Brussels sprouts are easy to grow from seed and produce an important and highly nutritious crop during the winter months. Incredibly hardy, they taste even sweeter in the face of hard frost. We asked experienced allotment grower Lee Senior to share his expert advice on successfully growing Brussels sprouts. Here are his top tips.
Do you want to try it? Browse our full range of Brussels sprouts seeds.
How to choose the best Brussels sprouts to grow
Flavor is an important consideration with Brussels sprouts, perhaps more so than with other vegetables. Historically it was the bitterness of some varieties that caused people not to eat them. Most of us can probably remember eating sprouts for the first time in our childhood, and, in some cases, never forget! These days, things have changed for the better. Granted, you might not want to eat them before a job interview, but I’m a big fan of sprouts. They are a reliable winter staple and I couldn’t be without them in my Christmas dinner. Today the modern varieties taste much better and the bitterness is gone!
Another consideration when growing sprouts is when you would like to harvest them. Early varieties such as F1 ‘Crispus’ can be ready by mid-September. I have grown this in my allotment more than any other species over the years and have had great success with it. F1 ‘Brigitte’ is also a good tasting early bud that is ready from October to mid December. Another favorite of mine, very reliable.
If you want shoots for Christmas then the mid-season variety is best. F1 ‘Brenden’ fits the bill perfectly. It holds very well and is a heavy crop that can be harvested from early November to early February.
If space is tight, or your space is airy and exposed, the semi-dwarf ‘Long Island’ is the way to go. This variety is shorter and sturdier than the standard variety, reaching over 2ft (70cm) in height instead of 3ft (90cm) in height. It has a long harvest period, usually from the end of October to the middle of February, which is very useful to continue.
How to sow Brussels seeds
Brussels sprouts are slow growing and require a long growing season. Accordingly, the seeds should be sown under cover in late February or early March. Start seeds at a mild temperature of 15C-18C (59-64F) in small pots or root trainers filled with multi-purpose or seed compost.
Plant the seeds lightly, just below the surface of the compost, and cover with vermiculite or a thin layer of compost. Firm gently and wait for germination which should take 7-10 days. I use a heated propagator or a windowsill, but you can keep them in a cooler if the weather is warm enough.
After germination, wait until the first set of true leaves appear. At this stage, I prefer to plant the seedlings in 3-inch pots so that they grow into strong plants with five or six leaves and good roots.
If you are growing under glass it is very important that the young plants are not exposed to excessive heat or direct sunlight. This may cause them to stop growing and eventually the plants may fail to grow properly or be stunted.
Brussels sprouts can be sown outdoors in a specially prepared seedbed before they are planted in their final location. Sow at a depth of up to 15mm and germination takes 10-14 days in warm spring weather. Cover the seed holes with multi-purpose compost, or fine soil, and use a thin layer of wool for warmth.
Sowing seeds outdoors negates the need to strengthen young plants, but germination is slow due to fluctuating temperatures. Slugs are also a real danger. I have seen these blade-eating plants devouring young seedlings overnight, almost wiping out the bed. For that reason, I prefer to sow under glass in a more controlled environment.
When and where to plant Brussels sprouts
Brussels sprouts stay in their storage areas for a long time. This lasts between 8-10 months, depending on the variety and growing conditions. This is an important consideration when planning to rotate your crops, as it is not possible to plant the next crop in the same year. That said, I often plant a fast-growing radish plant to get more out of the space. The seedling is ready to harvest in 4-5 weeks and will not disturb the shoots if planted immediately.
When choosing a home for your seedlings, remember that they prefer a slightly heavy, firm and fertile soil with a neutral or slightly alkaline PH. A secure location is required. An important rule is good drainage, as planting in heavy waterlogged mud will lead to problems. Sandy or very light soil is not ideal as plants are susceptible to windblown rock and can be blown away.
