The Smallest Gardens
- Miniature gardens can be very satisfying elements within the small personal landscapes that many of us inhabit.
Hypertufa and stone troughs and pots are very versatile planting containers, remaining in place outdoors through all the seasons, and lasting for many years. After a while, when in touch with the earth’s surface and organic materials, hypertufa containers gradually green up and come to resemble local fieldstone in color and character. Perhaps the nicest compliment mine have ever recieved is that “they look like G-d made them”.
- Certain kinds of plants, many of which are choice and beautiful, will return on their own year after year within these containers, without any protection in winter. There are a lot of perennial plants which, it turns out, are preadapted to the kind of life one can have in a trough in New England.
Floriferous annual plants and quite a few useful herbs also thrive in these confines, so there are many choices of how to use these small habitats in your place.
- Hypertufa is a man-made material which is so named because it imitates natural lime laden, porous Tufa rock in chemistry and in physical properties. Many kinds of plants will grow well in the environs of either one.
If you are very fortunate, an old stone sink or a horse trough may turn up. Such things as these also can make ideal small garden beds, but are very hard to come by. I would start with hypertufa containers, but remain optimistic for the future. It is likely that you may want more than one trough once you get started.
- When you are choosing the plants, if you will be having multiple varieties in a single container, it will be important to find kinds which share similar biological needs since they will share this small ecotome. The little gardens also will usually look best, and be most easily kept, if the companions are chosen to be similar in scale and speed of growth.
- For easy sustainability, the trick is to choose appropriate plants for the ecological circumstances you can offer. When the troughs are planted to suit the place where they are sited, they never have to move.
The tending maintenance of well planted and considerately sited containers can be very minimal.
Siting Trough Gardens : Zone 5
- Basically, these are self-contained ‘raised beds’. You can choose to keep them at a heights which allow you to easily see, touch and tend the residents. A stone wall may provide an ideal place to site them, but they can be set up on a sturdy shelf, or any available structure that can support their weight.
Located by design in places where you can get near to them, each trough can become a whole landscape picture, filling your close view.
- The troughs allow their chosen occupants to avoid competition from other plant materials. Such miniature gardens can therefore be especially enhancing when sited under trees. With freshly beautiful colonies settled safely in their special ‘beds’, they can ornament rooty places where, otherwise, not many things could manage to grow.
- It is perfect when, in their chosen locations, your containers get lightly watered automatically by in-ground irrigation, if you can arrange it. Even if you do, it is advisable to select sites where you can easily provide a little custom watering sometimes. Being small in volume, containers lose their moisture more quickly than earth places do. They don’t need a lot of water, but they need it regularly.
- Locating your troughs where there is some shade in the hottest times of day will make things easier to manage. Too much sun may cause the containers to heat up and dry out too fast, even for sun tolerant plants.
- Hypertufa troughs and pots can be made in a great variety of shapes and sizes, custom to whatever your spatial needs may be. If you have the ambition and a largish place to make a one month long outdoor mess, you can create your own containers if you wish to.
Basically, the material is composed of a simple mixture of cement, perlite and/or very course sand, strained peat moss and water, whose proportions vary somewhat depending on whose recipe you use. When thoroughly moist, the composite material is simply pressed into a shape with a form or over sand, then allowed to set for a span of days in a shady place. The mixture will be stronger if it cures slowly, so it is kept covered in plastic sheeting.
Although I may take the container off of its mold after a few days to use a wire brush or file on it for shaping and/or texturing before it sets up fully, after this touch up, I turn it upside down again in its curing place, re-cover it with the plastic, and give it a few weeks to sit quietly. At this point I turn it right side up and let it get rained on for a few more weeks, then it is ready to use.
- An exemplary article by Helen Dawson about making hypertufa containers, with images showing the details of the process, was recently presented by Fine Gardening (.com). The recommendations nearly match the recipes and procedures that I have used, except that I have not added fiberglass. I hope that you will look at her excellent instructions if you plan to do this yourself.
The only additional details in method I might mention would be that I use type 2 Portland cement because it gives a deeper grey color, and I use less perlite and add some very course sand. This way I end up with fewer ‘white dots’ of perlite and so perhaps a more naturalistic appearance overall, but the sand adds a bit of weight to the structure.
I like the walls to be at least 1 1/2″ thick, and in large containers, 2″ is good.
When you cast upside down over a sand mold, it may also be nice if you can make a moat shape in a soft ‘base’ pad of sand where the lip of the container will be formed, so when you eventually turn it right side up, you will have a softly rounded rather than a flat upper edge on your container.
I have made quite a few of these over time, but for the larger ones, I usually give the project over to a professional. Well constructed troughs and pots have typically lasted 15 years and more in my landscapes.
Considerations of Shape and Size
- In my experience, the most versatile troughs are 12 to 18″ wide and 20”+ long with an interior depth of 7” or more. I find my most popular shapes are a foot or so wide and 20″ to 36″ long, probably because those sizes sit nicely on many commonly available surfaces. A rough minimum for sustaining perennial plants over time would be an interior depth of 6”, with a 10” width or diameter.
- Whether you choose perennials or annuals, good surface and bottom drainage will be essential.
A fine ¼” stone mulch at the surface is often ideal. This also makes a receptive seedbed for your chosen things to seed into their home grounds.
