Tomatoes, peppers, aubergines and cucumbers will be growing strongly by now. Those that that were started off early will be setting fruit. Ensure that plants have adequate water and ventilation. A guide to watering for tomatoes grown in grow bags or the greenhouse bed is as follows; if the previous day was hot and sunny, give each tomato plant 2 pints of water, but if the previous day was dull and cool supply just 1 pint per plant. Irregular watering can lead to a calcium deficiency in tomatoes leading to blossom end rot of the fruit. If the compost is very acid and low in calcium, scatter a small handful of calcium nitrate (or nitro-chalk) per square metre of bed area and water in.
Ensure that insects can gain access for pollination, commercial growers usually have a bee colony in each growing house.
Continue to support vine tomatoes, climbing cucumbers, and melons by winding round supporting strings or tying in to canes or straining wires. Pinch out side shoots on cordon grown tomatoes, and restrict the numbers of immature cucumbers and melons to ensure that those remaining achieve full fruiting size. Don’t delay in picking any fruit that has matured as this will encourage more flowering and fruiting to follow on. Any delay will cause the plant to ‘rest on its laurels’ and inhibit future flower formation.
Continue with the regular feeding regime. Watch out for magnesium deficiency, sometimes caused by a high potash feeding regime. A couple of teaspoons of Epsom salts (magnesium sulphate) per gallon of water will usually rectify the deficiency
Don’t be tempted to grow lettuces among bed-grown tomatoes; the fertiliser salt concentration will be too ‘rich’ for them and cause a high proportion of root rot.
There is still time to sow swedes and turnips, late maturing and over wintering brassicas and late leeks. Late maturing carrots such as Autumn King can also be sown. French, broad and runner beans, squash, sweet corn, and outdoor cucumbers can be sown directly into prepared beds outside
Early or Second-early varieties of peas can also be sown now for a late crop. The first early peas sown in the early spring will be flowering and setting pods. Pick while young, succulent and sweet. After harvest, cut down the haulms (stems), but leave the roots in the soil to release the nitrogen back into the soil from the nitrogen-fixing bacteria within the root nodules. The same applies for over wintered or early spring sown broad beans.
Keep sowing lettuce at fortnightly intervals. Harvest salad onions, salad leaves, beetroot and radishes as they mature.
When the tops of over wintered Japanese onions start to fall over, they can be dried off and harvested. Leave the bulbs to dry in a sunny spot outside, or in a airy shelter if rain threatens. This will allow the skins to harden, and the bulbs will store better.
Early potatoes may start to be ready for harvesting; often when the plants come into flower. Take care when digging them up to insert your fork some distance away and to lift the soil carefully. On later potatoes, ensure that they are adequately ‘earthed-up’ to prevent the greening of tubers near the surface. Ensure that potatoes do not go short of water from now on to ensure the maximum yield of potatoes later.
Early summer cabbages and cauliflowers planted last year, or in early spring, will also be ready for cutting this month. Some fast growing cabbage varieties will ‘split’ if left too long before harvest. Next year avoid a glut by using staggered sowings.
As the weather becomes hotter, leafy salad crops do better when grown in partially shady areas. This will help avoid bolting, particularly in lettuce. Hot dry weather can lead to tougher bitter tasting leaves, especially if insufficiently watered.
If not already done so at the end of May, climbing and dwarf French beans, runner beans and sweet corn may be sown outside in prepared ground. Seedlings already raised under cover should also be planted in the early part of the month.
Courgettes (marrows) and gourds, pumpkins and outdoor cucumbers can also be sown or planted. To encourage good and early fruit set try hand pollinating by brushing the male flowers (identifiable by lack of young fruit behind the flower) lightly into the female flowers.
Outdoor ridge cucumbers planted out this month benefit from soil that has been enriched with lots of organic matter to help retain water. Pinch out the tip of the plant when it has made about six pairs of leaves, to encourage side shoots and cucumber formation. Feed regularly with a potash-rich fertiliser (tomato feed) and keep supplied with adequate water.
Continue to support broad beans with stakes and string, as well as supporting peas with sticks or netting.
Asparagus spears can continue to be harvested this month, from mature crowns. Do not harvest spears from crowns less than 2-3 years old. After harvest and flowering, it is a good practice to feed them with a balanced fertiliser to build up the reserves in the crown for next year’s harvest. Asparagus is dioecious, meaning that it bears male and female flowers separately on separate crowns. Female plants can be weakened by bearing fruit (seeds), leading to reduced spear numbers and size the following season. All male hybrid varieties are available, both as seed or young crowns, and these will not suffer reduced vigour by bearing fruit. Where mixed female and male varieties are present to set fruit, self-sown seedlings may arise. These may not breed true to the parent varieties so discard them.
Continue to control weeds to prevent them competing for moisture and nutrients and harbouring pests and disease. Hoeing regularly between rows on hot dry days will make sure the weeds shrivel up and die without re-rooting. Weeds within rows are usually swamped by the crop plants, but if they get a hold and are likely to set seed, careful hand-weeding may be needed, though care should be taken to minimise any root disturbance to the crop plant. Hand-weeding is usually easier when the ground is moist after rain, or watering, as the weed roots are less likely to snap off and re-shoot.
Check gooseberries for mildew and gooseberry sawfly. The first berries will be ready for harvesting or thinning this month, though they will tend towards the sour side. The remaining berries can be left to build up in size and sweetness. Keep the custard powder supplies topped up, ready for ‘goosegog’ tarts and crumbles.
Still time to formative prune stone fruits such as plums, damsons etc. Check all fruit trees and bushes for signs of pest attack and take remedial action.
