Natives in Pots

There are many reasons to grow outdoor plants in containers. You may not have space in the ground, or they can be used as decorations on a deck or patio, or you may just want to bring the plants closer to where the people are. The main reason I have been growing native plants in pots is that I do not have the right growing conditions in the ground to raise the the plants I want from seed. This is particularly the case for annuals from some of the hotter parts of the country.

Here are some of the plants that I am growing this year. Lantana, Lantana camara, is technically a North American native, since its native range includes Mexico and Puerto Rico. It behaves well as a bedding or potted plant in colder climates, but it is invasive in the warmer parts of the US, particularly Florida and Texas. I really love the red-orange-yellow multi-colored flowers and long blooming period.  These I bought from a nursery and mixed in with other classic annuals like the Lobelia, shown here.  The rest of the annuals I have grown from seed.

While on a trip to Austin, TX, I picked up seeds for Drummond phlox, Phlox drummondii, and the annual Indian Blanket, Gaillardia pulchella, at the Lady Bird Johnson Wildflower Center. These appeared to be species plants and not any crazy cultivars. So far the Phlox has made it to bloom, with its scarlet red flower. The Indian blanket is just a week or so away. Another Texas native I have growing in pots and in the ground is Scarlet Sage, Salvia coccinea. None of these plants really started growing until the temps here got well into the 80’s.

I was really happy to see that some seed from the Beach Sunflower, Helianthus debilis ‘Pan’, that I grew last year had germinated in the same pot. Native to the Texas coast, this species has spread up the East Coast all the way to Maine. Here it is in bloom last year in the same pot. I have also grown Bearded Beggarticks (Bidens aristosa) in pots. Given half a chance, this eastern native reseeds itself readily.

Some native annuals that I had in pots last year are Devil’s Claw (Proboscidea louisianica), Yellowdicks (Helenium amarum ‘Dakota Gold’), and Bird’s Eye Gilia (Gilia tricolor).

The native perennial that I have in a pot is the Crimson-eyed Rosemallow, Hibiscus moscheutos, that I bought from the New England Wildflower Society. While it is native to New England, I just don’t have the sunny moist site it would like to keep it in. I over-wintered this in its pot by storing in a plastic bag with salt marsh hay in an unheated garage. It looks pretty happy so far. The blooms are expected in late summer.

Rock Harlequin, a Native Corydalis

I first ran across Rock Harlequin, Corydalis sempervirens, while climbing around a rocky slope when I noticed the pink and yellow flowers poking up out of a crack in the rocks. It seemed so odd that such delicate flowers would be in such a seemingly harsh habitat. In fact these plants do very well in harsh conditions like exposed stone walls and shallow, dry soil conditions, but it does not like too much heat. Other common names for this plant are Pale Corydalis and Tall Corydalis. I like the Rock Harlequin name, since for me it pop out of the rocks like some kind of joker.

Its native range is all across Canada and south from Minnesota over to Georgia (in the higher elevations). C. sempervirens is found in throughout Massachusetts, excepting Barnstable County and the Islands. Its native habitat is in dry or rocky woods and often on sites after a disturbance.

It seems as if it can deal with poor soil better than it can handle competition with other plants on a richer site. This was borne out in my garden when I put a few plants on the edge of a mass of Yellow Corydalis , C. leutea, in cool moist soil. The Yellow Corydalis completely engulfed the Rock Harlequin within 2 weeks, never again to be seen. I had much better luck on a dry site on the edge of the driveway where not much else would grow.

Corydalis sempervirens is not so much an annual as it is a biennial or short lived perennial, producing a large amount of seed and moving around the garden. Like an annual it will flower in its first year from seed. The highly dissected gray-green leaves occur all along the upright, branched stem. The ¾ inch long pink and yellow tubular flowers are borne in panicles at the ends of the foot-long branches. Blooming time begins as early as May, for year old plants, and continues sporadically though September.

