With leaf vegetables, you have a choice between small, medium or large. Pick large leaves before they decay, and in winter months don’t expect large leaves because few leaves grow beyond a small to medium size when it’s cool and dark. An example is with spinach leaves – they are small and sweet in winter; then, from the same plants, they can grow large, even enormous, in spring. They are very tender, despite being large.

Lettuce offers the best flavour and texture in spring and early summer. This is also its time of healthiest leaf growth, with least mildew on leaves. Leaves of older lettuce plants are likely to be more bitter, and once you see a flower stem it’s best to twist out the plants.

If you like bitter leaves, try growing less lettuce in late summer through autumn, and more chicory and endive. They grow best from sowing in midsummer, not spring, because their flowering season is from late spring to early summer.

Bonus leaf harvests

Carrot leaves are edible – some people turn them into pesto. Beetroot leaves taste like leaf beet, an alternative to spinach although less tender.

Celery and celeriac leaves make a rich stock. Leaves of broccoli and Brussels sprouts can be eaten as greens.

• The only vegetables with poisonous leaves are solanums – tomatoes, peppers, potatoes, aubergines – and rhubarb.

Celery

Summer celery can be harvested small or large. It grows more fibrous with age and rarely suffers disease – frequent watering helps to keep stalks tender. Older plants put energy into sideshoots as well, so the best harvest time is usually three to four months after sowing, when planted at 22–25 cm / 9–10 in spacing.

In damp autumn weather, you may notice a rapid browning of leaves and stems. This is Septoria apiicola, also called ‘late blight’, and it can decimate leaf growth. Other susceptible plants include celeriac, parsnip and parsley – all umbellifers.

Should you notice it on celery, cut heads within a week or two; you then need to trim off much of the outer leaf and stem, which will have turned brown. In areas with damp autumns, grow Granada as your late celery because it has resistance to Septoria.

Leeks

Leeks mature over a long period and can also be eaten small or large. However, there are limiting factors for specific varieties, related to when plants flower in the spring after sowing.

• Summer varieties with long stems suffer frost damage, but only on nights of about –3°C / 27°F or lower. Their harvest period in much of the UK is from about mid-July to November.
• Autumn varieties usually crop from September until year end. They also survive, and even grow more, through mild winters, so they are the most versatile types.
• Winter leek varieties grow more slowly in autumn, have good resistance to hard frost, and are best harvested in early spring. At that time they increase rapidly in size.

Around mid-spring, and governed by day length, leeks initiate flowering and make a stem in the centre. At first this is soft and edible but then, in May, it becomes fibrous. Aim to harvest your last leeks by early May, at which point they will be 13 months old, from sowings the previous April.

Root vegetables have many options for the time and period of picking. They can be harvested at any size, and their flavour changes during each phase of growth.

Worry less about woody roots

There is a misconception that large root vegetables are woody. However, this is not correct! When sown at the best time and grown in healthy soil (fed by nutrients that become available through the work of microorganisms rather than soluble fertilisers), they rarely go woody.

One August, I grated a 0.9 kg / 2 lb Boltardy beetroot that I had sown six months earlier. It was everything you could wish for – juicy, tender, and sweet – and there was a lot of it.

Woodiness of root vegetables is governed less by their age, and more by soil condition and when they flower, as I explain in the following two categories.

Half-season root vegetables

Four commonly grown root vegetables – fennel, radish, kohlrabi and turnip – have two seasons of harvest, with a flowering stage during summer. The flowering process makes roots woody and fibrous, and therefore unpleasant to eat, so it’s best not to wait too long before picking them. The optimum time is when they are swelling, just before the period of summer flowering.

• In many climates, there is time to grow a small harvest from sowing in late winter and picking in early summer, before the flowering process begins and spoils your harvest.
• These vegetables can also be sown in late summer for a longer period of harvest in autumn. Your principal concern as the autumn harvest approaches is not woodiness, but frost – they tolerate some frost, but not too much (see Lesson 16).

Radish include two types: spring and mostly red, small radish, and winter radish roots of many colours. The former tolerate only a little freezing so need harvesting before first frost, to be safe. Winter radish survive lower temperatures, to harvest fresh during winter if it is not too cold.

