Net 24 Cabbage Hispi Plants Against Pigeons with an Enviromesh Tunnel Over 6 Metres

A six-metre run before the pigeons find it

Hispi is a pointed summer cabbage, usually ready 60 to 70 days after transplanting, and it tolerates closer planting than a drumhead cabbage. Set the plants 45cm apart, with two staggered rows 30cm apart, and 24 plants will take a bed about 6 metres long and 60cm wide.

Buy the Enviromesh for the finished tunnel, since the plant count does not tell you how much fabric is needed. For a 6-metre bed, cut roughly 8 metres of mesh. That extra length gives enough slack to pass over the hoops and leaves about 30cm of skirt to tuck or weight down along each side.

Standard Enviromesh has a 1.35mm x 1.35mm aperture. It excludes wood pigeons, prevents cabbage white butterflies from reaching the leaves to lay eggs, and blocks mealy cabbage aphid. It still passes around 90 percent of the light and allows most rain to reach the soil. Ultra-fine 0.8mm mesh adds protection against carrot root fly and flea beetle, though the smaller aperture cuts airflow. On Hispi, the standard grade is the sensible choice, since pigeons and caterpillars are what actually shred a brassica.

Hoops, height, and the edge that fails first

Half-inch alkathene water pipe makes a cheap hoop frame. Bend the pipe over the bed, push each end 20cm into the soil, and place the hoops every 75cm along the run. A 6-metre tunnel takes nine hoops.

The top of the tunnel usually causes fewer problems than the bottom edge. Pigeons seldom land on mesh that is tight, yet they will walk along the side of a bed and work at any place where the cover lifts from the soil. Trace most failed brassica coverings back and you land on that detail.

Bury the skirt in a shallow trench if the bed edge allows it. Where digging in is awkward, use a continuous line of bricks laid end to end. A small gap is enough: a pigeon can push its head under an opening of even 10cm and pull leaf through the aperture.

Cabbage white butterflies exploit the same weak point. A female on the outside of tight mesh cannot reach the crop, while one that gets under a raised edge can lay 40 to 100 eggs on the undersides of the outer leaves. The eggs hatch into green caterpillars, and those can skeletonise a cabbage in a week. Sealing the perimeter handles both threats in one job. Bird netting stops the pigeons, but butterflies pass straight through it.

After heavy rain, walk the line and look for sagging. Wet mesh can slump onto the growing point, and any leaf pressed against the cover is within reach of a pigeon beak. Tighten the tunnel by pulling the skirt back under the bricks or firming the buried edge, and leave the hoop spacing alone.

Water without opening the tunnel

Standard Enviromesh lets showers through, so the cover does not have to come off for light rain. In a dry spell, the crop still transpires hard under the 90 percent light level, and a 6-metre row of cabbage under mesh can dry faster than open ground because the reduced airflow does nothing to slow the plants making growth.

A leaky-pipe soaker set along the base of the plants, under the cover, avoids repeated lifting for watering. Connect it to a Hozelock sensor timer and set it to run at first light for 20 to 30 minutes every second day during settled dry weather. The sensor versions pause the cycle when the soil probe reads wet, which is useful under mesh because evaporation is slower and excess water can rot the stem base. Take the supply line out beneath the buried skirt at one end, so the tunnel remains sealed.

The module stage happens before any of this. John Innes No. 2 suits Hispi seedlings before planting out, as its loam base holds nutrients longer than a peat-free multipurpose compost when the plants sit in cells for three to four weeks. John Innes No. 3 is too rich for the job; the higher feed rate encourages soft growth, and pigeons find that growth first.

The neighbours

A mesh tunnel earns its keep on low crops that do not need insect pollination. Hispi fits that; a bed of broad beans next to it does not, and that contrast decides how you handle the adjoining ground.

Broad beans reach 1 metre, so the same low cover will not fit them, and the flowers need pollinator access anyway. Blackfly, the broad bean aphid, starts on the soft growing tips from late spring. Once the lowest trusses have set pods, pinch out the top 8cm of each stem. That removes the tender tissue the aphids prefer and pushes more of the plant’s energy into the pods below. If colonies are already established, a hard jet of water knocks them off, and ladybird larvae usually clear what remains within a fortnight when no broad-spectrum spray has been used.

When onions from sets share the same watering supply from a nearby raised bed, that shared line matters more than it looks. The faster drainage of a raised bed suits onions on heavier ground, because standing water around the base plate encourages white rot and later neck rot in storage. Push each set in so the tip just shows. When the tops begin to yellow and fall, usually in mid to late summer, stop watering. Lift the bulbs and dry them under cover for two weeks before storing. The concern that ties the onion bed and the cabbage tunnel together is the same one: trapped, damp air and standing water at the stem base, which is why watering control counts as much as the mesh edge does.

Cutting the crop

Hispi hearts up quickly once growth is steady. When a head is firm and at the size wanted, lift the tunnel enough to cut cleanly at the base, then put the cover back if other plants in the row still need protection.

When the whole row comes off, the mesh will have done its job on pigeons and butterflies, but the still air beneath it leaves a question worth checking on the cleared bed: those stem bases have sat in a damper pocket than the open ground all season, and whatever is left behind on them is what the next crop inherits.