16) Tips about kohlrabi, cauliflower and broccoli (and other cabbages)

In this tip:

  • Introduction
  • A)# Sowing cabbage plants in the garden soil (in a small seedbed)
  • B)# Growing Cauliflower
  • C)# Growing Green Broccoli
  • D)# Growing Kohlrabi
  • E)# Other types of cabbage

Introduction:

Cabbage plants (cauliflower, broccoli, kohlrabi, curly kale, Brussels sprouts and so on) grow well outside in your garden at a temperature between 10 and 20 C (50 to 68 F). The plants like a wet, cold climate. They grow best at a windy place in the garden where they suffer least from plant diseases and insect attacks.

In a greenhouse or at a windless spot, the air is warm and moist and damp so diseases or insects or plagues easily can strike.

All types of cabbage

In this tip, growing of Cauliflower, Broccoli and Kohlrabi is described in detail. And there is a short description for growing other types of cabbage, such as Brussels Sprouts, Curly Kale, Savoy Cabbage, White Cabbage, Pointed Cabbage (Oxheart Cabbage), Palm Cabbage, Red Cabbage, Chinese Cabbage.

Cabbage plants

  • From March 1 (later winter) on, you can buy cabbage plants in a garden shop or at a plant grower. Often, these plants grow in “soil blocks” (cube-shaped root balls).
  • From early January (mid winter) on, or even earlier, you can sow cabbage plants “at home” and grow them in flower pots. This is described in  tip 19)  .
  • From January (mid winter) on, you can sow and grow cabbage plants in the garden soil. This is described below in chapter A)#. But outdoors in the cold weather seeds do not germinate so fast and the cabbage plants will grow slowly.

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A)# Sowing cabbage plants in the garden soil (in a small seedbed)

You can sow cabbage plants in the garden soil from January (mid winter) on.

It is useful to sow cabbages in a seedbed. A seedbed is lower than the surrounding soil or there’s a little dam around it. The soil does not dry out fast and when watering, the water sinks into the soil towards the roots.

Below a description;

  • Use a fork or a garden trowel to loosen the garden soil.

  • Use a rake to flatten (level) the garden soil again.

  • Put a wooden frame on the loose garden soil. More info about this frame in tip 2, nr 69.
  • (You can also make a seed bed without using the frame, see 2 photos further).

  • Use a small wooden board to shove garden earth against the outer sides of the frame.
  • Press firmly on the shoved soil. In this way you make firm dams around the seedbed.

Remark:

  • You can make a lowered seedbed without using a wooden frame; just shove garden earth from the center towards the sides (using a wooden board).

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Cauliflower, Broccoli and Kohlrabi need much nutrients (manure) when growing. Curly Kale plants and Brussels Sprouts plants need less nutrients. When you mix the soil with agricultural lime, there is less risk of the plant disease “Clubroot” (see further in this tip).

Mixing manure and lime through the garden earth goes well in this way:

  • Dig garden earth from the bottom of the seedbed and put it in a bucket.
  • Continue until the bottom of the seedbed is 5 to 10 centimeters (2 to 4 inch) deeper than the surrounding garden soil level.
  • Use a board to flatten the bottom of the seed bed.

  • Make sure you have dry fine-grained manure (blue bucket) and agricultural lime (margarine box).

  • Add manure  and agricultural lime to the garden earth in the bucket.

  • Mix manure and agricultural lime with garden earth; shake and turn the bucket.
  • Empty the contents of the bucket into the lowered seed bed.
  • Spread the mixture in the seedbed and flatten the upper side of the mixture.

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The photos below show a seedbed with a wooden frame. This description also applies to a seedbed without wooden frame.

  • Spray water on the soil in the seedbed (watering can with a fine sprinkler head).
  • Hold the sprinkler head close to the garden soil for “soft watering” to keep the garden soil “loose”.

The next photos show a place mat and sowing stick for sowing. But you can also sow freehand.

  • Wait until water has sunk into the soil.
  • Put a place mat with holes on the soil. Distance between 2 holes is 6.5 centimeters (2    9/16  inch).
  • Use 4 iron pens to fix the place mat to the soil. More info in tip 2, nr  70.

  • Use a sowing stick to make sowing holes in the soil. Info in tip 37.  

  • Make a sowing hole at each mat hole. Depth 0.5 to 1 centimeter (1/4 to 3/8 inch).

  • Drop 2 or 3 cabbage seeds at each sowing hole;
    • Use a shift fall tray (shove drop tray) of tip 33.
    • Or put seeds in a (white plastic) tray. Use tweezers to pick up the seeds and to drop them in the sowing holes.
  • After sowing, remove the place mat.

