Other articles in this issue discuss the benefits of native plant gardening to insects and other animal pollinators. In this piece I’ll focus on some basic principles of native gardening by summarizing several lessons I’ve learned over the past 25 years trying to garden with native plants. In both my own experience and the experiences of many other native gardeners I’ve talked to, I’ve found that many of the frustrations people encounter in gardening with natives come from an incomplete understanding of these species’ biology and ecology in the wild. So here are some lessons I’ve learned trying to bring our wild ecosystems home:

 

1. Just because a plant is native to Arkansas doesn’t mean it will do well anywhere it gets planted.
When humans first arrived to what is now Arkansas, they found nearly the entire land area covered with native plants. This simple fact underscores one of the many beauties of gardening with natives: there is a perfect species for every conceivable site. From the driest, hottest, most exposed south-facing rock outcrop to the darkest, wettest forested swamp there are native plants that are perfectly at home in even the most difficult spaces you want to fill. The trick is to match the right plants with the site, and to do this you can look to our wild natural ecosystems for advice.

My personal approach to gardening, which I like to sum up as “maximum biodiversity with minimal effort” centers around this idea of matching species and sites. I recommend studying a prospective garden site for a little while, trying to determine the original natural community that would have been present there historically, and looking to intact examples of that natural community for inspiration. For example, in my yard, which occurs on a dry, rocky shale and sandstone ridge in the Ouachita Mountains with a canopy of post oak, shortleaf pine, and blackjack oak, I know that the native light-loving species of the poor acid soils of dry oak-pine woodlands and glades of the region will be at home on my site.  By contrast, in the rich, fertile soil of a shaded forest site on a north slope or along a stream, I know that shade tolerant spring ephemeral forest wildflowers will do well but the natural conditions needed by the dry woodland and glade flora just don’t occur.

It’s when gardeners try to cross over these natural ecological boundaries in the landscape, that they are likely to run into trouble. It’s not that it can’t be done, but if you want success, accommodations will have to be made. For example, in order to grow forest spring ephemerals at my house I had to find the shadiest sites on the north side of the house, amend the poor soil, and install drip irrigation.


2. Just because a plant is native doesn’t mean it will do well or look good in your garden without supplemental water during dry periods.
Some people have the idea that because a plant is native it will not need any care at all. This may be true in cases of well-established plants that are a perfect match to a site, but a little tending will generally get you better results. Even drought-tolerant plants need some water, and this is especially true of young perennial plants that are getting established. Also, just because a plant will survive on a site doesn’t mean it will thrive, flower, or look good. It’s also true that when species that are the most at home in semi-shaded woodland conditions get planted in full sun, they will need more water than they do in the woodland. Think of the survival of each plant as a tug-of-war between moisture available at the roots and water loss through the leaves. The more a plant is exposed to the drying effects of the sun, the more moisture it will need to stay hydrated and be able to fully function. And it is the extremes of drought that kill plants, not the average daily or weekly or monthly moisture levels. It just takes one episode of extreme drought stress to lose a plant for good, and the drier your site, the more plants will need to be monitored for signs of drought stress.


3. Some natives are “too happy” in the garden. 
Another common frustration I hear from gardeners is that many native species grow too tall (often twice as tall as expected or desired) and flop over in the garden. In general, these are sun-loving species adapted to poor, infertile soils, and they occur in the wild in tight competition with others so that nutrients, water, and space are all scarce. When these same species get planted in fertile garden soil, are well-watered, and have the competition weeded out, they tend to grow bigger than expected. If plants native to these sorts of sites (for example, pale purple coneflower, Echinacea pallida) are being considered, the soil should not be amended. These plants really do like poor rocky/clayey/sandy soil with little organic matter. Resist the urge to coddle these kinds of natives with good soil!


4. Just because a plant is native doesn’t mean it will be well-behaved and play nice with others.
Native species can be invasive, and especially so in the garden. Not all plants are alike, and even within a genus different species may have evolved different life strategies, with some being naturally aggressive and weedy. A good example is the goldenrods (genus Solidago). We have more than 30 native goldenrods in Arkansas, and these range in habit from the rare and well-behaved clump forming Gattinger’s goldenrod (Solidago gattingeri) to the rank and downright invasive tall goldenrod (Solidago altissima), which grows tall and spreads rapidly underground to form huge colonies. I recommend against inviting it into the garden (though it will almost certainly arrive on its own at some point, as it is also a prolific seeder and colonizer). 

Many of these “native invasives” share common traits like rapid growth or a rhizomatous growth habit (forming a colony from creeping horizontal underground stems). If you have a small garden, you might avoid these more aggressive rhizomatous species altogether, or at least know that you will probably need to control their spread if you want to have anything else. Another good example of a large genus with both well-behaved and invasive members is the milkweeds (genus Asclepias). On the one hand there is the horsetail milkweed (Asclepias verticillata), which maintains long term as a tidy clump, and on the other there is the common milkweed (Asclepias syriaca) which can make a tall dense colony with thousands of stems and out-compete all other plants nearby.


