Growing Purple Sprouting Broccoli For Winter Harvest

Broccoli is a very useful vegetable because it is a winter crop, and tasty, new spears (often called cut and come again) will keep on growing if you cut the shoots regularly.

So, unlike most other vegetables, you can enjoy homegrown broccoli in winter, which is amazing.

In this article we will focus on growing purple sprouting broccoli for harvesting in the winter, because it is also good for you, containing carotenoids, folic acid and vitamins A and C. And there is nothing better on a cold winter’s evening than a purple sprouting broccoli and kale gratin. Delicious and so good for you.

Which Variety Is Best For Growing Purple Sprouting Broccoli?

Most purple sprouting broccoli seeds you can buy are generic purple sprouting broccoli plants. 

However, there are some heirloom varieties as well as F1 varieties that you should try.

Generic Purple Sprouting Broccoli

Purple sprouting broccoli is one of the very earliest varieties. Harvesting can begin from February until late spring. This is especially useful as you can harvest when no other crops are growing in the garden. 

Red Arrow

This is an easy-to-grow variety that will produce dark purple spears with a great flavour. It has been awarded the RHS Award of Garden Merit. Red Arrow will be ready to harvest in February and March.

Purple Rain

This British-bred variety will produce tasty tender purple spears and will retain the colour when steamed. Purple Rain will crop from July to November, if you plant it successively.

Now that we have recommended some varieties to try, let’s get down to growing purple sprouting broccoli.

Sowing Your Seeds

sowing carrot seeds

Depending on when you want to start harvesting, you choose the time you start sowing. If you want to harvest homegrown broccoli spears in early winter, start sowing in March.

Sow your seeds in April, if you want them to start cropping in late winter, as in January. Check your seed packet to be sure.

Sow the broccoli seeds in seed trays or small pots. Fill them with good quality seed compost, then make a 1.5cm (0.75in) hole. If you put two seeds per hole, you have a higher chance of one of them germinating. Cover the seedlings with soil.

If both germinate, you can either grow on both or discard the weaker seedling.

Growing Tip: Water the compost before you sow the seeds, this will ensure the seeds won’t get washed away to the edges of the pot. Then spray the topsoil with water from a spray bottle.

Place the seed tray or small pots in a propagator on the windowsill. The ideal germination temperature for broccoli is between 21°C and 27°C.

Once the seeds have germinated, place the pots on a cool windowsill, cold frame or unheated greenhouse. Because the seedlings need a cooler temperature. 

If you don’t have space to sow them indoors, but you still want to be growing purple sprouting broccoli, you can sow them outdoors.

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Sowing Outside

If you are planning on growing purple sprouting broccoli fully outside, you can sow them in a seedbed. 

They will then germinate once the soil is warm enough and this will make them more resistant to cold weather. 

You can, of course, also sow your seeds in the final spot where you are growing purple sprouting broccoli, if you have the space.

In my opinion, transplanting them is better, because you’ll be able to set the roots of the seedlings slightly deeper into the soil, giving them stronger roots and more resistance to the wind.

If you are sowing your seeds outside, keep in mind that they will be more vulnerable to pests such as pigeons and slugs and snails.

Whichever way you choose, start to thin them out as they appear, otherwise they’ll become weak and leggy.

Growing On Your Seedlings

broccoli seedlings

Once the seedlings are big enough to be handled, transplant them to bigger pots, around 9-10cm (3-4in). 

Transplanting them into bigger pots will allow them to grow stronger and develop a good root system before you plant them in their final position.

Prepare The Soil

Before you plant your purple sprouting broccoli plants out, you have to prepare the soil. Broccoli plants need well draining, fertile soil. The soil is one of the most important factors when growing purple sprouting broccoli.

Remove any big stones and weeds, then mix in organic matter. This is important to ensure your plants have plenty of food over winter and improve water retention.

You also want to check if your soil is acidic. Because broccoli, like other brassica, won’t like that. You can check the pH level of your soil by using a DIY soil pH test kit.

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If the test shows that you do have acidic soil, you should mix in lime, which will increase the pH level of your soil.

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After you have added organic matter, such as manure, and lime, if necessary, firm up the soil by walking on it. Broccoli likes firm soil.

Sprouting broccoli likes a sunny, sheltered position. Avoid sites that are low-lying or those that can get waterlogged in the winter.

Transplanting Your Seedlings

Once your young purple sprouting broccoli plants have reached a height of 7-9cm (3-4in), they are ready to be planted out.