There are sub-categories here, one being beetroot, which grows well in both a half and whole season. Roots can easily reach tennis-ball size in a half season, and are harvestable at any stage or size.

Half to whole-season root vegetables

Swede, carrot, parsnip, onion and celeriac grow to a harvest from sowings during their best times through spring to early summer. They grow for as much as the whole growing season, and flower the following spring, so they have a long period of harvest from one sowing.

• Sow celeriac early enough for it to grow large, and swedes late enough for plants to survive the insects of spring and summer.

Celeriac is ready for picking from early autumn, and yet the harvest can also double in weight after September. In wet autumns, growth may be compromised by Septoria disease on older leaves (see above).

Carrots are good to pull as soon as you see the first shoulders pushing up a little, eight to ten weeks after sowing. Spacing is important for growing carrots of a decent size; I recommend you thin them by pulling unwanted seedlings four to five weeks after sowing. You want about two carrots per centimetre (five per inch) before the first small harvests, then keep pulling the larger ones to make space for others to grow. One sowing then gives six to ten weeks of harvesting time from thinnings, and another eight to ten weeks of pulling the largest carrots.

Parsnips are usually eaten in winter and grow sweeter in cold weather, but you can harvest them any time you like, say, from September onwards. They resist frost and can store in the ground all winter, unless your soil lies very wet; if so, harvest in late autumn to store in sacks or boxes.

Onions are intermediate, needing between a half and a whole season to mature. Transplants of an early variety, such as Rose de Roscoff, can be ready to pull by early July. You then have time to grow a range of second plantings, including broccoli, carrots, beetroot, radicchio and kale.

Traditional varieties of spring or salad onions, such as White Lisbon, make a bulb if allowed to grow for long enough. You can harvest most of the onions from each multisown clump for use as salad onions and leave a few to continue growing to make a bulb onion, if you do not need their growing space.

It’s not straightforward to judge when onions are best pulled, for a harvest of bulbs to store. There are useful clues, such as a quarter of their stems falling on to the ground, at which point it’s good to fold down all the other stems. Then pull all bulbs a week or ten days later.

When you pull onions, their leaves may still be half green – this is fine. They finish drying under cover, and an earlier harvest allows more plantings to happen in the vacated space.

Potatoes vary in time needed

You can harvest potatoes during almost all of the summer months, and even into early autumn. Timing depends on the type of potato you have grown and on how you like your potatoes to taste.

If you harvest them when the leaves are still dark green, and perhaps before plants flower, the potatoes are smaller and sweeter, soft and with a flaky skin. They are for immediate eating, a luxury early harvest.

For larger amounts to eat, and bigger tubers, look for at least a quarter of leaves turning paler, with some even turning yellow. Most potato varieties also grow lovely flowers, two to four weeks before giving a decent harvest.

If you notice any leaves developing late blight, cut all stems to ground level, straight away – you can put them on the compost heap. Then harvest potatoes on a dry day a week or so later, when blight spores will no longer be present.

• Always cut off any green parts of potato tubers before you cook them – the green area is poisonous.

Tip:

The soil washes easily off root vegetables straight after pulling, when they are still moist, so it’s good to have a bucket and brush in the garden for easy cleaning at harvest time.

However, eating a little soil is good for your gut microbes (many are similar to those found in healthy soil), so there is no need for vegetables to be scrupulously clean; this also saves time.

A heart or head is not an end point, but a brief stage of life for certain plants. The next stage is the growth of a stem inside the heart, which then erupts upwards to bear flowers and, eventually, seeds.

Depending on the vegetable and its sowing date, the seeding part happens within a few months (lettuce), or in the second spring (summer-sown cabbage).

Judging when a heart is ready to harvest is influenced by whether you want to eat it now or later, and how tight you want it to be. Tighter hearts are sweeter, from lack of light to innermost leaves. This blanching effect converts bitter chicory leaves to sweeter radicchio leaves, which are also crisper.

Cabbage

Cabbage can be for leaf or heart. Mostly it depends on the variety you grow but it can also depend on the time of year, because cabbages overwintered as small plants, to harvest in the spring, often make more green leaf than heart.