Fresh seed, or seed kept cool and moist, are best for starting this plant. Seed started indoors should be moist stratified for 60 days and then be planted shallowly as light is needed for germination. Seeds are available from a few sources, including Summer Hill Seeds. I have started two batches of seeds with excellent results, high rates of germination and strong seedlings.

This year I started seed, before I figured out if I had a place to put the new plants, since space around the garden is filling up. Then I remembered where I first saw the plants, so I put a little soil in the cracks in a garden wall (over a layer of landscape fabric) and stuffed in a few plants. After a few days they seem to be adapting to their new home. With any luck they should be blooming in a couple of weeks.

For more information on this plant check out this link to the Wildflower Center's Database.

Dealing with Cultivars and Clones, something to consider for Wildlife Gardeners: A Garden GOOPS

It’s not exactly the first of the month, but it is my first posting written in June, so Joene asked me to share some of my garden GOOPS (see Joene's Garden Oops). Just in the past week the following situation came to light and I would say it qualifies as a GOOP.

A few years ago I bought 2 Viburnum nudum ‘Winterthur’ for the attractive summer and fall foliage and the promise of multicolored berries turning into treats for the birds. So far I have not seen more than 1 or 2 sad little berries. What I learned recently (pointed out by Ellen at Turkey Hill Brook Farm) was that many Viburnums, including V. nudum are self-sterile. This means to get viable fruit it needs a pollen source that is genetically dissimilar but from the same (or compatible) species. So in my case a different cultivar of V. nudum, or the straight species will be in order. As luck would have it, I found a species form just the other day, so I snapped it up. Now I just have to find a nearby place for it.

This situation is better known when dealing with blueberries, where at least 2 genetically distinct cultivars, with similar bloom times, are planted in proximity in order to get a good yield of fruit. Since many blueberries are labeled as early-, mid- or late-season blooming selections, it is easier to match up the right plants.

For the garden planner, a similar situation occurs with plants that are dioecious, that is, having male and female flowers on separate plants. This is well known with hollies. Since the red berries on the female plants of many hollies are an important attribute, male counterparts for each of the female cultivars have been identified with similar bloom times.

Most cultivars are reproduced by some asexual means, be it cuttings, grafts, divisions or tissue culture. This ensures that every plant you get performs the same, since they are all genetically equivalent. What you get with a such a cultivar is consistency and reliability of performance. This includes size and shape, bloom time and color, as well as disease resistance. For edible plants, like apples and blueberries, you could include properties of the produce, like size and taste. From a design point of view cultivars can make a more effective composition where consistent size and color are important factors. Also the reduced fertility of some cultivars means you don’t have to deal with ‘nuisance’ seedlings and squishy fruits. 

Even plants that are not labeled as cultivars may have been reproduced asexually.  It is much faster to grow a mature plant by cuttings and divisions, than it is from seed, but there are consequences.  What you lose with these genetically identical plants is diversity. Over a series of generations, if the plants can reproduce, you decrease the gene pool and the ability of the population to adapt to change.

In working with plants that are introductions, not native to an area, this reduced fertility can be seen as a way of reducing the invasive potential of this new plant in the environment. For example, for many years the Bradford pear was a sterile clone. Even overused as it was, it did not spread by natural means. Recent cultivars, with improved branch strength over earlier forms, have inadvertently developed increased fertility which may set the stage for an invasion.

For the gardener who wants to maximize the diversity and wildlife value of their gardens by producing fruits and viable seeds, knowing which plants are dioicous (separate male and female plants) and which are self-sterile will be an important guide in the selection of plant materials. For those lucky enough to be living near wild populations, or having neighbors with similar, but genetically distinct, plantings there may be diversity enough. However for the isolated wildlife gardener, surrounded by a suburban monoculture of lawns and Bradford pears, you may be on your own in creating your own ark of diversity. I am always one the lookout for seed-grown plants and open-pollinated seeds as a means of broadening your local gene pool.

If you like like to read more on Viburnum pollination, check out the discussion at Dave's Garden.