Day length and weather conditions determine how well our crops grow and the recent endlessly cold, wet spell has stressed many of them leading to possible bolting. So be prepared.

Take onions and shallots. You’ll normally get good results when giving them moist, moderately rich ground in a sunny spot. After a March or April planting when soil and air start warming up, the bulbs will start growing, reaching maturity in late summer.

At this stage, you water during a dry spell and keep the ground weed-free to prevent competition for soil nutrients and let the onions photosynthesise efficiently.

After sprouting, onion roots grow from the hard plate at the base of the set. The plant’s outer rings or scales emerge from here and at the top of the set, they produce green leaves for photosynthesis. Fertile soil leads to more and fatter shoots and larger onions or shallots at harvest.

These alliums have an internal clock which identifies dawn and dusk and the plants start forming bulbs when there are 14 or more hours of daylight. They do this by producing inner scales which, unlike the outer leaf-forming ones, don’t emerge from the top of the bulb. They are the heart of the bulb and gradually thicken along with the outer the outer scales, so the better the growing conditions, the larger the final onion.

When you next cut an onion in half lengthways you’ll see these different parts or scales in the bulb.

But the weather hasn’t played ball. The days have been cool and wet and overnight temperatures ridiculously low. There have also been fluctuations that we’ve scarcely noticed. April was cold, May was apparently the warmest on record, and June ridiculously low. My French beans have sulked miserably despite the fleece tent I’ve created round them.

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Cold nights and these fluctuations have stressed many plants, including the onion family, and I’m afraid some will respond by bolting - flowering and setting seed prematurely. You can justifiably blame the weather, not yourself, for this bolting.

All you can do with bolting is remove the offending shoot and lift and eat the plant early. It may not taste quite as pleasant and certainly won’t store.

With the rest of the crop, you’ll find they’ll stop growing in a few weeks, as you’ll see when the tips of leaves start dying. This will happen sooner with shallots than onions.

Keep the onions well weeded to let them ripen well and don’t water, however dry the soil. Lift once the foliage has virtually died back, but don’t bend over the stems, the old-fashioned method which could actually damage the plant and introduce fungal damage.

Lonicera periclymenum 'Serotina’Lonicera periclymenum 'Serotina’ (Image: free)

Plant of the week

Lonicera periclymenum 'Serotina’ is a later flowering honeysuckle with large dark red flowers that are streaked with creamy yellow. Scented, but not quite as strongly so as the native honeysuckle, it usually has bright red berries in early autumn.

Can be grown to scramble through a hedge and I find it goes well with vigorous climbing roses like ‘Rambling Rector’.