Brussels sprouts need a good supply of nutrients and reliable moisture. Adding plenty of well-rotted manure, garden compost or leaf mold is therefore essential before planting. This can be done during the winter if needed.
If you have grown your seedlings under glass, harden them off in late April or early May before planting them in their final locations. Use a trowel and plant them very tightly, not less than 2ft (60cm) apart. Rows should be at least 2.5ft (75cms) apart, preferably space permitting.
How to care for Brussels sprouts
My most important tip when planting sprouts is to firm up the soil around the roots! ‘Putting them in concrete’ was an old saying we were told as students, but we don’t take it literally! Plant the plants in firm soil and use the heel of your foot to firm them up before watering thoroughly. Roots need strong soil around them to produce strong buds. Don’t be afraid to repeat this strengthening process in the fall, if needed, to prepare for any incoming winter weather.
A common problem with shoots is ‘beating’. This means that the buttons are not formed firmly and instead are soft and loose and almost like very small cabbages. If this happens they are still edible and can be treated like small vegetables, but this is not what we really want! One of the main causes of shoots is wind blowing plants and roots are reduced. Firm the soil around the roots periodically as needed to help reduce the risk of this happening. In windy areas I have had to put plants in from time to time to provide stability. Another option is to compact the soil against the base of the stem to stabilize the plant. Other causes of ‘struck’ shoots include poor, infertile soil and drying of the roots.
If your plants are leggy and tend to fall over, you may be planting them too close together, limiting their vigor and growth. The buttons are also likely to be small and can sometimes be blown away. Keep your plants well watered during dry summer weather to maintain plant vigor and button quality.
Common pests that affect Brussels sprouts
As part of the brassica family, Brussels sprouts are susceptible to pests. If you cover the plants with fine netting or butterfly netting during planting, this will prevent the cabbage white butterfly from laying its eggs and any subsequent caterpillar infestation.
Brassica collars are useful in preventing the troublesome caterpillars of the cabbage root fly. This fly, which at first glance looks like a housefly, can also be controlled biologically using a product such as Nemassy. Cabbage root fly, in many cases, will make the plant useless and can be a big problem.
A very small problem, the cabbage whitefly can affect the underside of the leaves. You may see their clouds fly when you shake or tap the plants!
Cabbage aphids are common, especially in mild winters. The good news is that if your plants are otherwise healthy, they shouldn’t be a problem. Aphids can be confused with whiteflies but, in fact, they do not fly when disturbed and often (not always) have a gray appearance.
Soil-borne clubroot disease is a potential problem for all brassicas. Try to choose varieties that show resistance. And plants grown in pots rather than directly planted will do better if this disease is prevalent in your soil.
How to harvest and store Brussels sprouts
The general consensus in allotments across the country is that the flavor of the sprouts is at its best after a hard frost or two. The frost takes the edge off any bitterness in the shoots and in some varieties it even ‘sweetens’ it.
The golden rule when harvesting buttons is to pick them from the bottom of the stem up. This encourages others to develop higher and higher. I have to admit that sometimes I didn’t stick to this when I was given really strong buttons far from the stem, before the smaller ones at the bottom!
The tops of the sprouting plants can be used as a delicious loose leafy green vegetable. Sprouts can be used in the same way, which just goes to show that very little is wasted on the humble Brussels sprout.
Don’t be alarmed if some buttons have a yellow outer leaf or two. I pull them out and sometimes even the outer layer of leaves to reveal the tough green buttons inside. Buttons can remain on the plant for weeks before harvest – especially during cold weather.
Once ripe, the buttons keep well in the refrigerator for about two weeks. Eventually they start to soften a bit but this is a plant that lasts until the end.
We hope we’ve inspired you to try growing your own Brussels sprouts from seed. With a little planning, you might say grow your own Christmas dinner! Find out more of Lee’s practical, practical, DIY gardening tips monthly assignment pages.
Lead image: Brussels Sprout ‘Cryptus’ F1 seed from Suttons
