PIB Gardening Hub - Jobs for August by David Bassil

Short lived shrubs such as Salvia and Penstemon may not over-winter. It is advisable to take cuttings now to ensure new plants for planting out in the Spring. 

Now is a good time to plant Colchicum (Autumn Crocus) and Lilium Candidum which should now be available in your favourite garden centre. 

Rambler Roses should be thinned at this time of year by removing about one in three of the shoots. Make sure the remaining shoots are tied in to their supports. . 

Lavender plants should be trimmed as soon as they have finished flowering by removing the dead flower heads and about 1 inch of growth below the flower stem, It is too late now to cut back Lavenders to rejuvenate them if they have been allowed to become leggy and woody, wait until next Spring.

Keep plants well watered in containers and feed on a regular basis using a fertilizer containing a high Potash level. Tomato feed will do this job for you - never at this time of year use a fertilizer with a high nitrogen content. You can check this out on the packaging - look for the N P K analysis, the K should always at this time be the highest and the N the lowest figure. 

Remember also to keep plants dead headed to keep the display going for as long as possible.

Fruit  - Summer fruiting Raspberry canes should be cut away as soon as the last fruits have been picked and then tie in the new growth to support them.

If you want to make a new Strawberry bed, now is a good time to buy new stock and plant immediately into a very well prepared weed free bed.  Never plant runners off your existing bed as these will already be affected with a Strawberry virus disease and also do not be tempted to plant runners given to you by a friend as the same result will be inevitable.

Vegetables  - Harvest Onions as soon as the foliage collapses and dry off thoroughly before storing away for winter use.  Parsley can be sown now to make a fresh supply of young leaves through to the spring.  

Basil can also be sown now for winter use but this must be grown on in a protected environment such as the kitchen windowsill.  

Pumpkins and Squashes should be raised off the soil level to prevent rotting.

Ponds - Oxygenating weed in ponds can become very overgrown at this time of year, remove by pulling out of the pond until about one quarter is left.  This will quickly grow and establish itself well before the onset of winter.  Also remove any blanket weed by using a stick and twisting it in the water to wrap this very invasive weed around it. 

Hedges - This is the last chance to cut conifer hedges to avoid die back, never do it later than the end of August.  Other hedges such as Laurel and Privet should not be cut after the end of July.

Divide and replant bearded Irises now if the clumps have become overgrown. Only replant the youngest pieces and reduce the leaves by about half their length to lessen transpiration while they are re-establishing themselves. Be sure to water well until establishment has taken place. 

Dead-head Roses as the shoots finish flowering to enable new growth to appear for a later crop of flowers. I have always found however that the best results are obtained if the shoot is pruned to just above a leaf about a third to a half below the old flower head.

Now is an ideal time to propagate Clematis by taking internodal cuttings. Cut the stem of a piece of current season’s growth discarding the top most part of the shoot where it is still too soft. Make cuttings by cutting halfway between the leaves (internode). Rooting powder is beneficial and insert several cuttings around the edge of a small pot containing multi-purpose compost. Water in and cover with a clear polythene bag. Fold the excess polythene under the pot to make a partial seal and leave in the shade until rooting takes place.

Continue to sow winter bedding plants such as Brompton Stocks and Sweet William for next year’s display. 

Continue to feed plants growing in containers with a balanced liquid feed such as Maxicrop or Miracle grow.

Plants such as Dahlias, Chrysanthemums, Cannas and herbaceous plants should also be fed but use a powder or granular fertilizer such at Vitaz Q4 or Growmore for this purpose.

 Sow Spring Cabbage now for use next Spring, also Chard and perennial Spinach.

 Water developing crops such as Courgettes well to keep them growing and the production of a larger crop.  

Now that the “June Drop” is finished, any Apple fruits which remain in clusters can be thinned to give bigger and better quality fruit. The trees should also be given an extra supply of water at this time to help swell the fruits. 

