Jobs to do in the garden in June: from watering to deadheading

There’s something particularly joyous about a June garden. Annuals and perennials are bursting with colour and interest and, for many gardeners, this is the best month for blooms.

“June is a wonderful time in the garden,” says horticulturist Sarah Raven. “Flowers are starting to appear in abundance and there’s plenty to harvest in the kitchen garden. Keep on top of supporting your plants and keep an eye out for cold nights at this time of year, as some plants will still need protection.”

It’s also a time to prune, mow and weed, as natural growth starts to run riot. And don’t forget to water. Watering in the hotter months is always best done in the morning or evening to avoid scorching plants in the heat of the day. Keep tubs and planting containers well-hydrated too, even in rainy weather, as much of the water runs from the leaves over the side.

So, grab your gardening gear, and make a note of these jobs to do in the garden in June…

1. Sow poppies

Papaver – otherwise known as poppies – are a must in the garden for their charm, colour and fleeting qualities.

They are so simple to cultivate too, as they prefer to be sown directly into ground soil rather than into a seed tray. They hate their roots being disturbed.

“Follow the rule of the four Ts to succeed with direct sowing,” says Raven.

"Sow into a fine Tilth (finely tilled soil), at the right Time (when the soil is warm and moist), sowing as Thinly as you can, and then Thin the seedlings to leave them spaced 25-30cm [10-12in] apart.”

If you sow direct now, many varieties will flower within eight weeks.

The oranges are always a hit, such as Papaver rupifragum 'Orange Feathers' and Eschscholzia californica ‘Fire Bush’. They work perfectly with lavenders and, what’s more, they’ll self-seed freely for more plants next year.  

2. Support stems

Use metal stakes, bamboo sticks or foraged branches

Many of our favourite British border plants need support to help them to perform best.

“The key is to do this early on,” advises RHS Rosemoor’s curator Jonathan Webster. “This means that they grow through and around the frame you are using, giving them a more natural look.”

Taller, more fragile, herbaceous plants, such as delphiniums and peonies, are best suited to metal link stakes, which come in various heights and link together to strengthen the support they offer. Often green in colour, these blend in and do not detract from the glorious blooms above.

“Flower rings are also great for supporting plants such as freesias and chrysanths,” says Raven. “Annuals like sweet peas,” adds Webster, “like to climb on branches of hazel or silver birch woven into artistic structures. This also adds another element to the garden in the form of art.”

3. Water well in the greenhouse

Get the temperature just right

In the greenhouse, keep your crops well-watered with tepid water. It’s best to use tap water for seedlings to avoid any water-borne contamination from the water butt. “Pay particular attention to crops in growing bags,” says Tom Barry, CEO of greenhouse specialist Hartley Botanic.“The relatively small plant-to-compost ratio means they can dry out rapidly in hot weather.”

Remember that erratic watering can cause calcium deficiency, resulting in ‘blossom end rot’ on tomatoes and peppers. This is when a browny black circular patch appears at the end of the fruit furthest away from the stem. In the growing season, this is best avoided by keeping the compost consistently moist, watering one to two times a day depending on the temperature.

4. Cut back for a second flush of flowers

Keep on top of the cutting back and tidying and you’ll be rewarded with a tidy space and even more flowers.

“Huge-flowered oriental poppies, such as the beautiful, dusky purple ‘Patty’s Plum’, have finished flowering,” says Raven. “Cut everything back to ground level, leaving no foliage standing. Feed, mulch, give them a good amount of water, and allow the new foliage to naturally grow back.”

“Cut back delphiniums right to the ground, including the leaves as well and old flower spikes,” she adds. “If you do this now, almost all plants will give you a second flush of flowers in August and September.”

5. Love your lawn

To mow or not to mow…

Lawns are important, as they provide space for us to relax. Lawns and the plants that surround them enhance each other, and the green tones create a tranquil atmosphere. “Mow and edge your lawn,” advises Raven. “Even if you don’t have time for any other jobs outside, it will make your garden look much better.”

“If it is not too hot and dry, your grass will need cutting weekly if you want to keep it looking sharp,” adds Webster. “If a dry spell is on the horizon, raise the height of the cut on your mower, which helps to preserve a bit of moisture and keep your lawn greener for longer.”

We all know that creating habitats for wildlife is important, so continue the No Mow May ethos and, where you can, leave some of your grass uncut. Let it grow and you will often be surprised what wildflowers pop up and flower. 

6. Deadhead roses

It's crucial for more flowers

Deadhead roses as often as you can. “Snip off their browning heads to a bud or leaf below to help promote the formation of axillary buds,” says Raven. “Then more flowers will follow.”

Rambling and climbing roses will be growing rapidly so tie them in regularly to keep them upright.

From June to September, established roses need to be watered once a week. “As your rose starts blooming, take note if your flowers are wilting,” suggests Paul Constantine of David Austin Roses. “This will happen in extreme heat but is a reliable sign that your roses need more water.” Newly planted roses will need to be watered every other day.

7. Prune spring-flowering shrubs

Remove the three Ds first

Jobs to do in the garden in June include pruning spring-flowering shrubs, such as forsythia, ribes (the flowering currant) and philadelphus (commonly called the mock orange).

“These are all deciduous plants, meaning the leaves fall off in winter; they flower on the bare twigs of the new wood, which will grow over the summer,” says Webster. “The great benefit of pruning these now is so you can see the flowers rather than a dense mass of colour.”

“The guide is to remove the three Ds first – dead, diseased and dying wood. Then prune out around a third of the oldest wood to the ground, balancing the plants’ framework.”

8. Don’t let weeds take over

Plant tightly and use mulch to keep them at bay

Keeping on top of the weeds in our garden is a constant challenge. “When we have a dry spell and it is a sunny day, using a hoe will keep weed numbers down,” says Webster. Leave the weeds to shrivel in the sun.

As gardeners, we can do many things to reduce weeds. “Simply planting tightly so there is no open ground helps and, of course, applying mulch or compost, which will also keep moisture in the soil too,” he adds.

Watch out for ‘free’ plants that have self-seeded. In many cases you can leave these, but editing may be needed.

9. Enjoy cut-and-come-again salads

Only harvest what you need

Summer is the time for home-grown salads. Known as 'cut and come again', they are just right for pots or veg patches.

Many things can be grown this way so you can enjoy the fresh young leaves of lettuce, mustard, parsley, rocket and spinach. “Harvest using scissors when they are big enough and only take as much as you need, as they will wilt quickly. So save what you don’t need until the next day!” says Webster. Leaves can be harvested for a prolonged period, as you are stopping them maturing and more new growth occurs; for a continuous crop keep sowing in different batches throughout the season.

As they are so tasty, other things will want to eat them before you,” says Webster. “So keep an eye on them, as slugs and snails may beat you to them. You can try various methods to protect them. Pots off the ground works, barriers with rough surfaces, or biological control, with creatures called nematodes that you dilute in water and simply apply whilst watering.”

10. Fill gaps with bedding plants

There are so many jobs to do in the garden in June to keep on top of a flourishing green space that’ll keep you busy, make you smile and ensure that your outdoor areas continue to bloom through the summer.

And if things aren’t looking perfect, take note of a little cheat from Raven: “Fill any gaps in your borders with bedding plants, such as salvia, begonias, and one of my favourites – pelargoniums.”