e., spring 2020).
  2. Cut "non-seeded" buckthorn. Every 4 to 6 weeks between June and August every summer (2020-2022), carry out the steps on this how-to document.

No weeding is required beyond these two core activities. If you want to weed out invasive or nuisance plants, you have choices. If you do additional tending, we have two requests of you:

  1. When you choose a plant to remove (e.g., garlic mustard, burdock, etc.), carry out the removal uniformly across all 6 squares.
  2. Record your activities using your summer datasheet, taking note of which plant(s) you removed, when you did the "weeding," and what methods you used (e.g., cutting). If you need to reprint your summer datasheet, it is page 3 of this PDF.

How can I tell apart buckthorn and cherry plants?

For seedlings and young plants, pay attention to leaf shape and vein patterns. Examine this image (via which shows buckthorn leaves in the upper left and a cherry leaf in the lower right. The bullets below walk through what to look for:

  • Cherry leaf margins (edges) have small sharp teeth
  • Buckthorn leaf margins have small rounded teeth
  • Cherry leaf veins form fairly straight lines from the midrib to the margins
  • Buckthorn leaf veins are distinctly curved, forming arcs that originate along the midrib and point toward the leaf tip

For older plants, inspect additional traits such as bark and fruits.

These resources give detailed descriptions of common buckthorn's distinctive traits:

I don't see native plants growing. Is this normal?

Yes, this is normal. Don't be discouraged if you don't see much new growth this year. Unlike the garden-like results of cultivated seeds, vegetation from native seeds will start out spindly and is typically slow to establish. These signs do not mean the experiment isn't working.

Keep in mind, the Cover It Up experiment tests how well native plants shade out buckthorn seedlings, not older plants. When buckthorn emerges from seed, it is quite sensitive to light competition, so even modest establishment of native plants may effectively suppress its growth and survival.

The amount of light at your site will strongly influence what you see in terms of native plant growth from the seed mix. In sunnier sites, plants will emerge in greater density and at a faster pace compared to shady sites. Intermediate shade levels will have intermediate establishment rates. Other factors like soil moisture and nutrients also play a role.

Here are some guidelines on what you might see and how long it takes:

  • In sunnier sites:
    • 2020: spindly grasses
    • 2021: wildflowers show up but are sparse
    • 2022: vegetation thickens up and flowering is more dense
  • In shadiest sites:
    • 2022: spindly grasses might be all that appear

Below are images of experimental sites where native seeds were spread in February of 2017.

Murphy Hanrehan Regional Park Fall 2018 - very open canopy

Above: Very open canopy (much light reaching understory) at Murphy Hanrehan Regional Park. Located in an oak wilt gap within an oak canopy. By end of year 2 (fall 2018) modest grass and herb cover.

Murphy Hanrehan Regional Park Summer 2019 - very open canopy

Above: Very open canopy (much light reaching understory) at Murphy Hanrehan Regional Park. Located in an oak wilt gap within an oak canopy. By year 3 (summer 2019) there is diverse grass and herb cover.

St Croix Watershed Research Station - fall 2018 - mild shade

Above: Mild shade at St Croix Watershed Research Station. By end of year 2 (fall 2018), still only a sparse cover of grass.

Murphy Hanrehan Regional Park Fall 2018 - very shady

Above: Very shady (basswood-oak canopy) at Murphy Hanrehan Regional Park. By end of year 2 (fall 2018), seeded grasses (wild ryes) are still very sparse. This example is a case in which shade has limited establishment of native seeds.

What observations and data are expected in May 2020?

Expand all

What makes a useful site map?

Your site map is an important tool for the three-year course of this study. It diagrams the configuration and features of your unique site. One important function of the site map is to show you where to stand when taking photographs of your squares. We will be taking "time series" photos of each square. In order to compare these photos, we'd like to use the same vantage point again and again. Below is an example site map with a list of all the details that make it a useful tool:

Site map example
Example of a site map
  • Site name
  • Your name
  • Site perimeter
  • Anchor point ("AP")
  • 6 clearly numbered squares
  • An "X" in one corner of every square, showing where to find the metal tab
  • Along one edge of every square, the word "PHOTO" indicates where to stand so the metal tag is on your left
  • Sketched natural features such as logs, tree trunks, etc.

What are we looking for in the photographs of my squares?

