Growing Cauliflower in Tasmania (my way)
Cauliflower (Brassica oleracea, Botrytis group) is one of my favourite vegetables. It prefers the cooler weather but a summer crop is possible in Tasmania. Cauliflower has a distinct nuttiness and is similar to broccoli in flavour. The main edible part of the flower, of which we don’t want coming too soon before the seedling sizes up (Something that can happen if planted too soon and not protected from frosts).
I am often asked how I grow Cauliflowers from customers. The most heard comment is Í can never grow Cauliflower. Well cauliflower is certainly not the easiest vegetable to grow, because it is very sensitive to temperature changes. However, there are a couple of things that you can do to significantly increase your chances of growing consistently high-quality flowers in your garden.
The biggest factor I have found over the past 15 years is selecting the best variety. Snowball was pretty decent 20 years ago, but last year (2020 winter) I grew 20 ‘Snowball’, 20 ‘All Year Round’ and 20 ‘Snow Crown F1’. Of these, none of the Snowball where worth the effort, half of the All Year Round were ok (the other 10 rubbish) but all 20 of the Snow Crown F1 where large and as you expect of a cauliflower. This tells me that the seed collectors around the world are no longer saving the open pollinated seed to a high standard for these mass produced and cheap seed. It seems these days that we gardeners are doomed just by selecting a variety of a poor strain. We then think it is our fault when it isn’t.
Note on coloured cauliflower. The purple varieties get their colour from anthocyanin, an antioxidant. Unfortunately, both the colour and (I am informed) the benefits disappear with cooking. Orange cauliflower is the result of a mistake (a mutation). It gets its colour from an increased content of beta-carotene.
Cauliflower plants like cool (but not cold) weather and are best planted in mid to late summer (for an autumn and winter harvest). I find sowing seed in November and December produces solid cauliflower also, however you need to water plenty and keep the DIPEL spraying up (natural bacteria to control white butterfly) or net. In fact, this needs to be done to manage your late summer plantings also until it is cold enough for the butterfly to disappear.
Spring plantings are possible if you are prepared to protect with fleece from frosts, Otherwise I recommend waiting until October to start seeds at the earliest. Frost free areas can sow September (The aim is to get them finished before the end of December when it may get hot – I say may!!).
Cauliflower has a moderately slow growth rate and are ready to harvest in two to three months from planting, depending on the variety.
Start seeds indoors about four weeks before your average last frost date (early to mid-October is my average last frost date). Cauliflower seeds will sprout faster if they are kept warm, at 18 to 21 degrees Celsius. I have the benefit of a large hotbed for my business, but any small hotbed helps where tomatoes etc may be started off. They will germinate just fine, albeit a bit slower not on a hotbed but just in the hothouse. If you sow direct, a cloche tunnel or fleece is recommended prior to last frost as the frosts will encourage the young germinating seeds to bolt (go to flower quickly).
Cauliflower plants are biennial (two-year life) typically grown as annuals. However, if you want to save seeds, you will need to leave some plants unharvested, perhaps over the winter, with some protection from the cold.
Cauliflower needs an organic matter rich soil, with a soil pH between 6.0 and 7.0. Well-draining soil is a benefit (as it is for most vegetables), but the 2nd biggest tip in growing cauliflower is that they need consistent moisture. This will help ensure a nice tight large head.
Without sufficient water, the heads turn bitter. Provide at least 2 heavy drenches per week when there is no rain, and make sure it is soaking 15 cms deep. Leaving the soil dry in hot weather will cause the flower buds to open slightly (referred to as ricey heads).
Cauliflower likes cool weather but is sensitive to hard frosts which can damage the flower head. It suffers in temperatures above 26 degrees. Tasmania is an ideal climate for growing them. When planting in the November to January time, some mulch helps keep the soil temperatures lower.
Since cauliflower takes quite a while mature, I water with Seasol, Fich emulsion and Powerfeed every 3 weeks over the growing season. My beds have compost added at the end of winter but I add some more at planting time and if on hand, some cow or sheep manure.
White cauliflower will need to be blanched if you want it to remain white. If you don’t blanch, I have not noticed any flavour change, it just turns its natural yellowish-brown. I blanch by folding some of the larger leaves over the head and tuck or secure them on the other side. Some clips help, string, clothes pegs, anything to keep the leaves on place. Don’t blanch the leaves too tightly; block the light but leave room for the head to expand. The coloured varieties do not need blanching. Plants maturing in mid-winter seem less affected and I have not bothered blanching in June/July with the Snow Crown variety. Although a hard frost may cause some damage to the flower of some varieties.
Last year I imported a variety called ironically ’Amazing’ as it is recommended as a superior open-pollinated cauliflower grown in Europe and North America. This winter is the first time I have grown it and I have been happy with the results. It is slower to mature than the Snow Crown hybrid so planting no later than mid-February would be advised in many areas of Tasmania. Next season I will have to grow 100 of these in order to save plenty of seed. The benefit over the hybrid Snow Crown.
So, if you want to greatly enhance your success with Cauliflower, I would start with Snow Crown F1 or a few other hybrids out there. Not cheap seed but the quality is there. I can’t remember the last Snow Crown that has failed me so if this one doesn’t work for you then it is likely the timing of planting (is frost hitting it in Spring), watering (a big reason) or your soils.
Happy cauliflower growing