Round-up time
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WALKING round the Beechgrove Garden the other day, I was making a note of all the jobs to be done at this time of year and the first thing that occurred to me was the poor state of one of the lawns.
In passing, I should add that the main lawn, which wraps round the pond, has been looking absolutely marvellous this year, better than ever before. The one I have in mind is hardly ever mentioned because we are so busy featuring the borders around it, particularly the ‘dry river bed’.
This bit of grass, with a fair amount of clover in it, looks pale and undernourished, despite regular attention. There is no doubt that the problem relates to the soil underneath, or the lack of it to be precise. The other major feature bordering this lawn is the free-standing conservatory that was transferred from the original garden and needless to say there were significant earthworks to make the place ready for that structure.
During the levelling process that followed the completion of the building works, I reckon that the area sown out to grass consisted of a mixture of topsoil, subsoil and the usual detritus from a building site – the odd bit of concrete, a few half bricks, some sand/cement mix that just missed the mixer etc. Does this ring a bell with you perhaps?
In our case, this comes on top of the fact that, when we took over the site, this part of it was terraced and as far as I can see, no one was controlling the distribution of top soil over the newly created areas of flat ground. In other words, we are trying to grow a lawn on a bit of undisturbed, sub-soil levelled off with a shallow layer of a’thing, as already described. No wonder the dry riverbed plants next to it are doing well, they thrive on such conditions.
The question is: can we improve this bit of grass or should we kill it off and start from scratch?
This would be a good time to sow a new lawn but, in my view, we can make the existing lawn look a bit better if we start our renovation programme right now.
This is the time of year for hollow-tine spiking because some test borings showed the underlying soil to be very sandy/gritty but also quite compacted. Hollow tining entails removing narrow plugs of soil about 10cm long with a special tool (for large areas, it pays to hire in a power-driven, pedestrian controlled machine).
Straight away this process allows air and water to penetrate quickly. After the plugs of compacted soil have been swept off, the area can then be top-dressed with a compost mix, containing quite a bit of organic matter. This is brushed or rubbed in all over the surface using the back of an ordinary garden rake and in the process it lightly fills up these cores. The first stage in improving the texture of the growing medium has begun.
Top dressing mixtures can be purchased from well-stocked retailers but if you have some of the raw materials you can make your own. I tend to store up old potting compost and growbag compost for this job because they are a ready source of organic material, which is sieved to a fine consistency. To this I would add some soil from the vegetable patch, so long as it is of a quality that produces good results.
The proportions will depend on the nature of the soil under the lawn. If, like our present case, the soil is light and sandy, I would use a mix containing 60% spent compost and 40% garden loam. If the underlying soil is predominantly clay, I would then be looking at a mix which contained 40% sharp sand, 40% spent compost and 20% loam.
The mix needs to be reasonably dry and free-flowing (put through something like a 5-7mm sieve) and it goes without saying that the surface of the lawn has to be dry when applying the mix. This topdressing mixture can also be used to fill minor indentations or hollows in the lawn.
In the meantime, I think it is about time to raise the cutter blades on the mower, to leave just a little more cover. Next spring, we will start with light scarifying, feeding and regular light cutting but that is a story for another day.
Continuing the walk, I came on a border with Lavatera still flowering quite well and, not far away, the great seed-heads of Buddleia were hard to miss. Neither of these two plants are too strongly rooted and therefore it is customary, after flowering, to cut them down to under a metre high, to prevent windrock. Next spring, they can be trimmed even more severely.
My next stopping place was the CM Baxter Chocolate Border. We had a fair mixture of things in that, some annuals, some perennials, some herbaceous, some woody, some hardy and some not. A real object lesson in a very compact space.
What’s to be done because this border has to be emptied? Well obviously the annuals like the sunflowers and the wonderful Rudbeckias will be consigned to the compost heap when they stop flowering. The non-stop begonias are lifted and are now sitting on a wee bit of staging in one of the glasshouses to allow the foliage to dry off and the tubers to ripen before being put to bed for the winter. Incidentally, I like to sort out the begonias when I can still match up the flowers, keeping each colour separate. This helps when you start to plan your displays for the following year. The half hard Chocolate Cosmos and the Pelargonium with the chocolate stripe on each leaf are to be lifted, tops and roots trimmed before being potted up and held in a frost-free greenhouse over winter. The dahlias are still flowering their heads off so they will be left until they are blackened by the first frosts. I dealt with their treatment a few weeks ago.
There are two herbaceous perennials in the border – a heuchera and a foxglove. Both are certainly worth keeping and now is a perfectly good time to be lifting and transplanting them to fill gaps in other borders.
Finally, we have had a lot of questions about busy lizzies recently. Many plants have, all of a sudden lost their leaves, just as if they had been stripped by caterpillars. It was the subject of discussion with a few chums when we met up at the Glasgow Rose Trials judging at the end of August. Was it a new virus? Maybe seed-borne? Would it decimate plantings every year from now on?
The problem is being caused by a downy mildew. It was reported in one of the commercial horticulture publications that the disease organism is Plasmopara obducens. It first appeared in this country in 2003 and probably came in to this country on seed from the USA.
Much has still to be learned about it. I will keep you posted.
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