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A Northumberland Alpine Gardener's Diary

This entry: 16 March 2014 by John Richards

Northumberland Diary. Entry 265.

Alpine house watering

Depending on the weather and season, the middle of March is usually when I reconnect the watering system in the alpine houses (having disconnected it in late October, to protect it from frost). I find this watering system essential to my way of doing things, so I thought I would write a little about it this week.

I suspect that the vast majority of really dedicated alpine exhibitors rarely leave home for any length of time. It is probably true that in order to produce Show plants of the very high quality that we have seen at Loughborough and Kendal over the last two weeks, growers need to spend a good deal of the summer watering plants under glass, giving each subject individual attention. Of course, this is less true of bulbs, many of which can be allowed to dry out in the summer, while many plants are much happier if they spend the summer out of doors in a cool airy plunge, where they will need much less management. Nevertheless, when it comes to most of the magnificent plants which dominate the early Shows, dionysias, Primula allionii cultivars and hybrids, they need to spend their lives under glass, receiving skilled, time-consuming management. If plunged, they need watering less often, but they still need a good deal of care.

Summer is an important time for me, when I like to get into the mountains, and undertake a lot of field work in this country too. The last thing I want to do is to spend all day carrying a watering can. Most summers I am away for two or more weeks at a time, often several times a year. I am only able to do this because of an automatic watering system in both alpine houses. In one of the houses, this has now been in place for 24 years, and is still  functioning well. I have my friend Alan Furness to thank for introducing me to a Gardena system first, although I believe he no longer uses his.

One of the first things we did when we arrived at High Trees 25 years ago was to install an outside tap, leading it through from the kitchen to an outside wall. In the summer this now carries two hose-points. One connects to a hose which is used for general watering, but the other to a permanent hose which is buried (now deep under shrubs and trees) for 25 m to the nearest alpine house. Here, first, is the tap with hoses in place.

The next picture shows where the permanent hose emerges from beneath a paver to be passed through a missing glass pane into the alpine house. Originally this was fed through a hole in the concrete base, but successive problems with hose connections (the system is under considerable pressure, and old connections tend to leak) resulted in the hose end being cut back so much that it became too short and a new shorter route into the greenhouse had to be found.

The hose is connected to what Gardena grandly calls a computer, which which is really just a clock which controls the watering cycle. A simple system controls the time of watering, the number of cycles per day, and the length of each cycle. It is possible to override this, to give a 30 minute session if plants look too dry. It is this clock which is stored indoors with the batteries removed during the winter.


A wide-bore plastic pipe is connected to the other end of the computer and runs the full length of the alpine house, out the far end, and connects to the second alpine house. At four points narrow-bore pipes are connected which feed respectively each side of the wider plunge, first house, the narrower plunge, first house, and one of the two plunges, second house (the fourth plunge is reserved for bulbs and does not have automated watering). From each of the long narrow pipes, a large number (about 30 each side) of short side pipes of varying lengths carry drip points. The first photo shows where one of the narrow pipes joins the wide-bore pipe, and the second shows a drip point.

As can be seen, some of the drip points water the plunge (most plants are in crock pots and so are largely watered through the wall of the pot), and others, in large pots, or plants which are judged to need more water, have a drip point actually inside the pot rim. Also, one part of the plunge has plants planted out into the plunge, and in artificial tufa, and some of the drip points water the tufa itself. The next photo shows the system in the second house which has had to use a Hoselock system as our local Garden Centre stopped stocking Gardena.


There are some snags with the system. The first is that it is now much harder to obtain most Gardena products, except through the internet. Also, they changed their formulations which are not always easily compatible with my original system. Hose connection points and drip points do tend to wear out, and I am now on my third 'computer' in 25 years, and they are not cheap. The batteries last a year, and they also are not cheap. In general though, the system does work well, and there have been innumerable occasions when I have been away for the best part of three weeks in summer and have returned to find my plants in good health.

I thought I would also show the rather posh thermometer that I was given one Christmas. This gives maxima and minima both inside and outside, and also humidity readings, which I find very useful. It also tells me the time and date, which in the alpine house is probably rather less valuable!


How is the time of many catkins. Catkin-bearing shrubs can add a great deal to the spring garden. I am particularly fond of corylopsis which are just reaching their best. At this time of year, any flowering shrub which is impervious to frost is invaluable (in fact we have been very lucky this spring, and the Rhododendron barbatum featured last week is still very lovely).

Here, first is Corylopsis pauciflora, a haze of small primrose bells..


If anything I am even more fond of the slightly less advanced C. spicata, which has a sturdier habit. It grows right outside the ktichen wndow.

Don't you just love the red-tipped stamens?

Most sensational of all however is Salix hookeri, seen out of the bedroom window. This is exceptionally vigorous and a big tree, so that we have to pollard it every few years. But at this time of year the 'palm' is stunning; it has the biggest male catkins of any willow I know.

The pieris, too, are approaching full flower now, and they too have avoided frost so far. As yet, none of the tender scarlet growth has appeared. First. P. forrestii 'Firecrest, now a very large plant indeed after we brought a cutting from our last garden 25 years ago..

Although it has immeasurably the better young growth, P. forrestii is less impressive in flower than its neighbour, a form of P. floribunda.

Other Ericaceae are starting to flower too, notably that lovely, reliable hybrid of the rather tender Rh. leucaspis, Rh. Snow Lady'.

Erica carnea is at its best. This is a plant we have never bought. We inherited it, and I tried to eliminate it, but it knew better, and I now tolerate it, covering a bank with a purple rug.

I showcased several porophyllum saxifrages last week, but the star at present is a form of S. marginata 'Rocheliana' that was propagated from Randle Cooke's house 'Kilbryde' 40 years ago. This is a vigorous mat-forming clone of great longevity which is one of the most reliable 'Kabschia' species I know. I think it may be a form from the south of Italy?

Finally, David Haselgrove gave me a plant of Primula palinuri, another southern Italian, when he leant that I had lost it. From past experience, this southerner is surprisingly tough and does quite well outside, but until I have propagated it, it stays in a shady place in the alpine house.

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