Check out fruit trees and bushes for how successful pollination has been, and how many immature fruits are developing. Poor pollination may have been as a result of late frosts, or too windy a position to allow bees, and other insects, to fly successfully. If the latter, consider erecting a windbreak before next spring.
If pollination has been very successful there will be large numbers of young fruit. Towards the end of the month the ‘June Drop’ will occur when the fruit trees will shed or abort the excess fruit it can’t cope with to bring to maturity. This is quite normal, and will extend into the middle of July. It is important that the trees receive sufficient water during this phase, and later as the remaining fruit swells. If the trees are still heavily laden after the ‘June Drop’, it may be necessary to carry out some fruit thinning by hand to give the remaining fruit chance to attain a decent size. Some experts recommend the removal of the ‘King fruit’, the larger fruit at the centre of each cluster, which is often slightly misshapen at the stalk end. Unless you intend to exhibit the fruit, this could be considered a bit ‘precious’, the fruit will still taste the same.
A light top-dressing on apples and pears with Calcium Nitrate or Nitro Chalk will help keep the calcium levels up to minimise ‘bitter pit’, especially if the soil tends to be more acid than the recommended pH 6.5 level.
Soft fruit bushes and strawberries should be netted, if not done already, to prevent bird access. If you can, cherry trees will also need netting, if they are not too large. Otherwise try bird scarers.
Strawberries that have now set fruit should be ‘strawed-down’, lifting the young fruiting stalks onto to the straw gently. Barley straw is favoured, if you can get it, as this is less ‘harsh’, both for the fruit and the ‘pickers’. Strawberries will start to throw out runners towards the end of the month. Leave them until harvesting has finished. Harvest by pinching the stalk behind the ripe fruit and allowing the strawberry to rest gently on the palm. Handling the fruit with the fingers will damage the thin ‘skin’ and leave slimy ‘fingerprints’. Unless required for immediate consumption, pick during the cool of the day, in the morning after dew has lifted, and chill the fruit (not freeze!) as soon as possible. This will prolong its shelf life.
Pests & diseases
Blossom end rot on tomatoes and peppers may start to be apparent as dark brown to black rot at the distal (flower) end of the fruit. This is not a disease, but the symptom of calcium deficiency that occurs when water supply is erratic. Regular sufficient watering and appropriate growing media should prevent too much damage. A handful of calcium nitrate (nitro chalk) per square metre of growing area, then watered in, will help, as long as irrigation is regular and not sporadic.
Asparagus beetles, which are black, red and yellow, and have creamy-black larvae, will be active now. Pick them off stems and foliage by hand (in other words, squash ‘em!)
Blackfly (a type of aphid) will attack the young tender top shoots of broad beans. Pinch out the top of broad beans once the lowest flowers have set. This will help prevent minimise any damage.
Flea Beetle will continue to chew small holes in young brassica seedlings and plants, particularly in hot dry conditions. Keep them well watered to help them continue to grow, despite the pest damage. This is normally sufficient to minimise losses without having to resort to a pesticide dust
Cover young brassica crops with nets to protect them from pigeons. Check for cabbage root fly damage and/ or club root disease. This will be apparent by a sudden wilting of the plant, even though the crop is well watered. Gently scrape the soil from around the lower stem and look out for tiny maggots chewing into the roots, These are cabbage root fly larvae. You can try squashing as many as you can to minimise further damage, followed by earthing up the stem to allow secondary roots to form. If damage is too severe rogue out the plant and destroy, along with the maggots. Next year use collars to minimise attack. Commercial growers have access to pesticides against this pest, but these are unavailable for use by the amateur grower.
In the absence of any maggots of the cabbage root fly, another possibility is that the stem has been chewed through by a chafer grub, or leatherjacket, but if this isn’t the case it is likely that the dreaded club-root disease is present. Remove the plant and roots from the ground and examine the roots. The typical ‘finger and toe’ swelling of the roots indicates club root. Destroy the plant by burning, and avoid planting brassicas in this area for the next twenty-odd years (just to be on the safe side!)
Keep carrot root fly off carrots and/or parsnips by covering them with a fine mesh like Enviromesh. make sure any corners are well tucked in or buried to prevent access. Remove any thinnings from the area immediately to avoid the ‘carrot smell’ acting as an attractant. Commercial growers have access to pesticides against this pest but these are unavailable for amateur use.
Celery leaf miner can attack both celery crops and parsnips. Cover the crops with mesh if this pest is prevalent in your area. A mild attack can be tackled by squashing the larvae within the leaf ‘mines’ by hand. A mild attack should not cause more than slight ‘cosmetic’ damage, but a severe attack will cause major leaf damage and a much reduced crop. Again there is no ‘amateur’ pesticide available.
Keep a watchful eye out for fungal diseases on both fruit and vegetable crops and spray with an approved fungicide where available. Pay particular attention to, and follow exactly the manufacturer’s instructions on the container. If you don’t, you are breaking the law! Observe the ‘harvest interval’, the minimum amount of time that must elapse between the last spraying and harvesting the crop. Look out for Potato Blight alerts on the message board and carry out preventative spraying of approved fungicides. Improving cultivation methods, by not planting too thickly or closely and ensuring a free air flow will help minimise problems. Most fungi prefer a still humid atmosphere, though powdery mildew will become more prevalent under dry conditions.
Keep an eye out for ‘rusts’ on garlic, leeks and other alliums. Orange coloured pustules of spore bearing bodies will become apparent on the stems and leaves. Spray with an appropriate fungicide.