Earth Sangha Native Plant Compendium

The Earth Sangha Native Plant Compendium is our attempt to list the species we predict to have in propagation at our Wild Plant Nursery sometime over the course of a year, though availability may vary based on demand or simply bad luck with seed. We intend for this to be an annual exercise and every year we will update the plant list and may focus on different educational material.

           

For our inaugural Almanac we have decided to focus on plant selection and choosing plants in ways that mirror natural and successional plant communities. Gardeners should see this as an extension of “right plant, right place” thinking – that the sort of assemblages of plant species that arise together in nature likely yield the greatest ecological value and that, with some care, we can choose to replant and restore areas in ways that approximate these plant communities.

           

This is not to say that there is no room for design or aesthetics! Especially in highly visible areas, we believe that an attractive space will garner support (maybe your neighbors will want to use natives too) and stick around longer (maybe the next owner of your home keeps the garden intact) and so adds to the ecological value of the landscape through spreading good will and hopefully mimicry. While we cannot offer design help ourselves, a thriving community of native-focused designers exists in Northern Virginia and we are happy to make recommendations.   

Our guidance will begin in the broadest possible way as we look at some easy-to-grow, high-value generalist species. From there we will look at four examples of natural plant communities that represent a range of natural forests in our region, and finally we will wrap up with a full plant list that also includes our own notes on habitat and growing conditions.

The advice in this Almanac is based primarily from our 20+ years as Northern Virginia’s largest grower of local-ecotype native plants. Over the years we’ve distributed hundreds of thousands of native plants across 300+ species – most of these plants going back to restoration projects. We do not just grow the plants, but we also observe closely their habitats and communities as we collect seed (sustainably, and with permission from landowners), and from years of working closely with ecologists across the region to protect and restore our native flora on both public and private lands.

           

That said, this is not meant to be exhaustive nor the only resource you may want to consult. In addition to our own experience, we have used data from Virginia Department of Conservation and Recreation’s Natural Heritage Natural Communities of Virginia data. You can find all the raw data online at (www.dcr.virginia.gov/natural-heritage/natural-communities/). Glenn Tobin, an Arlington Regional Master Naturalist, also has an excellent data-driven resource working from this data set (www.novanaturalcommunity.com). Descriptive habitat notes and the introduction on natural plant communities from the Flora of Virginia (edited by Bland Crowder) are also excellent resources. We have tried to add value here by spreading the word, including our own horticultural notes, and by focusing the data on species that are available to you through our Wild Plant Nursery

How to Choose Plants for your Garden

A lot of factors go in to determining what plants you want in your garden. In a traditional garden landscape, things like height, bloom period, color, texture, and other aesthetic concerns might make up the basis of those decisions. While those are still valid concerns to have – if we want to maximize the ecological value of our plantings, we need to begin thinking more along the lines of how ecologists approach a landscape and put these ecological concerns – that is, a consideration for how animal and plant life will interact and support one another in the garden – on equal footing with our own aesthetic enjoyment.

           

Before you even get started planting, you might want to consider two fundamental precepts that gardeners and ecologists alike refer to: “right plant, right place” and “first, do no harm.” At its most basic level, “right plant, right place” means putting a plant in a location where the conditions will allow it to thrive. Don’t put a plant of dry forest floors into a wet field and expect good results. While this is a simple idea, if you’re new to our native flora, it can be exhausting to figure out the right conditions for everything. We hope that our list of generalist species will help!           

 

The other basic concept, “first, do no harm,” tells us to consider the state a garden or restoration site is in already. It’s a reminder to identify plants before we remove them – maybe that ubiquitous groundcover you are removing is actually a native violet species that’s critical for early season moths that go on to feed birds in the spring – or to not alter the native soils or slope beyond what is absolutely necessary. Oftentimes, if we follow this advice, not only do we leave regenerating plant communities more intact, we also reduce the work we have to do to create a productive and attractive landscape.

         

Careful observation of our natural or successional areas is another valuable tool when planning our gardens, and is largely free. We’re lucky that even in a region as urbanized as the DC area, we have a great deal of parks, many of which are in reasonably good condition and can serve as reference sites for our own gardens. When you have a chance, visiting nearby parks and looking at what plants are growing there, when they bloom, how the change of the seasons drives changes to the flora, can be illuminating in understanding how our plants arrange themselves in nature. Observe, for example, that the vast majority of our forested, shady groundlayer herbaceous plant communities feature lots of open space of leaf litter. Not only is it uncommon (and usually because of invasive species) to find forests with dense uninterrupted forest floors that are green year-round, but the leaf litter is critical habitat for all manner of beneficial insects and amphibians. Notice too that almost all full-sun meadow environments are densely growing with many different species packed together even on sites with thin and dry soils. Compare these to most gardens and we find that the prevailing aesthetic is actually generally the opposite: dense shade plantings and sparse, mulch-heavy full-sun plantings.