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Without a place mat, sowing stick and shove drop tray, you can sow as follows:

  • Use the point of a pencil to make sowing holes in the soil of the seed bed.
  • Put seeds in a (white plastic) tray and use tweezers to drop 2 or 3 cabbage seeds in each sowing hole.

Sowing holes in the garden soil, each hole with 3 cabbage seeds in it.

  • Strew a thin layer of moist garden soil on. You can use a plastic flower pot with holes in the bottom for strewing. Layer thickness 0.5 to 1 centimeter (1/4 to 3/8 inch).
  • Or use a tea spoon to put sieved dry garden sand in the sowing holes on the seeds. This dry sand becomes moist in a short time.

  • Carefully remove the wooden frame.

  • Lay a board (or something like that) over the seedbed. Reason:
    • The soil remains moist.
    • At heavy rain, no seeds will flush away.
  • Remove the board when first cabbage plants are visible.

  • Thin out when the cabbage plants are a few centimeters (about 1.5 inch) high;
    • At each group, remove the smallest plants until 1 plant is left.
    • Pull these plants out of the soil or use scissors to cut them above the soil.
  • After thinning, spray water on the cabbage plants.

  • Plant bed with thinned cabbage plants. At each sowing spot there is 1 (or no) cabbage plant. Distance between two plants is 6.5 centimeters ( (2  9/16  inch). This distance is required when using a “replanting tube” (tip 41).
  • Regularly water the plants in the seedbed.
  • Let the plants grow until they are big enough to replant.

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Remark:

As described above, you can easily grow cabbage plants indoors;

kplantjes

koolplantjes kuipje 1

kool in potjes inzet stripje 5

kool in potjes inzet stripje 6

kool in potjes minikasje

Sow the seeds on moist toilet paper, put the mini plants in flower pots with a mixture of compost, manure and agricultural lime. Useful; put the pots in a mini greenhouse with transparent cover. This protects the plants against slugs (snails), caterpillars (of Cabbage White butterfly) and cold nights or cold weather.

kool in potjes inzet stripje 4

Let the plants in the pots grow bigger. This procedure is described in    tip 19)   .

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Diseases and insects at cabbage plants:

After planting in the garden soil, cabbage plants are threatened by diseases and insects. Below a list of the common ones. And what to do against it.

  • Clubroot. At this serious plant disease, the root expands into a turnip and the plant languishes. This can happen when the cabbage plants grow in acetic soil.
    • Action: Before sowing and replanting, mix the soil with “agricultal lime” to make the soil less acidic.
  • Cabbage Root Fly. The flies lay their eggs at the trunk of the plants. Eggs turn into maggots. Maggots fall down, crawl into the ground and eat the roots of the cabbage plant. The plant languishes and dies.
    • Action: Make sure that the maggots can’t reach the roots. Put a “cabbage collar” around the stem on the soil. That is a (round black) plastic plate with an incision and a star shaped hole for the stem.
  • Cabbage White butterfly. The butterfly lay eggs at the lower side of the cabbage leaves.  The eggs turn into caterpillars that eat cabbage leaves, cauliflower and broccoli.
    • Action: Shield the plants using fine mesh and/or net. Plant the cabbages in a “cabbage cage” (see further).
  • Swede midge. This midge lays eggs on the growing point (heart) of the cabbage. Eggs turn into maggots that cause twisting of leaf stems and death of the growing point. Mainly at cabbage plants at sheltered, calm, windless places.
    • Action: Put the plants at a windy place or in a cabbage cage with fine mesh.
  • Lagging growth. The plant is lagging, slows down or stops growing (and/or has a loose cauliflower or broccoli). The plant grows in dry or poor garden soil (with many ants in).
    • Action: Put the plants in well manured, moist garden soil. Often pour much cold water around the stem. Don’t let the soil dry out.

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Cabbage cage (Brassica cage)

You can put cabbage plants in a butterfly free cage, like my “cabbage cage”. Below some photos and short info about my cabbage cage:

This cabbage cage (2.50 x 1.50 meters, (8 feet x 5 feet)) has side mesh (1.25 centimeters (0.5 inch)). On top is a lid with fine mesh nylon net. The lid can be lifted at 2 different sides or can be removed completely.

In    tip 31)   there is a description of the cabbage cage.

mineergaas 33

I have a wooden frame with fine nylon mesh. From March to August (spring to mid summer), it is over cabbage plants. After that over winter leek plants.

