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A Northumberland Alpine Gardener's Diary

This entry: 19 July 2015 by John Richards

Northumberland Diary. Entry 302.

Compost beds

This may seem like indecent haste, but I haven't commented on the garden for more than a month, and a lot of water has fallen from the sky, not to mention plants that have come and gone, so it is high time I caught up.

At the end of the spring, late May or so, disaster befell two of our well-loved trees. A huge laburnum that was about a century old and dated back to the big house in whose grounds our house was built, suffered heavy winds while bearing a huge crop of flowers and developed a fatal crack and lean. In fact this was no surprise as half the tree had already been lost to an earlier gale a couple of years ago, and when tidying it up previously, our tree surgeon commented that it was merely a matter of time before the rest went.

Also, our Acer crataegifolium 'Variegatum', a much prized present from the late Viscount Ridley, has been showing increasing signs of stress over the years. This spring it became clear as it leafed that over half the branches had not survived the winter, so it had become very unsightly. This small tree was within my own capabilities, and it was soon disposed of. The cause of its demise is uncertain. I suspected honey fungus, but could detect none of the usual symptoms.

Every cloud has a silver lining, and in a mature garden every tragedy provides an opportunity. My technique on these occasions is very simple. I dig the area over, removing roots and, hopefully, all perennial weeds, and then empty a compost heap (sometimes mixed with rotted leaf mould) over the space. Luckily I had a whole heap ready for disposal, and 15 barrowloads were dispersed between the two areas.

After a few weeks to settle, quite a few seedling Meconopsis and Primula from this years sowings were ready to plant out. They love this rich soil, and the following two pictures, taken about four weeks apart, give some idea how things have developed in the acer bed.

Compost beds

The next photo shows the laburnum bed which has been planted with meconopsis alone so far. This also shws the main snag associated with this technique, which is that I never make compost hot enough to kill annual weed seedlings which soon form a small forest, of, chickweed mostly. I hand-pull some of this, and where I can be sure that the mecs won't be affected, use weedkiller sprays, but it mostly gets kocked back by autumn frosts anyway.

Plants in pots outside

There is another simple technique which I have found successful which may be worth discussing. I grow a lot of plants which I don't want to risk in, or consign to, the open garden, but which are unhappy under glass, particularly in the summer. Probably a useful way of dealing with these is to use plunge beds and frames for the pots, but for whatever reason I have never gone down this route, perhaps because there is nowhere obvious to put them in this rather sheltered and shady garden, with vistas which do not welcome the introduction of intrusive paraphenalia.

Increasingly, this has encouraged me to grow plants in black plastic pots which are stood outside for nine months, and then spend November to March on the floor of an alpine house. I have found there are two key elements to this procedure. One is to repot regularly using a proprietary mix with about 50% by bulk of perlite. This stops the compost becoming 'claggy', and the composts used seem to run out of nutrient after about a year. The second is to find the right place to leave the pots. This should have a gravel base (no worms and fewer slugs), and the pot should receive little if any direct sunlight, while the plant receives a fair admixture of dappled light.

The next picture shows how I grow a collection of autumn gentians this way. The pots lie below the level of the terrace, while the plants are in full light.

Plants in pots outside

Of course, if the pots are clustered together, this also allows the sides of most pots to be protected from direct sunlight. There is no doubt that sun on the sides of the pots tends to 'cook' the roots in the most undesirable way.

Meconopsis, primulas, corydalis and the like in pots are grown in rather less light, in a position where they receive early morning sun and then very little thereafter. Part of the skill is to juggle the pots to ones assessment of the individual requirements of each plant. I think amounts of sunlight, and the humidity around the leaves are absolutely vital to the contentment of Himalayan subjects such as these.

Plants on the terrace bed

Here first is a vew of the terrace taken a few days ago. It is astonishing in this late season that there are still candelabra primulas and dactylorhizas in bloom.

Plants on the terrace bed

Saxifraga cotyledon, in its Norwegian form, is such a satisfactory plant. It makes a display to equal that of S. longifolia, but makes side rosettes which may go on to flower the next year, and sets masses of seed too. What more could one ask?

Saxifraga cotyledon

Directly above the saxifrage, on a stony raised bed, grows an excellent Moltkia petraea. This is one of several seedlings raised, but greatly superior to the others. It has a long flowering period, quite late in the season, and is a lovely gentian-blue.

Moltkia petraea

Another reliable blue, but thriving in partial shade, is also long-flowering, the excellent Corydalis omeiensis, the easiest of all the blue corydalis here.

Corydalis omeiensis

Never make a dierama out of a crisis! This garden is slowly getting its dieramas back again after a couple of hard winters earlier in the decade. Here is one of the 'hightrees hybrids' (my name!), crosses between D. igneum and D. pulchellum) together with an unnamed hybrid lily.

A few plants which have performed recently under glass. Lilium formosanum v pricei, grown from seed in 2013 has been rather disappointing. Several buds aborted and the foliage is in less than excellent condition. Probably it would have been happier stood outside. The flowering was very brief, but at least it looks as if it will live another day.

Lilium formosanum v pricei Lilium formosanum v pricei

Eriogonum ovalifolium v nivale like hot dry conditions and so it ideally suited to the alpine house in summer (!). It has now turned a pretty pink having opened cream.

Eriogonum ovalifolium v nivale

This is by no means the first time I have flowered Gentiana georgii, and the last plant I owned flowered for four successive summers before giving up the ghost. This is the first flowering for the present incumbent. Grown from seed, it is surprisingly forgiving of summer dry heat under glass, although I suspect it too would be happier outside in the hotter months.

Gentiana georgii

I am finishing with Crinodendron hookerianum as this is the first year it has reverted to its true character having been cut to the ground five years ago. It flowered very late this year, well into July, but has now more or less finished as I write. The giant himalayan lily with a similar name, Cardiocrinum, has also just finished.

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