           

That isn’t to say that we can’t put our thumbs on the scale and make some changes that deviate from the natural structures, but we should be aware  that the more we move away from natural arrangements of plants – whether that’s in terms of “right plant, right place,” or changing density of plantings, or introducing more exotic species – we run the risk of creating a landscape   that’s less accessible to the wildlife we want to protect and may be less conducive to healthy, robust plants and thus require more maintenance and upkeep.     

Good Habits for Good Habitats

We can all make a few cultural changes to how we treat our gardens and landscapes that helps them foster more wildlife. Think of these tips as ways to be good neighbors to the natural world:

  • Remove invasives. Some garden plants pose a direct threat to natural areas through their uncontrolled spread and inability to host wildlife. Globally these are a leading cause of biodiversity loss. If you have any in your garden, form a plan to replace them.

  • Mow less, mow higher. Lawns generally don’t support much in the way of wildlife so reducing lawns and replacing with native plants is a huge benefit. Where you must maintain a lawn, mowing higher (3”+) reduces harm to wildlife and limits drought stress on your grass.

  • Lights out. Limiting outdoor light at night reduces light pollution which kills thousands of moths that get confused and circle lights rather than pollinate and lay eggs.

  • Leaf it alone. Let your leaves naturally breakdown in your garden or compost them on site. Raking them off impervious surfaces like your driveway prevents excess nutrient runoff to streams, but if they’re on soil they will help create habitat and healthier soil.

  • Spray only water. Generally, if you choose the right plants, they won’t need a lot of extra watering. They also don’t need fertilizer, and spraying herbicides and insecticides in your garden will harm wildlife and native plants.

The easiest way to proceed then, especially for the beginner to native gardening, is to “think horses, not zebras” and go with common generalist native plants over rarer species. The advantages here are both horticultural and ecological. Many of these generalist species thrive on a wide range of habitats, making it easier to put the “right plant” in the “right place” and have good results. Most of these are also unfussy and robust and will establish quickly with little extra effort on the part of the gardener. Ecologically, common species tend to foster the most wildlife. While rare plants are definitely worthy of conservation, and may have specific specialist relationships with wildlife, our most common plants serve as the backbone of our wild areas supplying food and shelter to a wide range of species. Once this is taken care of and the generalists established, you can always go back and find some niches for the rarer plants that pique your interest!     

High Value Generalist Plants for Every Garden

 

If your garden doesn’t already have many natives, virtually anything you put in there will improve the ecological value. Whether that’s a well-established but mostly exotic garden or an area that used to be lawn, it makes it a bit easier to get started. Choosing generalist species allows you to get started and gives you a foundation to later apply a more plant community-based approach by focusing on species that occur across a wide range of natural communities.  Here we’ve highlighted some easy-to-grow natives that occur across a wide range of habitats that are known to be high value to wildlife.

 

These lists are meant to be short to highlight good starting points rather than exhaustive lists of everything that could do well. We’ve grouped these lists in ways to make them more approachable to the home gardener; maybe you’re looking to plant a canopy tree, or have a sunny garden bed in a wet spot. 

Beginning to Read the Natural Landscape

 

As obvious as it sounds, if we want to restore or attempt to recreate something that resembles a natural landscape, we need to understand what those areas look like. To better understand those areas we can breakdown a landscape in to biotic factors (that is, living components) and abiotic (non-living) factors. In each of those groups, we may or not be able to do anything about them and that will also help steer our planting goals.

           

Plant identification skills will be a critical component of this kind of assessment. It’s not in the scope of this guide to teach plant identification, but high-quality field guides like the Flora of Virginia, Newcomb’s Wildflower Guide and/or The Sibley Guide to Trees will be useful companions. The most critical components to identify are the canopy trees. In our section on Plant Community Plant Selection, we’ve highlighted the species that are representative and diagnostic of those communities so you may want to get acquainted with those species as you begin studying plant identification skills.

           

When assessing the dominant plants on a site, don’t just think about a simple presence or absence but observe how common a species is and whether it’s reaching its maturity or not. A canopy tree species that is only attaining understory tree sizes could tell us a few different things about a site: perhaps conditions are poor for that species, there could be a successional shift from one forest type to another happening, or there could be some disease or pest suppressing that species.

           

In addition to ID skills, observing the characteristics of the site are crucial. Topography, soils, and water (along with climate) are the major drivers of plant communities. Think about these variables and their gradients and transitions across your site: is there a slope, a stream, a transition from deep forest to forest edge? Each of those could influence how species are distributed, and what plant communities are present across a site. For example, expect the top of a slope to be drier than the bottom of a slope where it levels off so you may find moisture-loving shrubs towards the base, and a transition towards more drought-tolerant species at the top.

           

Just as we look at the living components with nuance, we should approach the non-living factors on a site with a similar eye for detail. Think, for example, about where the water in a wet area is coming from. Is there a flowing stream or creek (signifying the presence, perhaps, of an alluvial wetland) or is it a seep or a bog (some kind of non-alluvial wetland), or is water collecting in hard compacted soils after rains? Almost all our soils are clay-heavy, but knowing if they dry out between rains, if it’s rocky and thin or heavy and mucky will tell you more about the site.

