31) A “cabbage cage” (brassica cage) to guard cabbage plants against butterflies

In this tip:

  • Introduction
  • A)# Small cage
  • B)# Big cage

Introduction

During warm and sunny weather, cabbage white butterflies can visit your cabbage plants. Female butterflies lay their eggs underneath the leaves of the plants. After some days to weeks there are caterpillars that eat a lot of plant material. The big caterpillars often “hide” in the white cauliflower or in the broccoli. Or between the leaves of Red Cabbage, Savoy Cabbage or White cabbage.

When preparing the cabbage in the kitchen, one should take care of searching and removing all caterpillars, otherwise you’ll have an unpleasant surprise on the plate.

On the photo above you see eggs of butterflies on cabbage leaves. Each day you can inspect the bottom sides of leaves of cabbage plants for eggs or caterpillars and remove them.

It’s easier to grow the cabbage plants in a “buttefly proof” cage. In this post 2 cabbage cages are described.

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A)# Small cage

For the school garden in my village, I made this small cabbage cage. Surface area is about 100 x 130 cm (3 ft + 3,5 inch  x   4 ft + 4 inch).  Heighth is 70 cm (2 ft + 4 inch).

The side walls and the cover consist of (pieces of) iron wire netting.  At each piece, bamboo sticks are fixed with tie wraps. The side walls are connected to each other using tie wraps too.

Below there are photos and a short description.

A1) Idea:

Many years ago I made this “coop” for our guinea pig. It consists of 4 pieces of wire netting to form the sides. And it has a cover (lid) made of wire netting too. The cover prevents cats from entering. The netting wire is 1 mm thick. All sides are connected to each other using small iron split key rings. The lid is fixed to 1 side with iron split key rings.

Due to the metal rings, the coop can be folded. So easy to transport or to store.

One can make a cabbage cage of a similar construction. Below more info about it.

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A2) Parts needed

  • Bamboo sticks
  • Tie wraps.
  • Iron wire netting, mesh size is 0.5 inch (12.7 mm). The netting is 1 meter (100 cm,   39.5 inch) high and 5 meters wide.

Cabbage plants are about 60 centimeters (2 ft) high so the cage must be about 60 to 70 centimeters (2 ft   to   2 ft 4 inch) high. I use 1 meter high netting. Mesh opening of the netting must be less than 2 centimeters (0.8 inch) to keep the butterflies out. Mesh openings of 12.7 millimeters (1/2  inch) are okay. The big cabbage cage has this mesh too and no butterflies pass through it.

Iron wire netting 12.7 millimeter (0.5 inch) mesh with a wire thickness of 1 millimeter is rigid (and expensive). You can use thinner wire, for example 0.65 millimeters (1/40 inch) thick.

And use bamboo sticks and tie-wraps to make a rigid cabbage cage of this thin thready wire netting.

Use this thin wire netting (5 meters wide, 1 meter high). It costs about €18.00. I used all wire netting to make the cabbage cage “as big as possible”.

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A3) Construction

Tip: Use gloves when handling the materials.

Remove the wire. Unroll the netting wire.

This wire netting is a few inches longer than 5 meters. At this end, it has been cut right next to the metal wire.

At the other end there are short (sharp) iron wires.

At this netting, iron wires are welded and covered with zinc. On this photo you see that all wires of one direction (/) have been laid on wires of the “opposite  direction” (\). And welded at the crossovers.

Tip: Cutting the wire goes well with a nail clipper. Do not cut seperate short iron wires but cut some more material as shown on the photo above. This is to overcome single short iron wires all over the place during cutting.

Use a file to remove sharp edges after cutting. This goes well when putting the wire netting on the edge of a wooden board during filing.

Cut 5 pieces of 70 x 100 centimeters (27,5 inch x 39.5 inch) from the roll of wire netting. You see the 5 pieces at the left side of the photo. At the right side you see the piece of wire netting that is left over; 150 x 100 centimeters (5 ft  x 39.5 inch).