If you have suffered with Bitter Pit on your apples in the past, a spray with Calcium Nitrate now can prevent this happening. The tree should be sprayed by wetting the leaves and fruit in late evening when weather conditions allow.

GENERAL

 Compost heaps should ideally be turned from time to time to introduce more Oxygen to help in the decomposition. Add extra water if the heap is dry and add a nitrogen fertilizer such as Sulphate of Ammonia to quicken the rotting process. 

If you have to prune your ornamental Cherry trees for any reason, now is the time to do it with reasonable safety for the tree. At any other time there will be a serious risk of developing one of the many diseases this type of tree is very susceptible to.

Quick growing annual flowers such as Cosmos and Marigolds can still be sown this month if a space becomes available and will still give a very good display in late summer and into the Autumn months.

Autumn bedding plants such as Wallflowers, Bellis and Violas can be sown now and grown on for planting out into their flowering positions in October or November. Once Oriental Poppies have finished flowering, cut back all the growth to  ground level and a fresh amount of growth will quickly appear with flowers later on in the season.

If you have clumps of Daffodils which have not flowered well this Spring, now is the time to dig the clump up before all the foliage dies down and select the biggest bulbs. Replant them, spacing each one out about 10cms apart. The smallest bulbs, which will not flower should be discarded or replanted in a nursery bed to grow on for a year or two.

 A sowing of Carrots now, using a variety such as Chantenay, will provide young carrots for winter harvesting.

Strawberries should be netted now to avoid the ravages of birds taking all the ripening

fruit. Straw placed around the plants will prevent rain splash and help ripening.

Potatoes should not be allowed to dry out at this time otherwise they will become

more severely affected with scab.

Feed Tomatoes regularly with a high potash fertilizer such as Tomorite and make sure

that watering is done whenever it is needed, otherwise Blossom End Rot will become a

nuisance, together with splitting of the fruits.

 If you have a problem with bindweed, ground elder and other invasive weeds, paint

some of the leaves with Roundup. This is a translocated weedkiller and will be taken

in through the leaf and down to the roots, killing the plant in this way.

Mow lawns on a regular basis about once a week but avoid cutting too low, especially

in dry spells. Also make sure any newly sown lawns or turfed areas are kept well

watered.

In the greenhouse, damp down the floors to create a humid atmosphere and reduce the

temperature. This also has the effect of reducing the likelihood of contracting the

dreaded Red Spider mite.

A lot of variegated shrubs will at this time of year produce green shoots. These should be removed as soon as possible as they will cause the shrub to revert.

 Plant up containers with summer bedding plants using a good quality compost. One I would recommend is a Clover multi-purpose compost. Remember to add Osmocote controlled release fertilizer to the bottom third of the compost in the container and add a sprinkling of moisture retention gel to reduce the amount of watering needed.

Keep a careful watch for the Red Lily Beetle adults and larvae on your Lilies and remove with your fingers or spray with Resolva Bug Killer.

All indoor plants should be watered and fed on a regular basis at this time of year and a misting over with clean water (preferably rain water) will keep the plants looking healthy.

 Potatoes should be earthed up this month to get a better crop as the potato is a stem rooting plant and this will also reduce the amount of green tubers produced when they reach the light.

Continue to pick Rhubarb on a regular basis to keep the production of young leaves going. If a flower spike is produced remove this with a sharp knife right to the base of the plant.

Continue to make successional sowings of Carrots, Beetroot, Radishes and Lettuce direct into the open ground.

Runner Beans and French Beans can also be successfully sown direct into the open ground now, but remember to sow the seeds on their edge for best results.

 Thoroughly water newly planted Trees and Shrubs including fruit to allow the plants to establish well. This will need to be continued throughout this growing season

Remove the flower heads on Rhododendrons now that they are finished but take care not to damage the buds just below the old flower head.

If you have a Camellia which needs pruning, now is an ideal time to do it as regrowth at this time of year is assured.