For cabbage varieties described as hearting, the sweetest and heaviest harvest comes ready when you wait long enough for the visible change of leaf colour at the centre. Heart leaves fold on to each other and turn paler in colour, with enough tight leaves that you can knock on the outside of a heart and feel that it is firm. Once this is the case, harvest by cutting at the base whenever you need the food. In summer, such hearts will not stand for more than two weeks before the outer leaves start to decay. In autumn, you have a possible harvest time of up to six weeks, and storage time beyond that.

For leaf cabbage, usually in spring, cut the whole plant at any stage. Occasionally you may see a flower stem developing, which is good to eat if you cut the whole plant before the stem is too long.

It’s also possible to cut or twist off some larger, outer leaves of cabbage. They are more fibrous and less sweet than inner leaves, so it depends how hungry you are!

Chinese cabbage often folds in rapidly, to make a heart that stands for less time than other cabbage. First you see white leaves at the centre, which is the best time to cut; soon after there is decay on the heart’s outer leaves, and perhaps insect damage too.

Cauliflower

Cauliflowers are at their prime for no more than four to six days in summer, and for up to two weeks in autumn. They are mature when having just emerged from the initial sheath of leaves. Keep checking for curds, as sometimes they are hidden by tall outer leaves. There is no worthwhile secondary growth after this harvest.

Chicory

The harvest options for chicory are bitter leaves at any stage, or bittersweet hearts called radicchios, also ‘chicons’ or ‘endives’, which harvest in winter to early spring. During winter you can also dig up chicory roots for ‘coffee’, from the variety Magdeburg.

HEARTS IN AUTUMN

From June sowings, chicory plants heart in early autumn and often flower within two weeks of becoming firm; whereas late autumn hearts from July sowings do not flower until spring, although a few of their outer leaves may decay after forming.

How well your chicory plants ‘heart up’ depends partly on the time of sowing, but above all the variety. If you grow the TT varieties, you will enjoy a longer period of radicchio harvest because:

• Almost all of the plants make firm hearts.
• Once they are firm, they stand for up to a month without the edges of the heart leaves browning.
• Even when the outer leaves start to decay, there is usually a decent heart inside those leaves.

Radicchios should develop once plants look full size, around ten weeks after sowing. Press the centres of all your plants every few days, to find those with the firmest hearts. There is usually a wide range of harvest dates from one sowing. You can cut a plant whose heart is loose and it will be fine to eat, just less sweet and lighter in weight.

Broccoli

Broccoli stems are delicious. You can choose how long to cut them, whereas in supermarkets you can buy heads only on short stems. Choose your length of harvest season for each planting of broccoli – either remove plants after cutting the main head, or keep coming back every few days for sideshoots. Which of these two methods depends on the variety, the season and whether you need the ground for replanting.

Broccoli is also called calabrese when it grows large green heads during summer and autumn, which have about a week of harvest opportunity. Initially, the buds are tight and the colour grey-green, then the head and buds swell and you may see some yellow in the broccoli. Harvest at this stage, because if left another week there is a risk of flowering.

As it elongates, broccoli grows more fibrous, and there may be some caterpillars and decay inside the harvest. Cutting the main, central broccoli stem will encourage growth of sideshoots.

Sprouting broccoli does not make heavy heads, because the plants are bred to grow many smaller sideshoots over four to eight weeks. These can grow quite long and the stems are tender, with superb and sweet flavour.

• Broccoli Raab is a flowering autumn broccoli, with smalland juicy stems. Harvest when you see yellow flowers.

Brussels sprouts

Sprouts are best picked as soon as they are fully swollen, when they become rounder and a little paler in colour. Soon after that, the small outer leaves start to yellow and suffer insect or fungal damage. They are still edible and tasty, but need more time to be prepared before cooking.

• You can have Brussels sprout harvests for six to seven months by growing two varieties, one for earlier harvests and one for later. I recommend F1 varieties for tight buttons, because many open-pollinated (OP) varieties, which were once good, now are not (as I explain in Lesson 5).

It is best to look in a catalogue or online for the maturity dates that you want. In 2019, I found Marte F1 gave fine harvests from September to December, and Cascade F1 or Doric F1 cropped from November to March. Then, in 2020, Brodie F1 gave excellent early harvests and continued all winter.

