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How To Grow Broccoli (Sprouting)

Sowing Time
Planting Time
Harvesting Time
How To Grow Broccoli (Sprouting)

how to grow purple sprouting broccoliHow To Grow Sprouting Broccoli. In Italian the word broccoli means 'little sprouts'. It is part of the Brassica family of vegetables which also includes cauliflower, cabbages, Brussels sprouts, turnips and many of the Asian greens. The words broccoli and calabrese are different varieties of the same vegetable. In general terms, Calabrese produces green heads whereas broccoli produces purple or white heads. The most common in the UK and Ireland is 'calabrese' which confusingly, is sold in some of the super markets as 'broccoli'. For more information there is a short video on growing broccoli at the bottom of this page.

Sowing Sprouting Broccoli

You can sow purple spouting broccoli directly outside but I highly recommend sowing in modular trays, it's much easier and you are far more likely to achieve a win.
The advantages are:

1. Excellent crop establishment

2. Uniform plant development

3. Quick transplanting with minimum root disturbance

4. Gives the plant a head start against weather and garden pests and diseases

Sowing broccoli seeds in modular traysSowing in Modular trays.
Use a seed compost which has a finer texture and lower nutrients than your standard multipurpose compost. We use a seed module tray with each section being approx 2 inches deep. Here's what you do:

Fill the seed tray with compost and brush off any excess. When filling the tray rub the compost through your hands to break up any lumps. Give the tray a sharp bang on your table to settle compost.

With your fingers make small depressions in each cell about a fingernail or 1.5cm deep. Sow 1 or 2 seeds per module. If 2 seeds germinate you will have to remove the weaker seedling. Cover the seeds with another layer of compost then scrape across the top of the tray with a stick to remove excess.

Gently water your seeds. A good tip is to use a plastic bottle with small holes punched in the cap. This is less likely to wash the seed around than the heavy spray from a watering can. Place your trays in your greenhouse, polytunnel, cold frame or windowsill to germinate. They should be ready to plant out in about 4 weeks.

Seedling Care

a leggy broccoli plant grown with too little lightWhen growing seedlings indoors you be careful they don't get leggy, i.e. long spindly plants.

Seedlings become 'leggy' when they get too much heat and not enough light. If you are starting them off on a windowsill make sure they get as much daylight as possible. You can make a makeshift light box by placing a sheet of reflective tinfoil on the room side of the seedling tray. This will reflect daylight onto the darker side of the plant.

If the plants are on a heat bench or in a propagator and they are looking spindly, turn the heat down and try to give them as much light as possible.

If 2 broccoli seedlings have germinated in any of your modules you need to remove the weaker one. Don't pull the seedling out as you'll damage the roots of the one you want to keep. Nip the unlucky one with your finger nail or cut with a scissors.

watering vegetable seedlingsWatering.
It's important to keep you seedlings properly watered before you plant them out in the garden. You are actually far better to under rather than over water your plants. This may sound odd but making the roots search for water helps to develop a better root system. It's a bit like keeping fit.

You do need to be careful, however, not to let the compost plug completely dry out or it will form a crust on top and won't absorb the moisture the next time you water.
It will all depend on the weather of course but on a hot day you will need to water twice a day, if it's it's dull every 2 days will be fine.

Hardening Off

Plants that have been raised indoors will need to get used to the outdoor temperature and conditions before they can be planted outside, this will take about a week to 10 days depending on the weather.

Cold frame or cloche for hardening off vegetable seedlingsThe best way is to use a cloche or mini greenhouse. You can leave the cloche off the plants on dry frost free days and replace at night. Gradually increase the time with the cloche removed until the end of the week when you leave it off day and night.

If the weather is mild you may not need the cloche, just move the plants outside for longer periods each day. If you have started your seeds on a window sill you will need to leave them in an unheated room for a day or two before moving outside to the cloche.

Planting Out

Planting out a broccoli seedlingBroccoli is a much larger plant than you'd think so giving it plenty of space is important, 75cm around each plant is essential.

To plant your seedling make a hole in the soil the approximate size of the seedling 'plug'. You need to push the soil in around the roots firmly with your fingers to get good contact with the soil. Don't firm down on the top of the soil as this can compact it and prevent moisture getting down to the plants roots.

Water the plants after planting but do not soak them. You are better to transplant on a dull day or in the evening to prevent the plants wilting on a hot, dry day.

Pest and Disease Control.
I don't want to put you off but there are a couple of things you'll need to look out for when you've planted your seedlings. Broccoli belongs to the cabbage or Brassica family so all the same pests and diseases apply as cabbage. You can click on the link below for information on the following pests: Cabbage root fly, Cabbage White Caterpillars, Cabbage Whitefly, Clubroot.

Cabbage white butterfly eggs and caterpillarsPest Control

This is just a quick reminder to keep an eye out for the cabbage white butterfly eggs on your purple sprouting broccoli plants. Look under the leaves for the little yellow eggs and brush them off.

Also if the weather is dry be aware that broccoli needs plenty of water at all stages in its growth. Dry plants will lead to poor growth and premature budding resulting in small heads.

Crop Care

Don't forget if the summer is dry to water your broccoli. You can add a mulch of compost or bark around the plants to help conserve moisture.

If your plants need a boost you can apply some seaweed/chicken manure pellets spread widely around the base of the plant.

Staking broccoli plants supportStaking plants

With winter approaching it's a good idea to prepare your broccoli for the coming bad weather, especially if you live in an exposed site. Draw soil up around the stems of the plants to help prevent them rocking in the wind. If you live in a very windy area you can also stake the plants to be on the safe side. Drive a wooden stake in beside the plant and tie with some suitable soft twine. If the stems do become loose by the action of wind or frost firm them up with your boot.

Pigeons can will be getting hungrier this time of year and may turn their attention to your broccoli. Netting is the only answer here and highly recommended if you have a pigeon problem. You will see sharp v-cuts in the edge of the leaves made by their beaks if this is your issue.

Harvesting Broccoli

Harvest your broccoli when the purple heads appear and well before they turn to yellow flowers. When they first start to produce you'll probably be wondering was it worth the wait as you'll have a couple of little purple heads poking out of a lot of greenery. Don't worry, they'll keep producing new shoots when you cut them. Your plants will start to produce in February and can sometimes keep going as far as May.

Broccoli floret beginning to flowerThe shoots can be cut at about 15cm long. It is very important you don't let them go into flower so even if you don't want to eat them straight away (Which is unlikely!) harvest them anyway to keep the plant productive. You can see the broccoli in the picture just starting to flower, off with its head!

If you have too much you can store it in a plastic bag in the fridge for a few days or blanch it and stick it in the freezer.

By the way, you can also eat the broccoli leaves, it seems a shame to waste the goodness in them. Chop them up and stir fry them with some tahini and a squirt of lemon juice.


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