Attach 4 bamboo sticks at one piece of wire netting of 70 x 100 cm (27,5 inch x 39.5 inch) using tie-wraps. Step by step description;

  • Lay the piece of wire netting on a floor or pavement.
  • Use 4 (straight) bamboo sticks that are about 4 inch (10 centimeters) shorter than the wire netting.
  • Lay each stick on the wire netting at about 1 inch from the side, “right above a wire”.
  • Fix the bamboo stick (“loose”) using tie-wraps.
  • Put each tie-wrap slanting (alternating / and \ ) through 2 holes of the netting.
  • Distance between tie-wraps at 1 stick is about 12 centimeters (5 inch).
  • When all tie-wraps are fixed and the stick is correct, tighten all tie-wraps.

Repeat these steps at another piece of wire netting of 70 x 100 cm (27,5 inch x 39.5 inch). So you end up with 2 side pieces of 70 x 100 centimeters with bamboo sticks.

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Remark: instead of tie wraps you can use pieces of thin iron wire to fix the bamboo sticks to the wire netting.

My experience: Tie wraps can break sooner or easier than thin iron wire during usage. So you better use iron wire.

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The other 2 side pieces can be made bigger, about 70 x 130 centimeters. You can do that as follows;

  • Use one piece of 70 x 100 centimeters (27.5 inch x 39.5 inch).
  • Cut 2 narrow pieces, each 70 x 30 cm (27.5  x  12 inch), from this piece.
  • The residual piece, 70 x 40 centimeters (27.5 x 16 inch) will be used for the lid later.

  • Lay one narrow piece (70 x 30 cm) next to one piece of 70 x 100 cm.
  • Connect the narrow piece of 70 x 30 centimeters to the 70 x 100 cm piece using tie-wraps.
  • Between 2 tie-wraps there are 8 meshes of the netting wire.
  • When needed (e.g. opening between 2 pieces too big) put extra tie-wraps in between.
  • You end up with 1 big piece of wire netting, size 70 x 130 centimeters.
  • Use the same steps to make the 2nd piece of wire netting of 70 x 130 centimeters.

Remark: instead of tie wraps you can use pieces of thin iron wire to connect 2 pieces of wire netting.

My experience: Tie wraps can break sooner or easier than thin iron wire during usage. So you better use long iron wire and “string” it through many meshes to connect the pieces of netting.

  • Fix 4 bamboo sticks to the piece of wire netting of 70 x 130 centimeters. Use the same steps as described above (at the other piece of wire netting).
  • ((on this photo the side piece of 70 x 100 centimeters)).

Repeat these steps to make the 2nd side piece of 70 x 130 cm. So you end up with 2 side pieces of 70 x 130 centimeters with bamboo sticks.

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Now you have 4 side pieces; 2 pieces of 70 x 100 centimeters and 2 pieces of 70 x 130 centimeters.

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Attach the 4 sides to each other to make the sides of the cage. Use tie-wraps to fix together.

strip 11

stripjes vast

Or use plastic clips of this type to fix the 4 sides of the cage together.

  • Put the tie-wraps or clips through meshes (holes) in the second row from the end. (When using the first row, sides can get loose due to a bad welding at this first row).

My experience: Tie wraps can break sooner or easier than plastic clips during usage. So you better use the plastic clips. After loosing the clips, you end up in 4 seperate sides that can be transported or stored easily.

  • At each corner, use 3 tie-wraps (or more) to connect the sides.
  • This photo also shows how sides of 130 cm x 70 cm have baan made using 2 pieces of wire netting, connected with tie- wraps.

  • The cage (sides) can be folded; useful during transport or storage.

  • Use left-over wire netting (150 x 100 centimeters), the residual piece (70 x 40 centimeters), bamboo sticks and tie-wraps to make a lid. Use 2 extra bamboo sticks to minimize bending of the lid.
  • The lid fits “well over the sides” to prevent butterflies from entering. The lid is about 2 inch longer and broader than the cage.
  • The lid has 4 bended edges and 4 bended corners.

  • Close up of a corner of the lid with bended edges and bended corners.

