In June the garden is at its freshest. It’s time to sit back and enjoy long summer evenings surrounded by abundant flowers and lush foliage whilst surveying the results of all your work earlier in the year.
If you worked hard in May, you should already have crossed many of June’s jobs off your list!
Summer Bedding plants
If you haven’t got your bedding plants yet, do it quickly now. Hop over to our Bedding plants hub and get your containers and baskets planted up.
You may not think of yourself as a ‘traditional bedding’ type person – but ‘bedding’ isn’t all frilly petunias and blousy begonias. The range of bedding varieties is vast – there is something to suit all tastes and the exciting opportunity to come up with your own creative plant combinations.
When planting up summer containers, swap petunias for the more delicate calibrachoas, such as ‘Apricot Shades’ and combine them with other elegant trailing plants such as Verbena ‘Samira Pink Wing’. Then for an upright focal point try one of the new dazzling salvias such as Salvia ‘Pink Amistad’. Winner of third place in this year’s Chelsea Plant of the Year Award, ‘Pink Amistad’ is a cousin of the best-selling ‘Amistad’.
These salvias simply flower their socks off all summer. Salvia ‘Love and Wishes’ and ‘Royal Bumble’ are my other two favourites. Once it gets going, my Salvia ‘Royal Bumble’ is densely covered in bright scarlet flowers all summer into late autumn, even in a partially shaded position and in my mild Southern climate I have found that it will stand the winter in a sheltered position in a pot. For real wow factor, combine the intense colours of these salvias with the sculptural deep purple foliage of Aeonium ‘Tip Top’.
Instead of thinking of boring rows of ‘Summer bedding,’ treat these temporary plants as clever gap fillers. Nicotianas, rudbeckias and osteospermums are excellent candidates as they all blend easily with other perennials. Plant them out closely as they only have a few months growing time and be sure to water them well before and after planting.
Tender plants and shrubs
Wherever you live, it should be safe to put outside all your tender plants such as cannas, cymbidium and lilies. You can also bring out your citrus trees and enjoy their delicious scented flowers on the patio.
It’s too late to establish shrubs in borders now, best to wait until autumn, but you can introduce new containerised shrubs. In north-facing, lightly shaded areas of your patio, provide a backdrop of lush foliage and pale illuminating flowers with hydrangeas, fuchsias and acers. In sunny areas, choose long-flowering shrubs such as Hibiscus syriacus and French lavender (Lavandula stoechas).
Pests are really on the march now so be vigilant. Check lilies for lily beetles, watch out for vine weevil notches on the edges of leaves and aphids on the soft tips of stems.
Be responsible and protect our declining insect populations. Avoid the use of chemical pesticides and use formulas which work by physical means instead such as RHS Bug & Mildew Control. These contain vegetable oils, animal oils and soaps, collectively referred to as ‘surfactants’, which smother the insects rather than poisoning them. These need to be applied regularly but there is no build up of chemicals or harvest interval. These organic sprays also contain nutrients such as magnesium, iron and manganese which promote healthy plant growth.
Box, privet, and western red cedar (Thuja plicata) can be pruned now and usually will need pruning again in August/September. Don’t hard prune Thuja plicata back to old wood as it doesn’t recover well and will leave unsightly bald patches. Be sure to check for nesting birds before you start trimming your hedges.
Watering & water conservation
Keep watering all your new young plants, bearing in mind that trees and shrubs normally require two growing seasons before their root systems are fully established.
Our weather is becoming increasingly drier so do everything you can to conserve water.
- Avoid bare ground and use ground cover plants to cover it. Ground cover doesn’t need to be drab. Recently featured on the BBC’s ‘RHS Chelsea Flower Show’, Geranium ‘Intense’ is a stunning new geranium with the most intense, deep magenta flowers on a very low plant – an unusual combination for hardy geraniums. Geranium ‘Intense’ will flower happily in partial shade and its semi-evergreen foliage continues to provide ground cover throughout the season as well as gorgeous red tinted leaves in the autumn.
- If you find that your perennials are suffering in dry weather get planning and make a list of more drought tolerant plants to introduce next year.
- Continue to apply mulches wherever you have bare soil on borders. Cover pots with a layer of grit.
- Invest in water butts and drip irrigation systems. The more water butts the better. Your plants will be much happier with rainwater which has a lower pH than tap water and none of the chemical residues. Acid loving containerised plants such as rhododendrons can become starved of nutrients when constantly watered with hard tap water.
- Deadheading makes a huge difference to the length of flowering so keep at it. Use secateurs to cut back to a strong pair of buds or shears to trim over mound-forming plants such as geraniums after they have finished flowering – you may get a second flush. Constantly pinch out the spent flowers of summer bedding and pick sweet peas every day before they have the chance to form any pods.
- The flower spikes of delphiniums, lupins and foxgloves should be cut right down. You may get more flowers but even if you don’t this cutting down will benefit the longevity of the plant.
Rhododendrons and Camellias
- Remove the fading flowers from rhododendrons and camellias taking care not to damage the new leaf buds which are developing just behind the faded flowers – pinch them out between finger and thumb.
Weeds have put on a surge of growth and are now competing with your treasured ornamentals. It’s important to keep on top of them and essential to pull them out before they self-seed. However, remember that although this is a priority job it isn’t an urgent one. You have a longer window of opportunity to do this task so don’t prioritise weeding over and above jobs which are more time critical such as getting supports in to rescue plants on the edge of collapse or planting bedding.
