I’ve never had much luck with plants in the cabbage family other than sprouts and kale. The biggest cauliflower I have managed to grow was smaller than a tangerine. I always live in hope however and I planted a few unsuccessful (again) cauliflowers this year but the one success was my green spouting broccoli.
Allotment growers may be more used to growing purple sprouting broccoli which keeps the self sufficient in veg during the early spring hungry gap when last years plants are finished and the new ones not yet ready.
What is a little less grown are the green summer equivalents which you are starting to be able to buy in supermarkets too. Slightly less bitter than their purple sprouting cousins they may also be more palatable to people that do not like bitter veg, however it should be noted that it is the bitter compounds in brassicas that give them their anti cancer properties so it may be time to get used to it and chow down!
The calabrese I grew was Green Sprouting which grows a larger central head but then when that is removed has a secession of smaller, long shoots which just keep coming through out the summer. Certainly this was one of my highest yielding plants on the plot this year, probably giving 10 -12 servings of broccoli over the summer from two plants.
For us who prefer not to grow F1 varieties as well it is good to note that unlike many modern plants in the cabbage family this is not an F1, in fact it is an Italian hierloom variety so you can save your own seed.
In the kitchen
The best use of sprouting brocoli is lightly steamed for 5 minutes and served with butter or olive oil and a sprinkling of salt. You can also use it in stir fry.
Yield and plant health
Three plants should provide a small family with a serving a week from August to September. The plants I grew actually started a little earlier and were still producing heads in late October. This variety has all the usual problems of cabbage white and has no resistance to club root.
Kings Seeds (UK)
You can start calabrese in pots in a green house or outdoors. Sow in Spring from March all the way up to early summer, 2cm deep. In pots sow 1-3 seeds in a 3 inch pot. Outdoors, sow thinly in rows 15cm apart. Thin seedlings to one every 7cm or 1 per 3 inch pot. Water lightly until it is time to plant out.
Brassicas can fall victim to cabbage white butterfly or birds so make sure you have a netted area prepared to keep them safe. The plants must never touch the outside of the netting as butterflies can lay their eggs still. Calibrase will reach up to 3 ft high and 2ft across.
In April/May once the plants have several true leaves plant out in final positions. Kale are not too fussy about where they go but they do need a firm soil so you might struggle with a very sandy soil. They will appreciate a feed of blood fish and bone or another organic fertiliser in the spring and a mulch to conserve water.
Pot grown plants will need a period of a week being moved outdoors during the day and brought inside at night to harden off. Plant 60 cm apart, firming in well to stop the plants rocking in high winds water in well and make sure that they are well watered until established. After this water only if it has been dry for several weeks.
Calabrese is a hungry plant and will benefit from a high potash feed to help them flower but also a high nitrogen feed when they are small. I tend to use mulch and homemade compost for the nitrogen and a seaweed feed for potash.
Once they start sprouting keep picking, try for twice a week minimum to keep the heads coming. Try not to let them flower (when the little yellow blooms show). Although they are edible blooming may halt production of other heads. When they have stopped flowering it is worth leaving them as they may re-sprout later in the year.
The main issues with all brassicas are
Cabbage white butterfly/birds – Net from the moment that plants are in the ground. Make sure the plants never touch the sides
Slugs and Snails – These can menace small plants. Use nematodes applied in spring or slug traps.
Club root – Plants will appear stunted and start to wilt. When you pull the plant up you will see swollen stunted roots caused by a bacteria. Burn the plants or dispose of in your council green waste. Disinfect any tools or shoes that have gone on infected soil to prevent the spread. Plant only clubroot resistant varieties and rotate crops. Do not plant brassicas in infected soil for 20 years.