  • The lid is about 2 inch longer and broader than the cage.
  • To make the lid broader than 1 meter, the residual piece of 70 x 40 centimeters has been used. Some extra pieces (4.5 inch wide) have been cut and fixed to the wire netting using tie-wraps.

  • You can fix one side of the lid to the cage using these strips. Remove the strips and lid before transport or storage.

  • The cage can be opened. The lid is flexible due to this construction. When desired you can use 2 laths to keep the lid open.

The small cage is used in this school garden, protecting 6 cabbage plants from butterflies.

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Remark 1: Fixing the lid.

To prevent butterflies from entering via openings underneath the lid, you can fix the lid to the side using elastic cord with hooks. Do this at all 4 corners of the cage.

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B)# Big cage

When you click on the photo above, you see it screen wide.

Dimensions: length about 260 cm (8.5 ft), width 170 cm (5.5 ft), heighth, 60 cm (2 ft).

In this cage, there is room for 5 rows of 3 cabbage plants each. When you plant 4 rows, and a few weeks later the 5th row, the plants in the last planted row can get oppressed.

You better plant all 15 cabbage plants at the same period in the cage.

Plant cabbages that are less “butterfly sensitive” outside of the cage, for example curly kale white cabbage or Brussel sprouts. As shown on the “wide” photo above.

Below a description.

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B1) Parts needed

The cabbage cage consists of these parts:

  1. At the sides there is metal wire netting. It has about 0.5 inch square mesh. Netting highth is about 63 cm (25 inch).
  2. In each corner there is a (metal) tube in the soil.  About 25 inch of each tube is above the ground. The tubes support the wire netting.
  3. A rectangular frame made of wooden laths. At each corner there is a pen. Each pen fits in a tube in the soil. This improves the robustness of the cabbage cage.
  4. Nylon or plastic cord. It has been wrapped around the laths and through the meshes of the wire netting. It makes the cage “butterfly thight”.
  5. Another rectangular frame made of wood. It acts as a lid. In the frame there is a net with small mesh so butterflies can not pass this net. The lid lays with 4 screws on the rectangular frame. The lid can be removed or it can be opened. A wooden lath supports the lid while opened.

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B2) Parts description

Here is a description of the 5 parts.  There is information about making, remodeling or adaptation of the parts.

1.   Metal wire netting

On this photo the wire netting is put on the garden soil. The netting has the same mesh opening (12.7 millimeters, 0.5 inch) as at the small cage. Height is about 60 centimeters (2 ft). When 4 tubes are in the garden soil, wire netting is mounted around them.

I’ve got this netting from a colleague allotment gardner who stopped with gardening.

2.  Tubes

These tubes are made of aluminium. They have been used at roll-up blinds. The tubes are about 1.5 inch wide and 4 feet long.

Maybe you can buy this type of tubing at a D.I.Y. shop.    P.V.C. tubing can also be used, I think.

3.  Rectangular frame

Here a photo of the rectangular frame. It has been made of wooden laths of about 2 inch wide and 1 inch thick ( 50 x 22 millimeters).

At each corner there is a plastic connecting plate and a pen.

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The connecting plates are triangle shaped pices of polypropene. They have been sawn from a plastic cutting board of about 5/16inch (8 mm) thick.

In each plate there are 4 holes. The nylon or plastic cord is put through these holes during wrapping.

After assembling, at each corner, a small piece of lath has been sawn (hacksaw). This forms some space between the laths, so rain-water can flow away.

Instead of plastic connecting plates you can use metal corner braces. On this photo the rectangular frame with metal corner braces (design 2009). Metal connecting material will rust and is not so robust as polypropene. A frame with metal corner braces is not so strong and form-retaining as with plastic plates.

Plastic plates are also useful when laying the frame on the 4 tubes in the soil. More about this at “Assembling the cage”.

For each pen you use a long wood screw, a metal nut ring and a piece of hose.

The triangles have been fixed to the laths using wood screws.

The wood screw with ring and piece of hose is screwn through a hole in the plastic plate into the wooden lath.

On this photo you see the pen fixed in the wooden lath.