Fruiting vegetables do not stand for long in best condition. Sweetness develops slowly and then peaks for a few days only. Sugars then convert to starches as the flesh becomes firmer and more dense. This section describes the changes that happen for different fruiting vegetables when you pick sooner, or later.

• The flesh of a mature cucumber is soft and juicy, and the outer skin and seeds are also soft. Then, after two or three more days, the flesh becomes firmer, the skin harder and the seeds tough to eat.
• Courgettes / zucchini offer the speediest change between small and large fruits, within as little as two days in high summer. To keep them producing small fruits, you need to pick all you see that are at the size you like. Cut the stalk close to the main stem, every day or two, regardless of how many you can eat.
• Other summer squash are best picked every four to seven days, before they have a tough skin and firm seeds.
• Winter squash need to show you a hard skin of mature colour, and a stalk turning yellow, or even brown. Cut the stalk carefully to keep it attached to the squash itself, if you want to store it through winter.

Peas and beans

A big topic, as these are such a staple and delicious food and are also not too difficult to grow. The harvest possibilities are many, and continue over a long period.

PEAS

For peas to shell out, it’s your choice, according to how you like them. Young peas in slender pods are the esteemed petits pois, an early and very sweet harvest, though of small amount. Older peas in fat pods are gradually converting sugar to starch, and gain massively in yield of food.

Mangetout pods are best to eat when harvested before they swell. Otherwise they go stringy, although there will also be sweet peas inside. Sugar snap peas can swell and still have tender pods.

Peas also give the option of harvesting shoots, which taste of pea without much sweetness. If you keep picking shoots, they produce more and more while flowering is also delayed, so that ultimately there are few pods. We make two sowings in early spring: some peas for shoots over a long period through spring, and some peas for pod harvests in early summer.

It can take some searching to find ripe pods of peas and beans, and of new pea shoots. Doing so takes practice, and knowing where to look.

• With peas and beans, the first pods to swell are the lowest ones near ground level, so keep checking thereabouts, and shell out a few if you are unsure what might be in there.
• Shoots are initially at the top of each plant, after which, as sideshoots develop, you find them at all levels. Sometimes they are hidden below older growth.

BROAD / FAVA BEANS

Here we meet a division of opinion – some people like the beans small and tender, while some like them larger.

Some like eating the pods too. My observations are:

• Pods of broad beans are edible when their beans are still tiny, though I find that they don’t taste great.
• Broad bean skin is bitter, and there is proportionately more of it around small beans, compared to the sweeter middles. So in this case, it’s not true that small is sweet.
• Waiting an extra week or two brings you more to eat.
• Fat beans are quite sweet, even when raw, and the contents of just a few pods make a meal.
• Later sowings in May or June give a smaller harvest because growth is somewhat out of season.

In summary, don’t rush to harvest your broad bean pods. Wait until you can feel the decently swollen beans inside them.

FRENCH / RUNNER BEANS

Much depends on your eating preference, whether for small and tender bean pods, or slightly larger and firmer ones. Once any of these plants have started to flower, little bean pods will develop and can be ready to pick within about one week. If left longer, pods become tough as the small bean seeds develop inside.

Another option is to leave pods unpicked until autumn, for harvesting as dry pods with beans inside. Harvest when they become a pale or yellow to light brown colour, even before they are fully dry. In climates with damp autumns, you may need to pick pods that are soft and moist and then dry them in your house. Shell out the beans once the pods are fully dry, and store them in jars – you can then eat them all through winter.

The first frosts of autumn limit the picking time of certain vegetables that are coming ready at the same time, such as celery and Florence fennel. They tolerate only slight frost, and you can also protect them with fleece.

In continental climates, you need to watch for the first frost as early as September, when it can damage tomatoes, other solanums, cucurbits and beans – it only takes one freezing night.

Many root and leaf vegetables, however, are improved in flavour by low temperatures, most notably spinach, Brussels sprouts, kale and parsnips, which are sweeter after frosts. Low temperatures, without a hard freeze, also increase the sweetness of carrots, beetroot, leeks and kohlrabi.

• You can harvest frozen leaves, stems and hearts, should you need to. Allow them to thaw before use, in a cool environment.

See Lesson 16 for more information on frost.