Make sure you transplant the seedlings with a good-sized ball of soil around the roots. If the soil is dry, dig a hole for each plant and flood it with water before you transplant them.

Alternatively, a rainy day is a good day as far as transplanting is concerned (but a bit more uncomfortable for you). You’re aiming for a row of plants that are about 60cm (2 feet) away from each other, in rows that are 60cm (2 feet) apart.

Once you have transplanted your purple sprouting broccoli plants, give them a good soak.

Caring For Your Broccoli Plants

In this guide about growing purple sprouting broccoli, we will also show you how to care for your plants once they are in the ground.

Keep your plants well-watered and free of weeds as they start to grow. You could add a mulch (a covering of grass cuttings, for example) around the base of each plant to make life easier for yourself.

Don’t be tempted to add extra food to the soil at this stage, as it will lead to soft and leggy growth. In the autumn, earth up around the stems, packing extra soil gently around the base of the plants to a height of 9cm (4 in). This will give the plants more stability if it gets windy and will also help protect against frosts.

If your purple sprouting broccoli plant does not produce buds, then it does not have enough nutrients. Simply feed your plants with a liquid fertiliser.

As you can see, growing purple sprouting broccoli is easy.

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Harvesting Your Winter Crop

harvesting your winter purple sprouting broccoli

Now we come to the best thing about growing purple sprouting broccoli, picking them for the kitchen.

Depending on the variety you grow, you could start harvesting as early as October or November, and by January/February at the latest.

Cut a broccoli spear (otherwise called curd or flower bud) when it is about three inches long and before the flowers open. If you let them flower, the plants will stop producing.

Cut the central, larger spear first and then pick the smaller, side shoots on a regular basis. Don’t pick all the spears from a single plant at once – cut from across your crop to give plants time to recover and grow more.

Pests And Diseases Affecting Purple Sprouting Broccoli

caterpiller damage on brassica

No guide about growing purple sprouting broccoli would be complete without having a section about pests and diseases. Because some of them can ruin your entire crops and with it, all the hard work you have been putting in.

Diseases

Like for all plants of the cabbage family, broccoli is susceptible to some diseases.

Brassica club root is one of them. It’s a fungal disease that infects the roots of broccoli plants and other brassicas.

This disease is soil-borne and occurs in wet warm weather, which means in mid-summer to late autumn the risk of an infection is the biggest.

The fungus is attacking the root, which means it will inhibit the plant from getting nutrients and water to the stem, leaves and curds.

The first signs of an infection you will see is slow or stagnant growth. The leaves will turn a purplish colour and might wilt in hot weather. If it gets cooler, it might look like the plant has recovered, but this will not last.

To be sure, you have to dig the plant up, because the surest sign of a club root infection is a hugely swollen root system. The thinner roots might have died off.

Once a plant is infected, the yield will be reduced considerably and the plant might even die.

A club root infection can ruin all your efforts you put into growing purple sprouting broccoli.

There is no cure for this disease, so prevention is the only way. These measures can help to prevent an infection with this fungus:

  • make sure you buy seeds and plug plants from a reputable supplier who can guarantee that the products are not infected
  • Ensure that there is good drainage as this will minimise the risk
  • Give your plants enough space to ensure good air circulation
  • Water from below to keep the foliage as dry as possible
  • The fungus prefers acidic soil, so liming when you prepare your soil can help to reduce the risk
  • The stronger and healthier the root system of your purple sprouting broccoli plant is, the less likely it is that an infection occurs. To give the plants the best chance, plant them out a bit later, when they have grown more
  • If you know that the disease is present in your soil, consider crowing your broccoli in containers
  • The disease can be spread through tools and boots, so if you have infected soil, clean everything before using it on a non-infected bed/patch
  • weed regularly and remove dead plant debris

Downy mildew is another disease caused by a fungus-like organism. 

downy mildew on tomato plant

This organism will attack the leaves and is most prevalent in wet conditions and tends to strike from late spring to early autumn.

It is easy to spot when the disease has infected your plants. Young plants and seedlings will be covered with a white fuzzy layer which looks like mould. The plant will die quickly once infected.

More mature plants will get yellow marks on the top of leaves and white fuzz on the underside of leaves. The infected foliage will wilt, die and fall off.