For Alpine plants, drainage is extremely important. Many Alpine plants are preadapted to the settings these containers can provide, but often they can’t withstand wet crowns for long, and so must drain quickly when the snows or rains impinge. To this end, I embank the earth in the overall container so as to create a slope gently descending outward from the center . I sometimes use stones in a few places to support this banked presentation to the view.
Choosing your Trough Shape
- In general, more kinds of plants can be sustained through the winters in larger containers than in small ones. Wide and deep containers provide more earth around the plants, which seems to help cushion the extremes of our New England weather.
- For colonies of things, bigger is also better. It is just that there is more room for your various kinds of plants to develop gracefully into meaningful colonies within your miniature gardens. Whenever the container is big enough, it may be esthetically interesting to give it dominant and subsidiary plants, perhaps choosing ones that flower in various times of year, just as you might if you were organising a larger landscape, on a smaller scale.….
Earth for Sustainable Planters
- I always mix perlite and ¼” stone into the planting substrates to help keep the mix perpetually free draining. I add some slow release fertiliser too. Depending on who you will be growing, what else you use in the container to make up your planting ‘earth’ can be adjusted somewhat. Your proposed plants may prefer more or less lime. Some kinds like lean earth and others prefer theirs to be organically rich. When the plants are generalists, they are easily kept, and there is usually nothing very exact about the mixtures.
There are even some easy Alpine plants. There are fussier ones too, requiring particular care and special ingredients in the mix, but I usually choose the adaptable varieties.
In the end, you will know if things are fine by the apparent well being of your plant materials.
If you need to add more earth or ingredients later, or you want to adjust the pitch of the container’s surface, so as not to disturb the colonies too much, you can work a trowel in underneath the plants, lift the planted group, and tuck in extra substrate below.…
- For clues about the best substrate for your planter, you may want to Google your candidate Plants’ names to read about their original and preferred habitats. The North American Rock Garden Societyhas been helping people (including myself) to grow plants in rock gardens and troughs for a great many years. If you have alot of questions, you might want to join the Society for a while. They have local chapters under whose auspices you can see and learn alot, and they will help you to locate plants that might be hard to find on your own. The level of knowledge within their membership is beyond amazing, and always has been.
- Certain particularly durable perennial things can even manage through the winters in very small troughs or pots. Like their full size Hosta relatives, most miniature Hostas are tough enough for just about anything, as long as you avoid hot and sunny places.
For a small or medium alpine trough with partial days of sun, the encrusted silver Saxifrages are an essential group, and fortunately some are very reliable. Many are fully evergreen, and they thrive with the bit of lime hypertufa provides. S. callosa (lingulata), S. cotyledon and S. longifolia in variety have proved especially adaptable. Saxifraga apiculata, which is the first to bloom in spring, has returned here for 15 years.
In shadier places, Saxifraga cuneifolia and S. umbrosa x urbium, in both their green and their yellow variegated forms, are particularly willing and able.
- Little containers can easily be placed in a wind protected place for the cold season, but I rarely find that I need to, if the occupants were chosen for their resiliency.
- The most important size consideration for the non-hardy decorative annual plants you choose may be that they are in scale with their container for good appearance. Nomatter what size of container they live in, most of them will need some liquid fertiliser every couple of weeks.
Some Easy Perennials
- The ever flowering Corydalis lutea and C. lutea alba, the indefatiguable Kenilworth Ivy including a new pure white form, Cymbalaria alba compacta, Linaria Canon Went and the tiny Thalictrum kiusianum will be readily pleased in these semi sunny places, just to name a few of the easiest and longest blooming candidates.
….latives of the Japanese painted fern…….
- I find that containers in hot sun are the most difficult to sustain, but even there, the simple but beautiful Hieracium pilosella will enthusiastically decorate a container forever, though often too aggressive for much companion planting. The flowers are modest but my, what lovely silvery foliage it has..
Special Uses for Hypertufa Troughs and Pots
- When you have just one or two of something special, keeping these ‘parent’ plants in troughs or other permanent containers allows them to be protected and watched over until the time when they begin to self sow or are divisible.
- If you locate a trough in a setting which has an inviting ecology for seeds, and you leave the ground around your container undisturbed, next year you may have babies appearing on their own. Many of the Zone 5 hardy annuals and perennials suggested in my articles will happily sow themselves in.
- After a couple of years, when you have quite a few of your chosen kind established, you can put some of them in the open garden and feel safe.
- You could decide to let only one beautiful kind of plant completely occupy a trough or pot, in which case the planting is a monoculture. With this method there is no risk of losing your unique kind of plant to other competing colonists. I keep a lot of very lovely containers this way, letting one particular kind of plant thrive and show well. These are perhaps the easiest kind of containers of all to manage.
Mixed Colonies of Plants, some Admonishments
- If there are multiple kinds of plants within a trough, without intervention, there will probably be winners and losers. As the mixed colonies develop, there will invariably need to be decisions about who has priority over whom.
Certain plants can co-compete somewhat equally, but other types can easily lose their ‘ground’ to rootier or otherwise more vigorous things. If rambunctious plants land themselves in your troughs, you can’t let them stay or your other precious denizens can quickly be crowded out.
- For each trough I simply establish rules of who gets to stay and who will be subtracted, and then try to keep to them. To be a good gardener, one has to learn to be a bit ruthless.
- In winter, outlined in snow, the trough shapes show their sculptural qualities, and I treasure them for this too. They seem such protective places as I think of their sleeping inhabitants.