28 Litres a Day Saved by a Hozelock Cloud Controller on a Greenhouse Drip Line

The bench record behind the 28-litre saving starts with an inline flow meter on the 13mm supply pipe. On a hot day in late June, the meter showed about 68 litres used by a tomato and pepper bench watered from 15 drippers running twice daily on a manual timer. Each dripper was rated at 2 litres per hour. After a Hozelock Cloud Controller took over, with a soil-moisture input linked to the schedule, the same bench recorded about 40 litres on a comparable day.

Those figures belong to one greenhouse line, with the same drippers, pipe and barbed fittings left in place. The hardware at plant level did not change. The difference came from the valve opening for shorter periods and staying shut when the compost had enough moisture for the crop.

The old manual timer had drifted upward during hot spells, because adding a few minutes felt safer than risking a dry bench. The controller trimmed the second daily run from 12 minutes to 7 minutes once the moisture reading passed the chosen cutoff. A rain-and-temperature skip also cancelled the evening run on the two overcast days in the metered week. Hand watering often misses those small omissions, because checking each pot takes longer than giving the whole bench another soak.

Scheduling the greenhouse bench

The Cloud Controller was paired with a capacitive soil-moisture probe pushed into one representative pot. The setup notes recorded a 45 percent volumetric water content cutoff for that bench. Treated as a local controller setting, it made the morning cycle run below the cutoff and allowed the evening cycle to be skipped above it.

Across the measured week, evening watering happened on three days out of seven. That change accounted for most of the fall in daily draw.

The delivery calculation explains why the totals moved so quickly. A 2 litre-per-hour dripper supplies 0.4 litres in a 12-minute run. Fifteen drippers supply 6 litres per cycle, and two cycles give 12 litres of scheduled delivery before any extra manual lengthening is added. During hot weather, the manual timer had crept toward 18-minute cycles. A shorter 7-minute evening run, combined with probe-led cancellations, moved the daily use from the high-sixties toward 40 litres.

A single probe still reads only one microclimate. The pots at the gable end dried faster than those near the door. The practical answer was to put the probe in the fastest-drying pot, letting the driest plants set the schedule. Wetter pots stayed a little damp, while the plants most likely to flag were protected.

That choice spends a few litres against an ideal pot-by-pot schedule. A hobby greenhouse line cannot usually give every pot its own threshold, valve and weather rule. The probe has to stand for the bench, so its position matters as much as the number on the controller screen.

The rain skip also needs watching in a greenhouse. Outdoor rain does not wet pots under glass. In this setup the skip was tied to weather conditions that also reduced heat and transpiration, so the cancelled evening runs matched slower drying on the bench. In a hotter house with poor shading, the same rule would need a closer look.

Taking the drip line off for winter

The 13mm line that behaved well in June becomes vulnerable in November, when standing water can freeze, split the tube wall and push barbed elbows apart at the first hard frost. The bench may even be busier then, holding tender fuchsias, pelargoniums and dahlia tubers lifted from the border.

Disconnect the line at the tap manifold and blow it through with a foot pump, or leave the end caps off so it can gravity-drain onto the greenhouse floor. The Cloud Controller valve belongs indoors after the season closes, because its solenoid and AA cells dislike sub-zero storage, and damp greenhouse air can corrode battery contacts over four unheated months.

Winter plants on the same bench

For overwintered plants, airflow matters more than heat. A minimum of 5C keeps most tender perennials ticking over. A single tubular heater on a frost-stat under the bench costs less to run than a fan heater warming the whole greenhouse volume.

Pots need gaps between them. Botrytis travels through touching foliage in still, damp air and can become the fastest winter loss on a crowded bench. Hand watering takes over once the drip line is drained, aimed at the compost and kept away from the crown. Yellowing leaves are pulled the day they show, before they collapse into a damp mat on the pot surface.

Vine weevil under irrigated pots

Warm, moist compost beneath a summer drip line suits vine weevil larvae. Adults leave scalloped notches along leaf edges, while the C-shaped white grubs do the serious damage underground by eating roots. A potted heuchera or primula can look acceptable from above until it lifts clean out of the compost with almost no live roots attached.

Nemasys Vine Weevil Killer is a suspension of Steinernema kraussei nematodes. It is watered onto compost sitting between 5C and 20C, and soil temperature is the useful reading. Below 5C the nematodes are effectively inert, so the practical treatment windows are spring and early autumn.

A drip-irrigated bench is a strong candidate for a drench because the compost already contains the moisture nematodes need for movement. Evening application with a watering can also keeps the organisms away from UV light, which kills them on contact. The watering pattern that kept the bench evenly moist in summer makes the autumn drench easier to carry through the rootball.

Box beside the greenhouse door

Clipped box in pots beside a greenhouse door catches spray drift and warm humid air. Cylindrocladium buxicola favours those conditions. The disease shows as dark leaf spots, black streaks on stems and bare patches that can appear almost overnight in a warm wet spell.

Hard cutting of affected growth, disinfected shears between plants and removal of every fallen leaf from the pot surface take away much of the inoculum. Topiary Feed and specialist blight-resistant cultivars can help. On a domestic scale, the useful controls are airflow and dry foliage: pots spaced apart, water delivered at the base and greenhouse spray drift kept away. Where box has failed repeatedly, Ilex crenata gives a similar clipped outline without hosting the same pathogen.

Keeping support wire taut

The vines and cordons fed by the drip line still need taut support wire to carry their fruit. A Gripple wire tensioner is quicker than a straining bolt. Its one-way jaw takes 2mm to 3.25mm wire, internal ceramic rollers grip the strand, and a Gripple tensioning tool pulls the line to a measured load, up to about 300kg on the standard medium unit.

Feed the wire through, hook the tool onto the tail and pump until a plucked wire gives a clear note. Retensioning is the main advantage over a turnbuckle. A quick pull with the tool takes up mid-season stretch without dismantling the line.

Hostas, slugs and damp compost

Any irrigated bed feeds slugs as reliably as it feeds hostas. The shredded leaves seen in June come from the same damp warmth that helps the plant grow.

Copper tape around pot rims, wool pellets on the soil surface and nematode drenches of Phasmarhabditis hermaphrodita all reduce damage. In a hosta collection, the most dependable move is choosing thick-leaved cultivars. Blue-leaved hostas such as Halcyon and the large Sum and Substance have a waxy cuticle that slugs work through much more slowly than thin green leaves.

A torch after dark and a bucket can remove breeding adults directly in twenty minutes. Grit and eggshell barriers underperform in trials when determined slugs meet wet weather, so hand-picking and resistant cultivars sit above those remedies in an honest ranking.

A moisture threshold in hosta pots could be tuned to leave the surface drier at dusk, when slugs are most active. The unanswered part is whether that drier evening surface would spare leaves without leaving the roots short by midday.