Spring flowering shrubs such as Forsythia, Philadelphus and Weigelia should be pruned now as the young growth produced will then gave a splendid display of flowers next Spring.

 Apply slug/snail killer to your plants to protect them from damage or use some of the alternatives if you would prefer to do so, but some sort of protection must be put in place. 

Use insect mesh to control the ravages of Carrot fly to your Carrots and Parsnips.

Greenhouse - Ventilate greenhouses to reduce overheating and shade with netting or Summer Cloud to prevent burning of the plants inside.

Start a regular feeding programme now for all your houseplants after their rest through the winter and early spring. 

Also complete the repotting or top dressing of your plants as soon as possible. 

Always use the same type of compost the plant is growing in to repot or top dress. 

Soil based compost – keep to the John Innes range, suggest No. 2 or No. 3 but if soil-less compost was used originally keep to one of the same type. Never try to change from one to another. 

Spray new foliage of Roses now with one of the very good specialist rose sprays available at any garden centre. This will protect against Mildew and Blackspot. Sprays should be repeated every 10 – 14 days from now until the end of July if possible. It is also a good idea to alternate sprays with different products to reduce the chemical resistance.

Plant summer flowering bulbs such as Gladioli, Eucomis, Lilies, etc now for colour later in the year.

Hardy Annuals can now be safely sown direct into carefully prepared positions in the garden where they are to flower. 

 It is a good time to prune the stems of Penstemon back to about 6 inches (15cms) to create a less straggly plant and with many more flower stems. 

At this time of year if you have a greenhouse it will be bursting at the seams with all the new plants being brought on for planting out later. 

Prick out young seedlings before they get too large and keep the greenhouse ventilated as much as possible to lessen the chances of fungus diseases taking hold. 

Now is also a good time to undertake any major pruning work on evergreens such as Photinia, Griselinia and Prunus Lusitanica as they will readily make new growth at the time of year. 

Continue to sow seeds of Chard, Coriander, Parsley, Beetroot, Carrots in modules in a cold greenhouse for planting out later. 

Brassicas can be sown direct into seed beds for planting out in June.

Weeds are now beginning to germinate freely so keep the hoe moving at every opportunity when conditions allow.

 Seed potatoes are best obtained now and set up for chitting (to produce their shoots) by placing in egg boxes or trays in a light frost free place. 

If you have a greenhouse and can keep it warm enough, especially at night, you can make the first sowings of vegetables such as Cabbage, Leeks and Onions in small trays and prick out into larger containers when they have germinated. Alternatively seed can be sown into small pots or cell trays directly. I would suggest sowing two or three seeds per cell and thinning out to the strongest one after germination has taken place. 

The first sowing of Tomatoes can also be made this month but the warmth is of even greater importance with this subject. As with flowers obtain all the seeds you need for the season.

 Autumn fruiting Raspberry canes should be pruned down to almost ground level now ready to induce the new growth to fruit for you this coming autumn. 

Tidy up Strawberry plants by removing all dead or decaying leaves and any unwanted runners. 

 Prune late flowering Clematis down to about 6 inches from ground level to a pair of healthy buds. 

If you have overcrowded clumps of Snowdrops, now is the right time to lift, divide and replant in the green stage. It is important to plant back at the same depth that they were in before moving. 

Fuchsias which have been overwintering in the greenhouse can be pruned and re-potted now but do not do both jobs at the same time, better to prune first and then repot two weeks later. When pruning do not be frightened to prune hard back and when repotting to move all the old compost from around the roots and repot back into a smaller pot, this will enable some room to pot on again into the final larger pot as the season progresses. 

If you grow Bougainvillea and Plumbago in your conservatory, now is a good time to prune them by cutting back all growth to two buds from the main framework. This will produce many more shoots to flower later in the season. 

If you have not already done so, purchase now all the flower seeds you wish to grow this year. Also obtain your summer flowering bulbs and corms before supplies run out.