Hornbeam Hedge Planting

For the ‘farm’ hedges around the boundary of the site, I’m happiest with Hawthorn – which is what the boundary hedges were originally and still mostly are now, just with a few (big) gaps. Some of the Hawthorn has given way to Blackthorn, which isn’t quite as good but provides an interesting contrast. (The main problem with Blackthorn is that it spreads by suckering and the whole hedge tends to grow wider over the years. It also responds less well to hedge-laying than Hawthorn.)

For other hedges within the site, especially near the buildings, I generally prefer Hornbeam. While it’s a UK native and happy to tolerate wet ground (much better than Beech which looks very similar) it can be kept trimmed into a tidy, formal shape.

The only sensible way to plant a hedge more than a few metres long is using bare-root plants but those really need to go into the ground while they’re still dormant – which ideally means before the end of March (and even then the plants will need to have been kept in cold storage). The existing Hornbeam hedge to the South of the House lost the leaves it had kept over winter and started to bud around mid-March, indicating that new bare-root hedging would likely also be coming out of dormancy at a similar time.

Ever since the Outbuildings got completed, with the ground around them looking rather flat and bare, the plan has been to plant a hedge along the back of the parking area to the North of the Garages, to act as a wind-break and to help separate that area from the planting beds further North. That was waiting on the fence along the Eastern boundary being installed, which happened at the start of March.

What should have been a fairly quick job of preparing the ground turned into a much bigger task when it became clear the ground had been heavily compacted by all the building plant traffic. When it gets compacted, the ground here turns into a solid layer which is almost waterproof – resulting in a thin layer of mud on top of an impermeable layer below. That’s no good for planting into so the compacted layer needed breaking up (generally with a pickaxe) and forking over. To make matters worse, under the compacted layer there was a lot of demolition rubble from the old barn buildings (which had been there since the House was built) – many barrow loads of full-sized bricks and half-sized concrete blocks – so that had to come out to check the ground wasn’t compacted below it. In some places that meant digging down nearly a full metre, to expose the original topsoil.

With the made-up ground consisting mostly of subsoil, rather than topsoil, it needed plenty of organic matter adding – of which there is a plentiful supply from several years of composting the hay cut every August from the wildflower meadow. The main problem with that is judging how far all of the disturbed ground and compost will settle, so that the hedge ends up level with the adjacent parking area. Ideally I’d leave it to settle for a month or so but then that would really be too late to be planting bare-root hedging.

Previously I’ve bought bare-rooted Hawthorn and Hornbeam from a local supplier but they were out of stock of Hornbeam for this season so I used mail-order supplier Best 4 Hedging based in Chorley, Lancashire, who were also a bit cheaper. I’d hoped that by placing an order on a Monday I’d avoid the risk of the plants being stuck in-transit over a (potentially warm) weekend but they ended up shipping on the Friday and I wasn’t expecting them until the Monday but I was pleasantly surprised by DPD delivering on the Saturday.

The plants were just starting to sprout leaves – which helped to confirm none of them were dead. They were very similar to what I’d planted before, with the expected variation in heights and stem thicknesses; quite possibly they had come from the same nursery as before. I kept them in buckets of water in the dark for a couple of days while finishing the preparation work and then planted them over a couple more days. The hedge is 24m long and I’d planned on 5 plants per metre (40cm spacing in two staggered rows 40cm apart) for 120 in total. It always feels like vandalism to cut off the top 1/3 of each one after planting, but this is important:

  • To encourage more shoots to sprout from the base, for leaf cover closer to the ground
  • To reduce the number of leaves needing water from the root system while that recovers from the shock of being transplanted
  • To reduce the effect of wind loading while the plants get settled – especially since I don’t bother staking them

It’s quite hard to get a good photo of a line of brown sticks against a brown background; I’ll take further photos once they get some decent leaf-cover.

120 bare-root Hornbeam plants forming a hedge by the Garages, with a mulch layer to help retain moisture

With the rainwater harvesting system feeding two outside taps by the garages it proved easy to water in the new plants using a hose and spray nozzle. While the cost of 1,000 litres of metered mains water is only about £2.50 it’s good not to have to give any thought to the water usage. I was also careful to thoroughly soak the compost mulch covering several times, in the hope that by being wet that would be less likely to blow away in the 40mph winds forecast for a few days after planting.

Multi-Target KNX Home Automation Configurations

Generally speaking I get on very well with the KNX Home Automation standard and the ETS software used to configure a KNX installation, but every now and again it catches me out.

A recent situation was for the automated garage doors. Those are Hormann RollMatic 2 roller shutters and each one has a Hormann KNX Gateway attached to its HCP Bus. While these don’t provide a huge range of functionality, they do make it possible to open and close the roller shutters from the KNX Bus (e.g. using Home Assistant) and to trigger other actions when the shutters open and close.

The behaviour I wanted is that whenever one of the doors starts opening, it:

  • Switches on the two Indoor garage lights either side of that specific door
    • There are no windows in the garage and the garage doors are North-facing so it’s generally always desirable for the indoor lights to come on – though I’ll review that again in the Summer
  • Switches on the two Outdoor garage lights either side of that door
    • But only if it’s dark outside
  • Switches on a relay to tell the alarm system that a door is being opened

The Hormann KNX Gateway provides both a “Door open status” and a “Door closed status” output. At first glance “Door open status” looks like it will provide the necessary trigger but in fact that only changes state when the door is fully open – i.e. at the end of the motor travel. Fortunately there are configuration options to flip the “Object polarity” for both these outputs, and by selecting “Door closed status” to be “0 = Closed” (as shown below) that effectively becomes a ‘Not-Closed’ output, which changes to 1 as soon as the door starts opening.

Part of the KNX ETS Configuration screen for the Hormann KNX Gateway, showing the two “Object polarity” options

The Hormann KNX Gateways were a relatively late addition to the installation, due to availability issues, so I’d previously configured separate KNX Group Addresses for each of the Lights to enable manual control using the Home Assistant app.

The mistake I made was to link the Hormann KNX Gateway’s “Door Not Closed” output to the multiple Group Addresses I’d already configured – and the problem is that only one Group Address can be configured as the “Sending” destination for an output object. Initial testing showed that my multiple-GA configuration sort-of worked – e.g. the indoor lights initially came on when a door opened – but once the other targets were configured the indoor lights stopped working.

The fix was to link all of the lighting relay channel switches directly to the same Group Address as the “Door Not Closed” output, so the latter is only “Sending” to that one GA. There are still dedicated Group Addresses for the lights, for use with Home Assistant, but those are no longer targets for the “Door Not Closed” output.

To complete the picture, the “But only if it’s dark outside” logic is addressed using a Group Address which tracks whether it is “Daylight” or not, and configuring that as a “Lock” for the relay channels connected to the Outdoor lights. When the Daylight GA is ‘On’ the Lock is active and the status change from the “Door Not Closed” output gets ignored for the Outdoor lights. The setting and resetting of the Daylight GA is performed using the existing Home Assistant Automation rules which run at Sunrise and Sunset (although using a KNX ‘Twilight’ sensor would be an alternative and more natively-KNX way of achieving that).

The only remaining minor issue is that some of the Indoor lights switch off when one of the garage doors gets to be fully closed – which is annoying when planning to continue working inside the garage with all the doors closed. That means using the light switch (or Home Assistant) to turn them all on again. In principle, it would be possible to use the motion sensors which are part of the alarm system to control (some of) the lights, but that integration isn’t currently in place.