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Below is a description of each type of cabbage plant. How to put them in the soil and how to let them grow bigger. The cabbage types are:

  • Cauliflower
  • Green Broccoli
  • Kohlrabi
  • Brussels Sprouts
  • Curly Kale
  • Chinese Cabbage
  • Head Cabbage plants such as Savoy Cabbage, Pointed Cabbage (Oxheart Cabbage), Red Cabbage, White Cabbage, Green Cabbage.

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B)# Growing Cauliflower

B1) Putting cauliflower plants in the garden soil

Needed;

  • Cauliflower plants, home grown (in seed bed in garden soil), see A)#, or

koolplant perspotje

  • or purchased Cauliflower plants with roots in “soil blocks”, or

  • or Cauliflower plants, self grown in flower pots (tip 19).

  • A watering pot to be put around the plant. Pour water in the watering pot and the water sinks into the soil towards the roots.
  • Making a watering pot: Push the sharp point of scissors in the side wall of a plastic flower pot. Cut the upper part of the flower pot.

  • Dry, fine-grained manure (in the bucket),
  • Agricultural lime (in the margarine box).

koolvlieg koolkraag 10

  • Cabbage collars (e.g. cut from pond foil). See  tip 2)   no  9. 

  • A stepping board (to stand on during planting).

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B2) Putting cabbage plants in the garden soil

  • Use a fork or a garden trowel to loosen the garden soil.

koolvlieg koolkraag 4

  • Dig a planting hole in the soil. Put the earth elsewhere in the garden.
  • Put manure and agricultural lime in the hole.
  • Use a garden trowel to mix manure and agricultural lime with garden earth in the planting hole.

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Remark:

Or mix in this way;

  • Dig a planting hole in the soil. Put a part of the earth in a bucket.
  • Add manure and agricultural lime. Mix it with the garden earth in the bucket.
  • Put the mixture in the planting hole.

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Continued:

koolvlieg koolkraag 5

  • Put (push) a watering pot in the soil around the planting hole.
  • Make a small planting hole in the soil in the watering pot (using a tube).
  • The root ball of the cabbage plant must fit in this small planting hole.

koolvlieg koolkraag 6

  • Strew extra agricultural lime in (and at the edge of) the small planting hole.
  • Put the cabbage plant deep in the small planting hole; the lower petioles (leaves) are just above the top edge of the small planting hole.

koolvlieg koolkraag 7

  • In the watering pot, shove garden earth against the root ball of the plant.
  • Add water in the watering pot.

koolvlieg koolkraag 8

  • Let the water sink into the soil.
  • Check if the plant is deep in the soil; the lower petioles are just above the soil.
  • If higher, put extra garden earth in the watering pot. And strew agricultural lime on the soil.

koolvlieg koolkraag 9

  • Add water in the watering pot again.
  • Let the water sink into the soil.
  • Mostly the plant is deep enough in the soil; the lower petioles are less than 1 centimeters (0.4 inch) above the soil.
  • When too much earth in the watering pot, only little water fits in it. You can pull the watering pot a few centimeters (1 inch) up, then.

koolvlieg koolkraag 10

koolvlieg koolkraag 11

  • Put one cabbage collar around the plant on the soil in the watering pot. With the incision towards one side (left side photo: down).
  • Put another cabbage collar on the first cabbage collar around the plant. With the incision towards the opposite side (right side photo: up).

Let the cabbage plants grow big in the garden soil.

koolkraag 21

Cabbage collars after harvesting the cabbage plants. To be brushed and cleaned in water. Then put on a pile. After a few weeks, check if incisions and star shaped holes are good.

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Remark 1: using a plant hole tube

  • You can use a piece of thin wall pipe (6 centimeters, 2 ft diameter).

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Remark 2: putting wind shielding around the plants

  • At a big plastic flower pot, cut the bottom and a piece of side wall. You end up with a high side wall. You can use it as a “wind shielding”.
  • Put the shielding around (or in) a watering pot. Shove garden earth against to overcome blowing over. This protects the plant against heavy wind.

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Remark 3: protecting the cauliflower against daylight

To keep a cauliflower white, you have to protect it against light. Like this:

bloemkool 18

Put a watering pot (bottomless lowered plastic flower pot) around;

  • Put the watering pot around your arm,
  • Grab together a number of (inner) cabbage leaves,
  • Shove the watering pot around the caught leaves.

These leaves protect against day light; the cauliflower keeps white. When the cauliflower is bigger, put a bigger watering pot over.

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B3) Harvest

Planting in March (early spring) can result in a big cauliflower in July (mid summer). After harvesting the cauliflower, remove the (whole) plant from the garden soil. Put the leaves and the upper part of the stem on your own compost heap (or give to chickens or rabbits).