Being able to effectively read a site takes time and experience – the more you can compare it to other parks and natural areas you’ve been to and the flora you’ve seen on those sites the more complete a picture you’ll be able to see. Don’t fret if you can’t make sense of everything! People are willing to help – in fact, as time allows, we even do house calls and consultations, but good landscape designers with experience with native plants will have a good sense of this too.

The more comfortable you get identifying the plants and see and understanding the contours of a site, the better you will become at identifying what plant communities we have and where they might be found.

What is a Plant Community?

A plant community is an assemblage of plant species that arises repeatedly in certain conditions. Plant communities can be natural (late successional to old age forests, stable prairies, marshes and various wetlands), semi-natural or successional (for example, successional meadows, old fields, and early successional forests). Where patterns are observed and repeated in similar habitat, ecologists define and delineate out specific plant communities. This is done in a scientific manner where they identify representative areas, select test plots within those areas, and identify and quantify the plant species growing in those plots.

When sampling for plant communities, ecologists refer to two variables, “cover” which is the percent area that a given species takes up in a test plot if viewed from above, and “constancy” which is how frequently a species occurs in all test plots across a given community also given as a percentage. Taken together these can give us a detailed understanding of the landscape. High cover, high constancy species are common and ubiquitous across a landscape, whereas low cover, low constancy species are rare to find and may be solitary or in small colonies when found. High cover, low constancy species may be less commonly found, but create large stands when present, and low cover, high constancy species are frequently found but diffusely spread across a site.

Each plant community is also defined by indicator species and conditions. For example, a “Coastal Plain/Piedmont Small-Stream Floodplain Forest” is defined by the dominance of Tuliptree, Spicebush, Sweetgum, and Jack-in-the-Pulpit on sites with low elevations with typically acidic soils, along small streams in the Coastal Plain and Piedmont in our region.

As detailed a picture as this creates for us, it also requires us to know a fair bit about the landscape and the plants therein to identify the specific plant community on site.

Natural plant communities may intergrade with each other or with successional and semi-natural adjacent to them. For that reason, especially in highly fragmented areas, these transitional areas, or ecotones, may make up a substantial part of the landscape.   

A Word on Forests and Woodlands

This section of the Almanac, on the selection of generalist native plants for gardens, has been given in the spirit of planting out new areas. That is, our assumption is that the gardener is more or less starting fresh and looking to, roughly, recreate some kind of natural habitat where little exists. But what if you wanted to spruce up an area where you already have some kind of forest fragment?

           

When working in forested and woodland areas where there may already be some native plants, or some kind of “ecological memory,” our advice is to slow down, remove stressors from the landscape (see “Good Habits for Good Habitats”), wait and see what regenerates, and then plant more delicately.

           

This is an application of the “first, do no harm” precept we should bring to ecologically-sound gardens and landscape, and mirrors how we and various park managers and ecologists approach restoration on public lands and in natural areas.

           

If you do want to begin by planting, we recommend planting out a buffer area – that is, extend a garden on the edge of the woods and put new natives there. For that, you can use our lists on canopy trees, understory trees and shrubs, and successional shrubs and trees from the above lists. As you get into remnant natural areas, we think the best approach is to begin by understanding your landscape and then planting out in a more specific schema that begins to consider Natural Plant Communities. See the next section for how we would go about doing this.

Common Plant Communities and their Major Constituents

It’s beyond the scope of our humble compendium to cover every major natural plant community you bump into in Northern Virginia – indeed, ecologists at Fairfax County Park Authority identified some four dozen or so communities that can be found in their parks alone! Luckily, just as species are grouped into genera and families, communities have hierarchical groupings too.

           

So, for this Almanac we decided to choose one common plant community type across three ecological classes so we can given in-depth planting guidance using hard data for an upland dry to dry-mesic forest, a low-elevation mesic forest, an alluvial wetland forest, and a non-alluvial wetland forest. If some of those words didn’t make sense, check out the brief glossary inset.

           

We think that this will allow you to get a chance to see detailed plant guidance that is still applicable to gardens and natural areas. We also plan to add similar resources for other plant communities on our website, so if you have an area that you feel isn’t well represented by the four communities we’ve chosen to highlight, check out what we have online! You can also look at our Plant List at the end of the Almanac and read our grower’s notes for each species we intend to have for this year.

 

For each list, we’ve described in general terms some of the traits of the landscape you might observe and the indicator species for the community (whether we grow those or not). For the plant lists, we grouped species by layer (canopy, understory shrub and tree, and herbaceous) and given their constancy and cover, to give you a sense for how frequently and how densely you may want to plant them. For the lists themselves, we’ve only included species we grow ourselves at our Wild Plant Nursery and excluded species that occur with very low constancy (less than 10% of the time). This is both for the sake of brevity (the raw data can include hundreds of species, native and non-native) and because we grow species we believe are good targets for restoration for various reasons (see inset “Why Do We Grow These Plants?”)

Common Plant Communities & Their Constituents Lists: