Peace Lilly
This is some advice I found online on how to make Peace Lillies (house plant) flower abundantly, I have tried this, and it really works.
David Denyer a plant expert explained that Peace Lilies require potassium to aid with their growth, so using a banana peel is a unique way to help with this.

To make some potassium-rich fertiliser, put some banana peel in a jar of water, and leave it to sit for at least a day or two – the longer the better! Once the soaking process is complete, Denyer recommended to “drain the water into a fresh jug and dispose of the banana peel”. Then, dilute the banana peel water with some fresh water and use this liquid to water your peace lily.
The gardening enthusiast advised that if banana water is used twice weekly, “it will help to keep the nutrients in the soil rich and promote growth”.
I just put banana peel around the peace lily in the pot and within10 days I had three flowers.
Deadheading
July is supposed to be one of the hottest months of the year, but this year who knows. Generally speaking summer is when we use our gardens the most and therefore deadheading plants will help the garden look attractive for longer.
Deadheading is the removal of flowers from plants when they have faded or died and is done to keep plants looking attractive and encourage re-flowering. It helps keep displays looking better for longer. Apart from appearance it also directs energy to give stronger growth and more flowers. It also prevents plants from self-seeding and as attractive as they are you may not want a garden full of plants such as valerian and erigeron.

Catmint, hardy geraniums and alchemilla may produce a second flush of flowers if cut back close to ground level after flowering. Oriental poppies can be cut back but normally will only produce fresh foliage.
There are some plants that do not require deadheading, and these include, fuchsias, rudbeckia, sunflowers, many viburnums, rambler roses, nigella and honesty.
General Maintenance
If it is warm/hot ensure you keep new plants well-watered, and hoe off weeds, as most perennial weeds are best dealt with in the summer when the weeds are in active growth.
Liquid feed plants in pots and keep well-watered in dry spells.
Ensure newly planted trees and shrubs do not dry out. They often need much more water than you think.
Mulching borders can help retain moisture and keep down the weeds – this will save a lot of work. A really thick layer of mulch (5-7.5cm / 2-3in all over) works best.
Pruning Shrubs
Prune June-flowering shrubs such as Philadelphus and Weigela after flowering. Prune this month to give the plant time to produce healthy new growth that will flower next spring.
Fast-growing hedges such as Leyland cypress should be clipped as necessary throughout the growing season.
My favourites
I sometimes find it overwhelming when visiting garden centres or going to flower shows, as you are faced with a riot of colour, and it is so easy to get caught up and buy plants that are not suitable for your garden. I have got better at this as I try not to buy plants unless I know where I am going to put them. Naturally, I weaken at some point and cannot help myself.
The ones below are favourites of mine and most will give interest and colour from June into November
Penstemons instant colour and flowers June to October. Perennial so will return each year.

Penstemon Grape Taffy
Salvias flower June to November. Large range of colours and they are a magnet for butterflies and bumble bees. There’s a great variety to choose from, including tender bedding salvias and hardy perennials that come back year after year. All of them thrive in full sun and most flower from mid-summer to autumn.

Salvia with Monarch butterfly
Heuchera These do well in light shade and the colours they come in are so varied. In summer, spikes of tiny flowers appear. Flowers June to August, but leaves are spectacular for many months.
Erysimum ‘Bowles’s Mauve’ This is a beautiful plant bearing masses of purple flowers on tall spires, for months on end. Grow in sun or partial shade. It’s a short-lived perennial. Flowers March through to November.

Erysimum ‘Bowles’s Mauve’
Gaura is a deciduous perennial, is adaptable and easy to grow. From May to November. They have small starry pink or white flowers from early summer right through to autumn. They tolerate partial shade.

Gauta lindeimeri