Temporary remove the wood screw next to the pen at all 4 corners of the frame. This screw is not in the same lath as the pen. Now you can fold the frame. The folded frame is easy transportable. Later unfold the frame and mount all 4 screws again.

Or mark the corners and dissamble the frame in 4 seperate laths (with or without plastic triangles). Assemble the frame in the garden.

4.  Cord

Four pieces of nylon or plastic cord to fix the metal wire netting to the frame.

5.  Lid

The “lid” has been made of wooden laths of about 1 1/4 inch x 1 inch (3o x 22 millimeters). Laths are connected to each other with plastic connecting plates.

At the inner side of the frame, so at one side of each lath, there are iron nails. Distance between nails is about 3 inch. Nails will be used to fix the net later.

The nails are in the wood sloping so later the net will not slip away so easy. The nail head is nearer to the plate than the position where the nail enters the wood. All nails are sloping in the same direction.

When you remove 1 screw in each plastic connecting plate (the right screw), you can fold the lid frame. So easy transportable. Or dissemble the frame and transport 4 laths (with or without plastic triangles).

At each long lath of the lid frame, there are 2 L-shaped wood screws (at outer sides). Distance between each L-shaped screw and a corner is about 40 centimeters (1 ft   4 inch). The lid frame rests on the cage with the 4 L-shaped screws. You can open the cage (lift the lid) at each long side. You can keep the lid open by putting a vertical lath under the lid.

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In the frame of the lid there is plastic netting.

This net has small mesh size. The butterflies will not pass.

The sticker of the net.

On this photo you can see that the mesh of this net is about 1 x 1 centimeter (0.4 x 0.4 inch). Small enough to keep the butterflies out of the cage.

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B3) Assembling the cage

When folded, open the frame. Lay the frame on the garden soil. Put in the 4 screws that have been removed prior to “folded transport”. Do not tighten the screws.

Next step is adjusting the frame so making the frame at right angles again. Do this by tightening a nylon string from one corner to the opposite corner.

From one corner…..

….to the opposite corner.

Use a cord with a loop. Put the loop around the pen. Put the other side of the cord to the opposite corner, tighten and determine the distance. Put a small knot in the cord or keep it fixed between thumb and index.

Then determine in the same way the distance between the 2 other opposite corners. Most of the time this distance is some shorter or longer than the first determined distance. This means that the frame is not rectangular, so it has no 4 right angles. Then “change the form” of the frame a little and determine both distances again. Continue until both distances are (almost) equal. Then fix all screws in the 4 corner plates.

Lay the frame on the garden soil, at the place where the cage must be built.

When the frame is at the right position, push at each corner the pen into the soil. Then take away the frame. Now you have 4 small holes in the garden soil at the position of the 4 tubes.

This metal tube has a diameter that is bigger than the tubes of the cage.

Hit the big metal tube in the garden soil at each small hole. Use a wooden hammer or put a wooden lath on top of the tube and hit with a metal hammer to overcome damage of the tube. Take the tube out of the soil and tap against it to remove the soil from it. Repeat this until the hole in the soil has the same depth as the length of this big tube.

Lay the frame on the garden soil and check if all 4 pens fit into 4 holes in the garden soil. Then remove the frame again.

Put one metal tube in each hole. Hit each tube into the soil until it is about 2 feet above the soil. Use a wooden hammer. Or hit with a metal hammer while putting a wooden block on top of the tube. This is to prevent damaging the tube.

Put te frame on the metal tubes;

  • put (at 2 adjacent corners) the plastic connecting plate on the tube.
  • lift the frame at the 2 other adjacent corners and put the plastic plates on the tubes.
  • now 4 connecting plates of the frame is on 4 tubes.
  • at each corner put the pen into the tube.
  • when needed, bend a tube a little bit aside to have the pen fitting into the tube.

Keep the frame on the 4 tubes until you start digging the soil.

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Right before digging, take the frame from the 4 tubes and lay it elsewhere on the soil. The 4 tubes remain in the garden soil.

Dig the soil around and between the tubes. This works well.

After digging, lay stepping boards on the garden soil, so earth will not be treaded down.