In May 2020, the photographs of your squares capture your site's "baseline" condition. What did your site look like before the experiment started. Most importantly, we will be taking "time series" photos of each square. That way, you can examine how your site changes over time. You will be able to see the most interesting results if you use the same vantage point again and again. This is why it's helpful if you stand in the middle of one edge, with the metal tag to your left. Below is an example photograph and a list of what makes this photograph useful:

Example - photo of square
Example - photograph of Square 6
  • Photo marker indicates which square this is
  • Metal tag is in the lower left
  • Vantage point is a birds-eye view, standing at the center of one edge
  • All 4 corners are in the field of view
  • The square is framed snug within the field of view, without too much background or surrounding area

Questions about

Expand all

What is geoprivacy and how does it work?

Anecdata's geoprivacy feature is enabled for the Cover It Up project. Geoprivacy obscures the publicly-displayed latitudes and longitudes of observations by up to 1/5th of a degree. When you add an observation, it has a pinpoint on a map (pictured below, left). When your observation is viewed by others, the location appears as a box around a general area (pictured below, right).

Anecdata - "Use this location" pinpoint on map
Anecdata - Observation veiw, general area

When I upload photos, what file type should I use?

Anecdata accepts a variety of file extensions including JPG, PNG, and BMP. However, it does not accept TIF or PDF files. If you encounter issues uploading photos, please contact

I noticed something interesting at my site. Should I report my observation?

Yes, we'd love to hear about what you noticed. When you are at the Anecdata project page, click "Add observation." Choose the datasheet called "Non-standard observation." This is a datasheet for reporting data other than what is asked for in our standard protocols. If you took a photograph, please upload it. Also, please write a comment describing what you saw and why it is important.

Questions about native plants and restoring forests and woodlands

Expand all

Where can I buy native plants?

This page compiles a list of nurseries and other vendors that sell native seed in the Midwest:

What do we know about restoring forest or woodland vegetation after removing buckthorn?

In general, we know more about restoring grasslands and prairies than we know about restoring forests and woodlands.

We know from our experiments that densely planting shrubs (primarily red and common elderberry) or a mix of balsam fir and sugar maple can severely reduce buckthorn survival and growth. In areas where the canopy is more sparse, preliminary evidence suggests that a herbaceous seed mix (largely comprised of Elymus wild ryes) can suppress buckthorn. However, more supporting evidence is needed for this second approach and this is the goal of Cover It Up Citizen Science . By conducting experiments with herbaceous seed mixes across the state, we can not only find out if it is effective, but also where it is effective based on local conditions.

In general, these approaches suppress new growth (i.e., seedlings) rather than re-sprouting buckthorn plants. Additionally, a high density is necessary for these seeding or re-planting approaches to succeed. Finally, every site is unique and these replacement species may not thrive in all settings.

Questions about setting up my site

Expand all

I haven't received my supplies. When should I expect them?

Supplies are being shipped in batches in April and May 2020. Please contact Abbie at to ask about your shipping date and tracking number.

Should I remove leaf litter before applying the mix of native seeds?

No, for this experiment please distribute the native seeds directly onto the forest or woodland floor.

Why didn't my kit contain buckthorn test seeds?

The planting of buckthorn test seeds has been postponed. Please carry out the other steps of your set-up (mark squares with flags, draw a site map, take photos, and distribute native seed mixtures). Buckthorn test seeds and the round planting discs will be shipped to you in approximately early May.

What native plant species are in the seed mixes?

The project seed mix includes 29 native Minnesota plant species. These species were chosen because they:

  • may provide dense shade in situations ranging from fairly open woodlands through to closed forests
  • have approximately state-wide ranges
  • and are available locally through Minnesota seed suppliers.

Here is a link to the species list:

My site has invasive plants other than buckthorn. Should I remove those, too?

If you can confidently identify the invasive plants and are able to remove them, then we encourage you to do so. Examples of plants for this question include garlic mustard and Tartarian honeysuckle. Whether you decide to leave or remove invasive plants, please carry out your decision uniformly across the entire site (all six squares). Also, if you decide to remove invasive plants, please write down the following information:

  • Which species you choose to remove
  • What technique or tools you used
  • Approximate time spent doing the removal

It's a good idea to keep this written note with your Cover It Up materials. We will collect this information later in the season. These guidelines also apply to non-invasive plants you may prefer to remove from your site (e.g., a native plant such as prickly ash).

There are many deer in my area. Should I protect my site with fencing?

The choice to fence off your site or not is left to you as the participant. Either choice is okay, so long as all six squares are treated uniformly.

Can I get a sign that explains Cover It Up research to curious passers by?