Don’t be so ruthless with your weeding that you obliterate the possibility of self-sown seedlings. It is really worth introducing some hardy annuals and biennials into your garden (see propagation) and allowing them to pop up by themselves each year. Learn to recognise the seedlings. They will self-select their preferred locations, colonising awkward gaps, crevices and path edges where it is difficult to establish plants, and dotting about to create a relaxed rhythm and feeling of maturity to the garden.
Whatever nature gives you, use it! Composting isn’t just for vegetable growers and allotments – it should be a cornerstone of your gardening practice. Composting not only provides a free, nutrient-rich soil improver and mulch but avoids green waste going to landfill. Traditional wooden compost bins are a cheap method, although require a lot of space. For small gardens, consider investing in a Hotbin Composter. It will compost waste within 30-90 days, can take cooked food waste and requires no turning.
- Roses are at their peak and flowering prolifically. Keep dead-heading repeat flowering varieties, using sharp secateurs to cut back to the first leaf behind the flower. If you’re brave you can simply snap off the flowers at their natural breakage point but make sure you wear gloves.
- Keep an eye out for suckers produced below the grafting point – they are usually lighter in colour with green stems and a different number of leaflets. Rather than cutting it off, dig down to expose its origin and pull the sucker off.
- Climbing roses, and especially ramblers, produce long and lethal whippy shoots at this time of the year which can catch you unawares when walking past. Keep them tied in or remove misplaced ones.
- Continue staking your plants as strong winds and rains at this time of the year can quickly flatten them. If you want to reduce the staking needs of your more boisterous perennials it might be time to try the Chelsea Chop (see below).
- You have a couple more weeks to have a go at the Chelsea Chop, although don’t try it out on perennials which have already produced flower buds – you are too late.
- This pruning technique will produce plants with shorter, self-supporting stems and more (but usually smaller) flowers. Not all perennials will respond to this treatment but those which do include: Asters, Echinacea (coneflower), Helianthus x laetiflorus (perennial sunflower), Hylotelephium (Sedum), Monarda (Bergamot), Nepeta (Catmint), Phlox and Rudbeckia. The results can vary depending on the species and your microclimate – if you’re nervous just experiment with chopping down a portion of your plant and judge by the results.
- Annuals: Early June is your last chance to direct sow fast-growing hardy annuals such as Clarkia, Godetia, Candytuft, Calendula and nasturtium. Hardy annuals sown earlier should now be rigorously thinned out.
- Biennials: As last month, sow biennials now into open ground or small trays/pots ready for planting out in the autumn. Try Lunaria annua, Canterbury bells, foxgloves, wall flowers and forget me nots.
- Perennials: Sow perennials such as aquilegia, lupins, delphiniums and hollyhocks.
- Sow winter and early spring flowers such as pansies and polyanthus.
- Continue to take softwood cuttings of perennials and shrubs. Pull off the non-flowering stems of pinks (Dianthus) to make cuttings about 5-7.5cm (2-3in) long, removing the leaves from the bottom third. Put them in a gritty compost and they should root within 3-4 weeks.
- If you are aiming for a neat, tight sward, continue to mow at least once but preferably twice a week whilst reducing the height of cut in prolonged dry spells. Edge the beds every week to keep them tidy and prevent grass from growing into them. If the lawn is looking tired, apply a summer feed, preferably using an organic formula such as Viano Lawn Boost.
- Keep watering any new turf which you laid earlier in the year.
- Floating pond plants are now in full growth and available to buy. The water has warmed up and it’s time to introduce new specimens.
- Continue to remove duck weed by gently raking it off.
Cut down faded foliage of earlier flowering spring bulbs such as daffodils, allowing them 6 weeks after flowering. Also lift and divide any congested bulbs.
Once oriental poppies have finished flowering the foliage dies back and they look tatty. Cut them right back to the ground, not just the flower stems but all the foliage too. Fresh new foliage will appear and sometimes a second round of smaller flowers.
Euphorbias and early perennials
- Tidy up all your spring flowering perennials, removing tired, mildewed foliage. If you didn’t do it last month, this is the time to lift and divide any early spring flowerers such as Brunnera, Pulmonaria and primulas.
- All evergreen euphorbias such as Euphorbia amygdaloides var. robbiae, Euphorbia characias and Euphorbia x martini should be pruned now. Once the yellow bracts have faded, cut all the flowered stems right back, leaving young new stems to flower next year. Use gloves as the milky sap is a skin and eye irritant. Be especially careful with large Euphorbia characias plants as you will need to bend down into the plant and will get covered in dripping sap – long sleeves are essential.
- Late spring/early summer flowering shrubs such as Deutzia, Kolkwitzia, Philadelphus and Weigela can be pruned after flowering. Remove dead or damaged growth and cut out one in three of the oldest stems, being careful as you remove them to avoid damaging the remaining stems.
- Old lilacs can become leggy over time but respond very well to renovation pruning, producing plenty of new shoots when pruned back to a low base. However, you may need to wait until the second year until they flower again.
- Treat your houseplants to a summer holiday! Placing your houseplants outdoors for the summer has numerous benefits. Wind and rain remove dust from the leaves and plants will enjoy higher light and humidity levels. When taking them outdoors, acclimatise them slowly to outdoor conditions and light levels, placing them in a shady, sheltered position. Houseplants can quickly scorch when placed in bright outdoor light. Leave hairy plants such as African violets indoors, as they don’t appreciate water on their leaves.
- If any houseplants are becoming severely pot bound with roots poking through the holes of their pot, then you should pot them up now whilst they are in active growth.