Like with most diseases, downy mildew cannot be cured, but there are things you can do to prevent an infection:

  • practice crop rotation to avoid a build-up of the disease in the soil
  • keep the bed/veggie patch weed free and clear any dead plant debris immediately
  • plant your purple sprouting broccoli well apart to allow for good air circulation
  • remove infected plants immediately and destroy
  • water from below

White blister is caused by a relative of the organism that causes downy mildew and both diseases often occur together. Like its relative, this organism also likes wet weather, so the risk of infection is highest at the same time. 

The first sign you will spot is whitish patches on the underside of the leaves of your broccoli plant. These will then develop into white blisters, hence the name.

You might also notice a discolouration around these blisters, which will also move to the stems, flowers and spears. The infected parts of a plant can also become distorted.

The measures to take to prevent an infection are the same as mentioned above for downy mildew.

Brassica black rot could also affect your broccoli plants. It’s a bacterial disease that also thrives in warm, wet conditions.

The symptoms of this disease are yellow and brown patches, that are V-shaped. It will start on the outer leaves and move inwards. These patches will grow until the whole leave turns yellow and brown.

This disease will kill seedlings and young plants quickly. Mature plants might survive, but they will produce a lower yield.

There is also the risk of spreading the disease to other susceptible plants. So it’s best to pull up and destroy any infected plant immediately and destroy it.

There is no cure, especially, because you will only see any signs when the plant has been infected for at least a week. Prevention is the best solution:

  • buy seeds only from reputable suppliers that are guaranteed to be disease free
  • If you save seeds, don’t do it with infected plants
  • practice crop rotation
  • water from below
  • space out your plants to allow for good air circulation
  • keep your beds weed free and remove dead plant debris immediately
  • pull out and destroy infected plants immediately

It might sound like growing purple sprouting broccoli is difficult, given the number of diseases that could affect it. However, the preventative measures for all these diseases are the same.

So it will be easy to minimise the risk of your plants getting infected.

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Pests

pigeon on garden fence

Like with diseases there are also quite a few pests that like brassicas.

Birds, especially pigeons, are one of these. They can destroy your entire crop within a few hours. And I have learned this the hard way.

Pigeons love brassicas and especially seedlings and young plants. So you need to protect them.

This is easily done by covering them with netting to keep the pesky pigeons away.

Slugs and snails also love young brassica plants. I don’t recommend using slug pallets, as these kill them. And slugs and snails are very important for our ecosystem.

To keep your seedlings safe, cover them with half a plastic bottle. Squash bottles work best. Just cut them in half and put the top half over your young plants. 

Top tip: but a piece of netting over the bottle top to make sure the slugs and snails can’t get in.

The cabbage white butterfly loves to lay its eggs on brassicas like broccoli. Their caterpillars will then devour your purple sprouting broccoli.

There are actually two species, the large and the small white butterfly.

You might be able to see these caterpillars on your plants. The caterpillars of the large white butterfly are yellow and black. The ones of the small white butterfly are pale green. 

They leave holes in the leaves as they eat them, so this is another sign.

The best way to keep these caterpillars away from your purple sprouting broccoli is by keeping the female butterflies from laying their eggs on your plants. This can be achieved by covering them with insect-proof netting between May and October.

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The cabbage moth also likes to lay its eggs on brassicas. Their caterpillars are yellow and green or brown.

Again, cover your plants with insect-proof mesh to protect them.

The third animal that lays eggs on brassicas, such as broccoli, is the diamond back moth

Their caterpillars are green and can grow up to 1cm long. Insect-proof netting will also keep your plants safe from this pest.

The cabbage root fly is another pest that can affect your broccoli plants. They look like houseflies and the females lay their eggs in the soil under the plants.

Their offspring, white headless and legless maggots, will then feast on the roots. This can lead to young plants dying, and mature plants will grow slower and produce fewer crops.

Insect proof netting will also work to prevent the cabbage root fly to lay their eggs under your broccoli plants.

With all these insect pests, there are other ways to control them. One of these is companion planting. This is an organic gardening method, where you plant different plant species together for a mutual benefit.

Many plants deter pests, such as garlic, onion, chives, many herbs. The scent of these plants will either repel the pests or confuse them so that they won’t find your purple sprouting broccoli plants.

You can encourage natural predators to your garden, such as ladybirds, hoverflies and lacewings, ground or rove beetles. Many plants, such as marigolds, yarrow, thyme, chives attract these beneficial insects. 

To attract beetles, provide them with the right habitat, such as compost heaps, log piles and leaf litter.

Now that you have read our guide on growing purple sprouting broccoli, you are ready to give it a go. Happy Growing!

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