5. Most natives take a little effort and understanding to grow from seed.
Another common frustration I hear expressed from people is that they spread out some native seed and nothing ever came up. Often there are three things going on: 1) an incomplete understanding of seed ecology, 2) insufficient site preparation and maintenance, and 3) impatience.

Native Seed Ecology

Most native plants, especially wildflowers, that people desire in the garden have seeds that require some sort of treatment in order to break dormancy and germinate. There are several different types of seed dormancy, but all of these are natural adaptations that ensure that the seeds will germinate at a time when the resulting seedlings have the best chance of survival. The most common type of dormancy occurs in seed that needs to go through a period of cool, moist conditions to germinate. In replicating this treatment, we are essentially tricking the seeds into thinking they’ve just been through the winter in the ground. Germination in the early spring ensures that the seedlings will have a period of adequate temperature, moisture, and light to get big enough to survive the coming summer. As a gardener, you can sow these seeds in the fall as nature does or put them in a baggie of moist sand (not too wet!) in the refrigerator for a period of time before sowing them (the exact length of time depends on the species but generally ranges from three months to 10 days). Even after this period of “cold moist stratification,” most seeds won’t germinate until soil temperatures reach a certain level, signaling to the seed that the danger of a hard freeze has passed.

Seeds of some species have a hard, protective seed coat that needs to be physically broken in order for the seed to soak up water and break dormancy. In the wild this may happen as the seed passes through the digestive tract of a bird or other animal. A gardener can replicate this by gently rubbing these seeds with sandpaper or nicking the seed coat with a knife before sowing. Some seeds, including many of the beans and peas, can be nicked but will also break dormancy after pouring boiling water over them and allowing them to soak for a day or two.

Seeds of some species require exposure to certain chemical compounds to break dormancy. In some species, including many wetland plants, ethylene (given off by ripening fruit or decaying vegetation) is the trigger. Many species native to fire-adapted ecosystems have evolved to germinate after a fire removes competing vegetation, and these seeds germinate in higher percentages after being exposed to chemicals in smoke and ash. Some gardeners, myself included, have had success by making “smoke tea” (by forcing smoke from burning vegetation to bubble up through water) to treat seeds of these types of plants.

Another common misconception among gardeners is that seeds of native species must be buried in order to germinate. This is actually an uncommon requirement and is most often found in larger seeds (like oaks and hickories) that are planted by mammals like squirrels. Seeds of most natives do well on the surface of the soil or only lightly covered. Seeds of many grassland and open wetland species, especially those with very small seeds, need light in order to germinate and must be sown on the surface of the soil. 

Seeds of many native forest species, including many spring ephemeral wildflowers, have a double dormancy, requiring a period of warm, moist stratification followed by a period of cold, moist stratification. Some even require a second period of warm, moist stratification or even several years in the ground.

Site Preparation and Maintenance

Another common cause of failure in planting native seed is inadequate site preparation and maintenance. Seeds need good contact with the soil to successfully germinate and become established. Attempts to sow seed in established stands of dense grass or on top of dense leaf litter are not likely to do well. In the wild, many species establish new generations from seed in the year following a fire or flood or some other disturbance that makes the bare surface of the soil available to seed. The same conditions are required when establishing a native planting.  Also, if you are establishing a native meadow or prairie from seed, the site may need to be prepared by treating the existing vegetation (with herbicide or some other method) for at least a year before planting. Maintenance in the years following planting is also critical, with periodic mowing recommended several times during the first and sometimes second year (so young seedlings can compete with more rapidly growing, taller weeds) and annual burning or mowing after the growing season in the years after that.

Patience

It will likely take three years for slow-growing native perennials to recruit from tiny seedlings to mature flowering plants (and longer for some species).  An experienced practitioner of such prairie restoration once told me “Patience is key with a perennial prairie planting like this. It will take three years to really see the results. The first year it sleeps, the second year it creeps, but the third year it leaps.” 

 

Photos:

Photo 1 — This open woodland garden around an old post oak tree in Little Rock was planted with dozens of species native to the dry post oak-shortleaf pine woodlands present on the site before a neighborhood was developed there in the 1960s. Once established it has required little care beyond occasional watering during dry periods and an annual clean-up. Photo by Theo Witsell.

Photo 2 — This mesic forest garden with dozens of spring ephemeral wildflowers is on the same site as the dry woodland bed but required careful site selection (finding spots with maximum shade), soil amendments to increase fertility and water retention, application of shredded leaf mulch, and regular irrigation during the sumer and fall. Photo by Theo Witsell.

Photo 3 — This rock garden on a very dry, exposed south-facing driveway cut was designed to mimic sandstone and shale glades found nearby and includes dozens of drought-adapted perennial wildflowers, shrubs, and grasses. Aside from occasional watering to keep the plants looking good it needs only an annual clean-up for maintenance. Photo by Theo Witsell.

Photo 4 — This colony of the native hairy woodland sunflower (Helianthus hirsutus) first appeared as a single stem at the base of two post oaks in a zoysia grass lawn – the sole survivor (aside from the oaks) of the natural woodland that was there before the neighborhood. It was the inspiration for an entire bed of “local natives” likely present on the site historically. It has slowly spread over 7 or 8 years to form a nice colony that helps sustain a diverse pollinator community. Photo by Theo Witsell.