Early strawberries are one of the great pleasures of having a tunnel or glasshouse. Whether from pots or border soil, they taste like a promise of summer and so much fresher than shop-bought ones. Tidy up the plants, removing any dead leaves and bits. Check potted plants for vine weevils. Cut off any runners to divert the plant’s energy from growth into filling fruit. Keep the plants watered and give them as much light as possible, giving them some liquid feed as per the instructions on the packaging. Ventilate on sunny days to keep the temperature cooler and less stressful for the plants, and reduce the danger of fungus diseases. The flowers are more frost-sensitive than the leaves, so protect them from frost with fleece or cloches on cold nights. You will need to hand-pollinate the flowers as fewer insects visit plants under cover. Brush the flowers gently with a soft brush or cotton wool to transfer pollen from one flower to another. You need to repeat this on a number of days to ensure that each flower is fully fertilised and will form a complete strawberry. Continue feeding and watering, and watch out for pests such as aphids and slugs. Remove and destroy any mouldy fruit or leaves to prevent disease spreading. Pick and enjoy the fruit as soon as they are ready, but if slugs are a problem pick them a bit sooner and let them finish ripening in the kitchen.

Garlic has many health benefits, and growing our own is easy when you know how. Homegrown garlic has only the chemicals you apply, and you can eat the leaves and flower-stems when they are young. Planting garlic in a tunnel or glasshouse now can give you bigger and earlier bulbs than outdoor crops, but even starting a crop in modules or pots under cover and planting it out later gives some benefit.  It stops the birds pulling them up too.

The ideal soil for garlic is light, well drained, moderately fertile and neutral or alkaline. Wet sticky clay can rot the bulbs and very rich soil encourages leafy growth at the expense of the bulbs.  A good supply of potash helps, so dig in some wood ashes before planting.  Garlic needs a long, cool growing season and a cold spell to stimulate maturity, so autumn planting is ideal.  However, you need to choose your material carefully.

Do not plant shop-bought garlic and expect a decent crop; you may be lucky but it is sold for eating rather than planting and may be treated to inhibit growth, or carry plant diseases that will persist in your soil for many years. Get disease-free sets of varieties suitable for autumn planting from a garden shop or centre.  Gently split them into cloves, and plant the bigger ones 2-5cm deep into the soil 15cm apart, in rows about 30cm apart, with the pointy end up and the flat base down.  Plant the small cloves close together to produce leaves like chives.  Water the crop lightly and let it dry out between waterings to prevent rotting.  Dig up the bulbs gently when harvesting, and avoid pulling them.  They bruise easily and then will not keep.  Dry and store them in a cool, airy place.

Mizuna is one of the oriental greens that Europeans should grow and eat more. It’s best grown rather than bought because it needs to be eaten right after harvesting for maximum flavour and nutrient value, though it will keep for a couple of days in the fridge.  Like lettuce, you can sow seed little and often all year round in a glasshouse or tunnel.  September sowings will produce deeply cut leaves up to April or May: single leaves can be cut off after about three weeks and whole heads after six to eight weeks.

Mizuna likes moist rich soil, so dig in plenty of compost or other organic matter before sowing. Sow the seed about a centimetre (half an inch) deep in drills about 30cm (12 inches) apart.  Protect the seedlings from slugs.  Keep it well watered and ventilate on sunny days – it is prone to bolting in hot dry conditions.  If it does bolt remove the flowering stems right away to keep it leafy and sow another batch to replace it.  Don’t worry if it wilts after a frosty night: it is hardy and usually recovers.  It is a member of the cabbage / brassica / crucifer family so don’t sow it in the same ground as any of its relatives for at least three years to prevent disease build-up

Mizuna has a milder flavour than either mibuna or rocket, and is good in mixed salads. Like spinach it can be steamed, boiled or stir-fried but it shrinks a lot, so harvest plenty.  ‘Kyoto’ is a good variety to try.

Pollination occurs naturally outdoors, where wind and insects carry pollen from one flower to another to fertilise them and set fruit. Tunnels and glasshouses shelter plants from wind, and fewer insects go inside so natural pollination is sometimes not enough to set a full crop of fruit.  Incomplete pollination of a flower can produce a fruit that only develops and grows on one side while the other side remains hard and misshapen.  This can be a problem with strawberries.  Peaches, nectarines, grapes, melons and aubergines among others can yield better with help.

Hand-pollination is the answer. When the first flowers are just fully open and conditions are dry, brush over the flowers gently with a very soft brush or a little cotton wool. In the past gardeners used rabbits’ tails, but animal welfare was not a consideration then.  Paintbrushes are a bit too stiff for pollination, but the likes of a camera lens brush is perfect.  Never use one on a lens afterwards, because it picks up oils from pollen that would smear the lens.  Pollen grains have spines for gripping onto hairs such as on bees’ bodies, and they brush off onto the sticky stigmata of other flowers – job done.  It is best to repeat for a few days running to ensure good pollination and catch the later flowers.  Tomatoes are easy to pollinate by vibration; tap on the flower trusses or the supporting canes or wires, or water them from above with a coarse spray of water.

Cold frames are four-sided boxes with transparent covers sloping towards the sun. You can buy readymade ones or easily make your own with new or recycled materials.  They are out of fashion nowadays because more people have tunnels or glasshouses, but still very useful.

You can use cold frames to hold plants for which there is no room in your greenhouse just now. They are good for hardening off vegetable plants or half-hardy annuals raised in the greenhouse before planting them out in the garden.  You can sow seeds earlier than possible outdoors if greenhouse space is not yet available, or quarantine new plants, or keep plants that need warmer or cooler conditions than you have in the greenhouse.  Cold frames are good for rooting cuttings, or warming up water or potting compost before use.  If you need an extra degree or two of frost protection for plants inside the greenhouse, you can put a lightweight cold frame over them for the night.

Cold frames are best placed near your greenhouse for convenience, and facing as near south as possible. Their south walls should be low enough to let in the sun.  To ventilate, prop open the downwind side of the top cover.  If you raise its upwind side, a gust could flip it off, and if you slide it the gap may be on the wrong side letting in chilling draughts.  It is harder to control their temperature due to their small volume, so you must anticipate the day’s weather and ventilate accordingly, closing the cover at night.  If you expect hard frost, lay a quilt of weighted bubble-wrap or sacks stuffed with leaves over the cover for extra insulation.  Water plants in the mornings to let the leaves and soil surface dry off before night.