Just at the moment I am somewhat fed up with mixed borders, or mixed beds for that matter. I am of the opinion that it is a myth that the mixed border is easier to maintain than the herbaceous border. It is easier to leave alone, but not to maintain.
The mixed border is a term coined to describe plantings which are typically a blend of small shrubs, perennials and annuals all frothing together to create a picture of flowers and foliage. It is pretty much how most people garden, certainly in freshly planted situations. The woody shrubs give year round structure often with the bonus of seasonal flowering while the clumping perennials and showy annuals fill in the spaces between and give a well furnished look, usually with the attribute of prolonged flowering. The calibre of the plant combinations speaks volumes about the skill and experience of the gardener.
This is also the face of the modern rose garden. Gone are the designated rose beds where there were only roses planted in well cultivated but bare soil with plenty of air movement – utility, lacking in aesthetics but a practical approach to growing these thorny, disease prone plants with fantastic flowers. Nowadays we generally integrate roses into mixed plantings which have a fair debt in history to the chocolate box English cottage garden. Most rose plants are not attractive in their own right so the mixed plantings mask the ugly bushes and, commonly, the diseased foliage while allowing the flowers to star.
So you plant a mixed border or bed and it looks perhaps a little new and bare in its first year, good in its second year, possibly even fantastic in its third year and then, imperceptibly, season by season, it changes over the subsequent years to the point it all becomes a little blah. The woody plants grow and start to dominate while at the lower level, it is survival of the fittest amongst the perennials. Anything rare or choice is by definition not a plant thug so will give up the fight and disappear quickly. Besides, the establishment of the woody plants is likely to have changed the micro climate and that will be compounded exponentially if you also enclosed your bed or border in a nice little hedge. Soon the well cultivated, freshly dug soil and open, airy, sunny conditions that your perennials loved has become compacted and congested with competing root masses from the woody plants, not to mention growing areas of shade.
This is the voice of experience here. I have been micro gardening the area we loosely refer to as the rose garden. By micro gardening, I mean taking apart as much as I can of the whole area and reassessing the role of every single plant. Because we also garden extensively with bulbs, there are limited times of the year when we can take apart a garden to recultivate and replant in this manner. As well as the roses, I had planted dwarf camellias for winter interest and all year round form and the site demanded a carpet of low growing perennials and annuals below. Said carpet had been looking a little moth eaten for some time – too many holes I had attempted to plug (or darn). In fact it all looked rather tired and messy. Successive applications of mulch had raised the soil levels above the surrounding edgings, compounded by the escalating invasion of masses of fine roots from an avenue of huge trees some distance away.
I am so over roses. Every time I turn around or move, I seem to get snagged on their thorns. There are times this week when I have contemplated pulling out and burning all but the standard roses. It is only the memory of their stunning November display that has given them a stay of execution. That, and the feeling that a complete garden includes at least some roses. I certainly will not be wanting to use roses extensively in any future mixed plantings.
Painful irritant though the roses are, they are not the major problem of the mixed border. It is what goes on below the ground that is the inherent structural weakness of the concept. We only view what happens above the ground but that is entirely contingent on the roots below. And the problem is that perennials and annuals are not particularly compatible with many woody plants. The latter determinedly extend their roots and prefer to be left undisturbed. In fact they can get downright touchy if you do too much poking around in their root zone. Whereas clumping plants like perennials and indeed all annuals much prefer extremely well cultivated, friable soil along frequent lifting and dividing of the former. Long term they are mutually exclusive plant families and it is the permanent roots of the woody plants which will dominate. In fact, the mixed border concept is a garden solution for the short to mid term only. In the long term, the bottom story planting of perennials goes into decline, only the tough thugs survive and it gets increasingly difficult to maintain suitable conditions even for them.
The classic herbaceous border is seen as extremely labour intensive and accordingly admired but shunned by most gardeners in this day and age when we lack legions of loyal, hardworking, devoted minions to do our bidding in the garden. Herbaceous plants are those leafy, clumping plants without woody stems and trunks and they tend to be seasonal. In fact many, such as hostas and asters, go dormant and disappear over winter. As I micro garden our mixed plantings in the rose garden area, I am thinking to myself that the digging, dividing and replanting that is the key to a good herbaceous border is not necessarily to be feared and it would be a great deal easier if there were no woody plants (and definitely no roses) in amongst them. No bulbs either. There are other places in the garden for bulbs but they don’t exist that happily in areas where you are forever plunging the spade into the soil to keep it friable and to lift plants for dividing. I have stumbled on rather too many by severing them in half.
Using hedges as a backdrop or as an edging is also problematic. At Great Dixter in the south east of England, Christopher Lloyd paid tribute to his father’s foresight in establishing a solid barrier below ground at the time when he planted the yews which are now major topiary features and hedging in that garden. It is more likely that Lloyd Senior had a man in to do it, but such long term vision stops the problem of competing roots. This sort of below ground barrier is recommended when planting invasive bamboos but I have not seen it done as a matter of course in this country with hedges. It makes sense if you garden with a long term view in mind even if it requires considerable effort in the establishment stages. You need to make sure that the barrier is far enough away to allow the hedge roots sufficient space or you will end up with poor, stunted and yellowed specimens.
If you want to reduce the amount of maintenance your garden requires to keep it looking good, turn to the shrubbery concept in preference to the mixed border and reconsider the role played by dinky little edging hedges beloved by gardeners throughout the country. What these do is give a sharp line, a definition which can also be achieved by the use of pavers, hard edges or even a low wall. None of these alternatives will cause problems with their roots, require clipping or suffer from the dreaded buxus blight.