Put the lower part of the stem and the roots at the municipal waste container.

(although I put healthy cabbage roots and stems on my compost container for some years).

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B4) Remarks

B4a) Planting date

Cauliflowers planted in the garden from mid March to end of April (early to mid spring) give a harvest in June – July (early to mid summer). When planted later, the plants suffer from more plant diseases and/or insects.

B4b) Only one crop at one place

Never plant cabbage plants twice (or 2 years) at the same place in the garden. When you do so, there is more risk of Clubroot and other plant diseases.

B4c) Planting later

You can buy small cauliflower plants in a garden shop until early June (mid to late spring). You can store these last purchased plants to replant later. Like this;

  • Put each cauliflower plant with its root ball in a small bowl.
  • Put the whole outdoors on a shady spot.
  • Don’t let the root ball dry out; water when needed.

The cabbage plant stays alive, but will not grow much. You can store the plant a few weeks.

July (early summer): A cauliflower plant stored for 4 weeks after purchase. The root ball looks normal. The plant is still small.

July: Put the plant in manured garden soil mixed with agricultural lime. Put a watering pot in the soil. And put cabbage collars around the stem (the photo shows an old type of collar, a new model is also possible).

Frequently pour much cold water in the watering pot.

September (early autumn): Bigger grown plant covered with leaves against incoming light. With some holes in the leaves (made by caterpillars of Cabbage White butterfly).

End of September (early autumn): Harvested cauliflower on a paving stone of 30 centimeters (12 inch) square.

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C)# Growing Green Broccoli

When sowing, growing and replanting Broccoli, use the same information as described above at Cauliflower.

After the first harvest, you can grow small Green Broccoli in each leaf axil. And harvest them later.

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D)# Growing Kohlrabi

When sowing and growing small Kohlrabi plants, use the same info as described at Cauliflower. Below some extra info about growing Kohlrabi.

Kohlrabi (temporary) growing in in too dry soil, gets fibrous, hard and not tasteful. When you water the plants often with much water, you get soft, tasty kohlrabi tubers. Big watering pots around the plants are useful.

Push a big watering pot in the soil. Mix the soil in the watering pot with manure and agricultural lime and sow or replant Kohlrabi in. See below:

koolrabi 16

  • Choose a spot in the garden. Loosen the soil (with a garden trowel). 

koolrabi 17

  • Push a watering pot (lowered bottomless plastic flower pot) in the soil.

koolrabi 18

  • Scoop some garden earth out of the watering pot.

koolrabi 19

koolrabi 20

  • Put dry (fine grained) manure and agricultural lime in the watering pot.
  • Mix manure and lime through the soil.

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D1) Sowing in the watering pot:

  • Pour cold water in the watering pot. Let the water sink into the soil.
  • Sow groups of 3 Kohlrabi seeds together in the watering pot. Distance between the groups is 10 to 15 centimeters (4 to 6 inch).
  • Strew sieved dry garden sand or moist garden earth on each group of seeds.

  • Lay a wooden or plastic plate on the watering pot against drying out or heavy rain.
  • Remove the plate when plants are visible.
  • Thin out the Kohlrabi plants until 1 plant per group.
  • Let the kohlrabi plants grow bigger in the watering pot.

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D2) Putting mini plants in the watering pot:

You can sow Kohlrabi seeds indoors on moist paper and replant mini plants in the soil in the watering pot;

koolplantjes kuipje 1

  • Sow Kohlrabi seeds indoors in a tray on (2 layers of) moist toilet paper.
  • Put a fitting lid on the tray. Put the whole indoors at 15 to 20 C (59 to 68 F)
  • Remove the lid when the biggest plants are about 1 centimeter (0.5 inch) high.
  • (Put a transparent box over the tray).
  • Make sure that the toilet paper does not dry out; add water when needed.
  • Let the Kohlrabi plants grow bigger on the moist toilet paper.
  • When the mini plants are about 2 to 4 centimeters (1 to 1.5 inch) high, they can be planted in the watering pot.

Putting mini plants in the garden soil:

  • Spray extra water on the toilet paper; this eases picking of the mini plants.
  • Pick the mini plants from the toilet paper and replant them in the watering pot.
  • Distance between the replanted plants is 10 to 15 centimeters (4 to 6 inch).
  • Each time you can put 2 mini Kohlrabi plants together in a group and thin out later.
  • Spray water on the soil in the watering pot.