Yes. Some Cover It Up experimental sites are visible from public trails. Putting up signage accomplishes two things: First, we request that people stay on trails and not disturb the site. Second, we can give people information about Cover It Up research and our shared goal to restore native plants in Minnesota forests. Below is a link to a PDF you may print, protect by lamination or a plastic sleeve, and then display at your site.

Questions about study design

Expand all

Why do we plant buckthorn test seeds?

We understand that it seems counter-intuitive to plant buckthorn for a project aimed at removing buckthorn. However, to understand this plant, we're working closely with it—and yes, even planting it in a short-term, removable way—so that in the long term, we learn how to reduce it. In order to identify conditions that result in buckthorn failure, we need known numbers of buckthorn plants at known locations in every square, all starting off from seed at the same time. And although it may seem that buckthorn is ubiquitous, in truth, its occurrence (i.e., where it appears in the environment) is extremely variable. That is why this experiment uses a small number of "guinea pig" buckthorn, all of which will be (easily) removed at the end of the study before they produce any seeds.

People plant native species all the time. Hasn't this been done before?

There is considerable evidence that removing invasive plants and replacing them with native species reduces re-invasion of grasslands. However, there's actually little evidence on whether this is effective in woodlands or with woody invaders (Schuster et al 2018, link to PDF below). There haven't been any published tests of this idea with buckthorn. So this is a question we still need to answer.

How else have you tried to find out if we can use native plants to control buckthorn?

We first tried to answer this question in 2016 using a retrospective approach (i.e., making observations of conditions as they are without running an experiment). We surveyed about 40 sites around Minneapolis/St Paul where buckthorn had been removed within the past few years. These sites had either been seeded with native plants or not. We measured buckthorn and native plant abundance, soil properties, tree canopy, and several other variables to try to isolate the effect of seeding. We saw that on average, re-seeded sites had about half as much buckthorn re-invasion as unseeded sites. However, the results were not definitive because the data were highly variable, and because herbicides confounded the effect of seeding. The abundance of buckthorn and native plants vary from place to place depending on all kinds of factors such as history, soil, slope, deer abundance, tree canopy, and so on. This variability is so great that retrospective surveys have limited use for determining if native plants suppress buckthorn. The way around this is to conduct experiments that control some of the variability by a) having adjacent seeded and unseeded squares and b) having a consistent number of buckthorn seeds planted around flags to assess how seeding affects buckthorn growth.

Won't buckthorn pop up on their own in my experimental site?

Maybe, but we can't count on it. Two factors make it so we can't count on new buckthorn plants emerging from seeds that are already present in the soil (i.e., seedbank). The first factor is the age of seeds and the second factor is their patchy distribution. As for seed age, most buckthorn seeds germinate within 1 year and a small portion will germinate after 2 years. (This is based on several large experiments that we have conducted over the past 3 years.) Therefore, at sites where buckthorn was removed more than one year prior to this experiment, the existing seedbank is only marginally viable.

Second, the seedbank is quite patchy because buckthorn fruit production varies from plant to plant. For example, a well-lit fruiting (female) buckthorn may grow next to a non-fruiting (male) buckthorn (or even a female plant that is too shaded to produce much fruit). After those plants are removed, one may see a dense carpet of buckthorn seedlings next to an area with few or no seedlings. Because of buckthorn's patchy seedbank, the seedbank in the squares at your site cannot provide a reliable "apples-to-apples" comparison between where you apply native seeds and where you do not.

The factors above are consistent with what we observed in an earlier phase of Cover It Up research: In 116 plots at 7 sites around the Twin Cities where buckthorn was recently removed, we monitored buckthorn seedlings in re-seeded and non-seeded areas. Buckthorn emerging from the natural seedbank were too variable to detect any effect of seeding, whereas buckthorn test seeds that we planted around flags showed reduced survival and growth with re-seeding at some sites. By having citizen scientists repeat the latter protocol across the state, we can find out more about site conditions that are conducive (or not) for using native plants to control buckthorn. Because naturally occurring seedbanks vary in age and patchiness, it is necessary to plant a known number of buckthorn test seeds at known locations.

Will the buckthorn planted as part of Cover It Up take over my property?

No. We've run similar experiments in approximately 800 research plots around the Twin Cities. Across all those plots, we've never seen a test buckthorn grow more than 2 feet tall  (most are shorter than 1 foot), or large enough to fruit, within 3 years (the duration of Cover It Up Citizen Science). Most importantly, participants are required to remove all buckthorn arising from seed at the end of the experiment. Given how small buckthorn are at that age, they are easy to uproot and will not resprout. So, if experimental areas are managed according to the project's protocol and the agreement that we enter into with participants, there is very little risk.