Make a small furrow between the 4 tubes. In this furrow a small lower part of the metal wire netting will be digged in.

Put the metal wire netting around 3 tubes. On the photo the netting has been put around all tubes exept the left rear tube.

Dangle the “last tube” (rear left) in the garden soil to make a big round hole in the earth. Then take this tube out of the soil.

Put this tube at the “inner side” of the wire netting. Use this tube to push against the wire netting until the tube is above the hole in the soil. Then put this tube in the hole in the garden soil again. Tread down the garden soil next to the last placed tube.

The metal wire netting is now around all 4 tubes. Push the lower part of the wire netting into the small furrow.

Put the frame on the 4 tubes again. The pens are next to the tubes.

At each corner, put the pen into the tube.

At the corners it can happen that the frame is somewhat higher than the top of the metal wire netting. Then carefully hit the corner of the frame until the tube is at the right depth. Again use a wooden hammer or a wooden block on the frame when using a metal hammer.

Then put earth into the furrow to fix the lower part of the metal wire netting.

Wrap nylon or plastic cord through the upper meshes and around the laths. So the wire netting fits to the laths. You better use short pieces of cord, about 2 meters (6 to 6 ft). Put a knot in the end piece of a wrapped cord. Tie a new cord on the end piece of the wrapped cord, just next to the knot. Continue wrapping until you have a new end piece of wrapped cord. Tie a new cord etcetera.

Put the lid frame (without net) on the frame. When you do this without any help from another person, first put it “skew” on the frame.

Then turn the lid carefully until it is correct on the frame. The lid must lay on all (4) L-shaped wood screws (at outer sides). There are 2 L-shaped screws at each long side. Each L-shaped screw is about 16 inch (40 cm) from the corner.

When the lid is stuck (jammed), you can make the lid a little bit smaller. Take 2 adjacent screws out at one corner. Shift the connection plate on the lath and put in the screws again. Chipboard screws can be put in wood without predrilling. But you may drill or use a thinner chipboard screw. Next step is swopping the thinner screws for the original chipboard screws.

Fix 2 laths slanting on the lid frame. When the lid frame is still stuck (jammed), you can eliminate stucking by screwing the slanting laths “somewhat further”. So push against one lath of the lid and fix the slanting lath.

Take the lid frame from the cage and put it on 3 big flower pots at an empty area in the garden.

Put the net on the lid above the slanting laths. The net will not sag so far. And will not rest on the cabbage plants. So no risk of butterflies laying eggs on the plants.

Tighten the net a little. Fix the net to some nails at 2 corners of one short side (on the photo above at the right side). Lay the “rest” of the net a little over the other laths of the lid frame.

  • Fix the net behind (over) the 2 L-shaped screws at the front long lath (at the bottom of the photo).
  • Fix the net to some nails at 2 corners of the other short side (on the photo above at the left side).
  • Lay the rest of the net over the laths.

Tighten the net and fix it to all nails in 1 long lath and 2 short laths. On the photo above at the right, left and lower (front) side.

At the other long lath there is too much net material (on the photo at the top). Tighten the net a little. Again and again, at a part of the net, cut the surplus of the net and fix it over the 2 L-shaped screws and over the nails.  Cut the surplus net at the left side.

Check if the net is fixed over all nails.  When not, fix the net over the “empty” nails.

Push all loose net material in the “space” between net and top of the frame laths. So there is no net hanging or can get jammed between lid frame and cage.

Put the lid on the frame to close the cabbage cage. Lay the supporting lath on the lid when not used.

On this photo the cage has been opened at the front side. The lath supports the lid.

This “old” photo shows the v-shaped end of the supporting lath.

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6 thoughts on “31) A “cabbage cage” (brassica cage) to guard cabbage plants against butterflies”

  1. This is an amazing description. thank you very much. Quite a fantastic design and thoughtfulness to post this so carefully. Much appreciated.

    1. Hello John,
      Thanks for the complement.
      Indeed with this “cage” no caterpillars in or on the cabbages.
      It takes some time to build the cage, but once built, you can use it each season.
      Sjef

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