  • Put a board or plate (and a brick) on the watering pot, against drying out and heavy rain or wind.
  • Remove the brick and plate when plants are bigger.
  • Water the plants in the watering pot frequently with much cold water.
  • Let the Kohlrabi plants grow big in the watering pot.

When using this procedure there are small Kohlrabi plants growing in the garden soil 1 to 2 weeks after sowing. And no thinning needed (except when you planted 2 Kohlrabis in a group).

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D3) Putting small plants in the watering pot:

You can easily grow Kohlrabi plants in flower pots, (see tip 19).

koolplantjes kuipje 1

kool in potjes inzet stripje 5

  • Sow Kohlrabi seeds indoors in a tray on (2 layers of) moist toilet paper.
  • Put the mini plants in flower pots with a compost/manure/agricultural lime mixture.
  • Let the plants in the flower pots grow bigger.

  • Big Kohlrabi plants, big enough to replant.

koolrabi 21

  • Make round planting holes in the soil in the watering pot.

koolrabi 29

koolrabi 22

  • You can use a plastic tube to make the planting holes.
  • Make the holes big enough; the flower pots must fit in.

koolrabi 24

  • Make enough planting holes.

koolrabi 23

  • Put flower pots with Kohlrabi plants in the planting holes (to “fit”).
  • Remove the flower pots again.

koolrabi 25

  • Take each Kohlrabi plant with root ball out of the flower pot.

koolrabi 26

koolrabi 27

  • Put all plants with root balls in the planting holes in the watering pot.

koolrabi 28

  • Pour cold water in the watering pot; garden earth flows around the root balls. So the kohlrabi plants gets rigid, tight in the garden soil.

koolrabi 14

  • (Other) large grown Kohlrabi plants in a watering pot.

koolrabi 15

  • Big Kohlrabi plants in a big watering pot, big enough to harvest.

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General info about Kohlrabi:

  • You can put a layer of manure on the soil in the watering pot against drying out. When watering, nutrients flow towards the roots of the plants.
  • Let the Kohlrabi plant grow big in the watering pot.
  • Regularly (often) pour much water in the watering pot to get soft, delicious kohlrabi tubers.
  • My experience; Kohlrabi plants are (almost) never attacked by the maggots of the cabbage fly; no “cabbage collars” needed.
  • When there are caterpillars (White Cabbage Butterfly), take (grab) them of the leaves. Or hit against the leaves so the caterpillars fall on the garden soil.

gaas kapje 10

  • You can put a wire mesh protector over to keep the butterflies away (tip 2, no 80).
  • Some Kohlrabi tubers can burst due to too little water supply or a growth stop after replanting.

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E)# Other types of cabbage

Brussels Sprouts

Useful: Sow on moist toilet paper, put the mini cabbage plants in flower pots with a compost/agricultural lime mixture. Let the plants grow bigger. Put a tray with flower pots outdoors by day and indoors by night (against snail-eating).

Let the plants grow bigger until they can be replanted in the garden soil

You can replant the Brussels sprouts plants in the garden soil as follows;

    • Use a thin wall tube (10 centimeters (4 inch) diameter) to make a big planting hole in the soil, 5 to 10 centimeters (2 to 4 inch) deep. Wiggle the tube to make the planting hole bigger and \  / shaped.
    • Use a garden trowel or a small tube (6 centimeters, 2.4 inch diameter) to make a small planting hole in the bottom of the big planting hole.

  • Strew agricultural lime in the planting hole (manure not needed at this variety).
  • Take the plant with root ball out of the flower pot.
  • Put the plant (the root ball) in the small planting hole.
  • In this way the plant is deep in the planting hole.

  • Pour water in the planting hole after planting.

  • Put many (all) Brussels sprouts plant in big planting holes in the soil.
  • Regularly (often) pour cold water in the planting holes. The planting holes serve as watering holes.
  • It takes a long time before the planting holes are full of flushed earth.

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Curly kale

Use the same procedure as described at Brussels sprouts plants.

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Chinese cabbage

Use the same procedure as described at Brussels sprouts plants.

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Head cabbage plants (Savoy cabbage, Oxheart cabbage (Pointed Cabbage), Red cabbage, White cabbage, Green cabbage)

Useful: Sow on moist toilet paper. Put the mini plants in flower pots with a mixture of compost, manure, agricultural lime mixture. Let the plants grow bigger. Put a tray with flower pots outdoors by day, indoors by night (against snail-eating).

When plants are big enough, replant them in the garden soil (with manure and agricultural lime) as described at Cauliflower. Head cabbage plants suffer less from the Cabbage White butterfly.

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