Bred by, and named for the University of Massachusetts, Waltham Field Station, Waltham in the US, Broccoli Calabrese ‘Waltham’ was launched in 1950. It has been a favorite ever since.
Waltham was developed to withstand the increasing cold of autumn. It can survive the cold temperatures of autumn right up to a hard freeze.
This green Calabrese type produces high yields on compact plants over a long autumn cropping period. It lacks the uniformity of an F1 but produces good sized heads and is a good cultivar for freezing. It can survive dry spells and is best for late summer to autumn harvests.
Waltham is well known for its fine dark blue-green main head, but also for its exceptional side shoots, The main head grows to around 10 to 20cm (4 to 8in), once harvested, it continues to produce large crops of side shoots which are tender and tasty.
Calabrese & Broccoli is a confusing series of plants:
Supermarkets have helped to confuse the issue of what is broccoli and what is a calabrese by calling both by either name. Most ‘Broccoli’ sold in the supermarkets is actually Calabrese not broccoli.
Broccoli has small heads (mainly purple, sometimes white or green) which mature slowly and can occupy the ground for almost a year. (The word broccoli means 'little sprouts' in Italian). Calabrese are smaller plants that produce larger crowns.
Keep in mind is that broccoli is an over wintered crop but calabrese produces its crop the same year before winter. Sprouting broccoli can be harvested from late winter to late spring. Calabrese can be harvested from mid-summer to mid-autumn. If you grow both calabrese and sprouting broccoli, your kitchen will be kept in broccoli for most of the year.
Prepare the site:
All brassica crops grow best in partial-shade, in firm, fertile, free-draining but water-retentive soil. Avoid shallow, sandy soils, and exposed sites
Start digging over your soil in autumn, removing any stones you find and working in plenty of well-rotted manure or compost. Tread on the soil to remove any air pockets and make the surface very firm. Brassicas will fail if the soil is too acidic so add lime to the soil if necessary, aiming for a pH of 6.5.
How to sow Broccoli Calabrese:
Sow early and you will miss the first caterpillars. Early crops can be enhanced with the aid of crop covers. Plants should be spaced 30cm (12in) in all directions. Lower crop density gives a longer period of harvest, as more secondary heads are produced.
Expected germination time 7 to 12 days, depending on soil temperature.
Sowing Indoors: Early March to mid July
To get an early crop in June, sow under cover in modules or sow in a seed bed outside from mid to late March until the end of May. Plant out in April with fleece protection. (It dislikes bare-root transplanting). After a few months, when your seedlings reach 6 and 8cm high (2½ -3in), they're ready to plant outside. Water the day before moving, and keep well-watered until established. Space plants at least 30cm (12in) apart and make sure you dig a good deep drill (2.5cm) to give them good anchorage.
Sowing Direct: April to June
Seeds can be sown direct in April to June. Sow seeds thinly about 12mm (½in) deep. Sow thinly, as this reduces the amount of future thinning necessary and potential risk from pests.
For a Polytunnel: Sow March to October
Broccoli calabrese is one of the most successful winter crops for a walk in polytunnel. Sow a few seeds in modules every six weeks from March to August and plant a short row when there’s room. In September and August, sow a few seeds directly and thin to 30cm (12 in) apart. Leave them to grow undisturbed through the winter. Autumn sown crops will be ready to pick in March to June.
Once the plants are in the ground the process is easy. Just let them stand and protect them from the eggs of Cabbage White butterfly. Remove any yellowing or fallen leaves and burn them to prevent fungal diseases setting in. Being a shorter-term crop, it is less likely to be troubled by aphids or caterpillars
Harvest: Late winter to late spring.
The heads must be cut whilst in tight bud; once per week in cool weather, twice a week is essential in warm weather, as this encourages the side shoots to develop quickly. Use a sharp knife and leave a small stalk. Pick the side-shoots regularly (when about 10cm (4in) long. Regular picking can extend cropping time for up to eight weeks. Don't get carried away and strip plants entirely in one go.
Steam rather than boil to keep their rich colour and vitamin count. Leaves also can be cooked and eaten as a winter green. Fresh florets will keep in the fridge for around a week but are also great frozen.
Broccoli is one of the few vegetables to skyrocket in popularity in recent years, mainly because of announcements by medical research groups that eating such cruciferous vegetables as broccoli helps significantly to reduce the risk of cancers.
Rotate your crops, planting brassicas, of any kinds, in the same ground more often than once every four years runs the risk of club root infestation and once you have it, the ground is useless for up to a decade. Don't take needless chances, even with "catch crops" of radishes.
Broccoli evolved from a wild cabbage plant on the continent of Europe. Indications point to the vegetable's being known 2,000 years ago. Broccoli grew wild on the shores of the Mediterranean sea and since the Roman Empire has been considered a uniquely valuable food among Italians.
It can be traced to France in the 1500s, England in the mid-18th century and began to be cultivated commercially in the United States in the 1930s.
Because broccoli was developed in Italy, the plant was named by botanists as Brassica oleracea variety italica.
The Latin name Brassica derives from the Celtic ‘bresic’. The species oleracea refers to a vegetable garden herb that is used in cooking,
The word broccoli is from the Italian plural of broccolo, meaning 'little sprouts' in Italian referring to the flowering top of a cabbage. The large heading varieties of broccoli are sometimes named calabrese after the region of Calabria in Italy.
Broccoli is the leading member of the nutritious cruciferous family of vegetables, so named for their cross shaped blossoms.
|Packet Size||1 gram|
|Average Seed Count||350 Seeds|
|Common Name||Green Broccoli, Heading Broccoli
|Soil||Firm, fertile, free-draining but water-retentive soil.|
|Season||Spring to Autumn|
|Harvest||50 to 70 days from sowing|
|Time to Sow||March to June (up to October in a Polytunnel)|
|Germination||7 to 12 days, depending on soil temperature.|