My first botanical treat on arriving back in PA recently was to find one of my favorite American wild flowers blooming luxuriantly by our little stream. The cardinal flower, Lobelia cardinalis, is usually eaten off at the knees (or even the ankles) by the deer as it runs up to flower but this year they seem to have left it largely alone. There are fewer deer this year, I think, and fewer deer means more flowers – it’s that simple.

The plants are growing in partial shade both in the water (just a few inches deep) and on tussocks in the stream but nowhere drier. Their brilliant scarlet flowers really gleam in the shadows.

Back in June I posted about the red valerian, Centranthus ruber, growing over a wall in various colors just up the road from our house in Northamptonshire, England. Then Amy Stewart asked about the rarely seen Centranthus lecoqii on her blog and we exchanged comments about this unusual species.

Well, when I was England recently I came across Centranthus lecoqii at Bob Brown’s Cottage Garden Flowers nursery – and it turns out that he got it from Marina Christopher at Phoenix Perennial Plants. And here it is. A very pretty, more subtle, less punchy plant than red valerian and a lovely soft lilac shade.

I was in a nursery in New Jersey the other day, just browsing around,… imagine my shock. Echinacea ‘Twilight’ – the price tag said $27.99! (That’s about £14.) OK… the two-stem plant was in flower (though past its best) in a big pot… but that seems an extraordinary price even in an affluent NJ suburb. The same nursery was just taking delivery of a batch of Lythrum salicaria ‘The Rocket – that’s a pink flowered form of… purple loosestrife.

The day before I’d been at a much smaller nursery, Catskill Perennials, where their echinaceas, in slightly smaller pots, were priced at $11 (c£5.50). That’s more like it. And the only purple loosestrife in that part of the world is in the roadside ditches.

There’s no doubt that the very best delphiniums are those propagated by division or cuttings. But it’s impossible to produce them in the large numbers gardeners need by these methods and tissue culture, which works so well for so many perennials like heucheras, campanulas, coreopsis and so on, doesn’t yet work for delphiniums. I’m sure they’ll crack it eventually, but in the meantime the only way to raise delphiniums in the numbers that nurseries and gardeners really need is from seed.

One of the best was ‘Aurora Light Purple’ – lovely colour, good flower form and no off-types – but there’s one big problem with delphiniums from seed: they are very difficult to keep true to colour, superior spike quality and good garden performance. So the trial of seed-raised delphiniums under way at the RHS garden at Wisley is very useful. Even in this first year, it’s clear that some entries are much more uniform than others. There are forty-six in all, and they’ll be judged this year and again next year.

But even if the colour is uniform if the structure of the plant is poor, then it’s still not a good garden plant. ‘Clear Springs Lavender’, for example, produced a lot of lovely, well-formed spikes but the display was spoiled by the secondary spikes growing up around the main spike while it was still at its best. It may sound a like a small thing, but in the garden it makes a big difference.

The trial continues through next year, I’ll report the results when they’re in.

The most colourful trial at the RHS garden at Wisley this year is the trial of multiflora petunias. Well, let me re-phrase that: ...sometimes the most colourful trial...

The first time I looked at the trial was following an absolute deluge… and out of 202 entries to the trial only a very few were looking good – the low, spreading, ground-hugging types in the Opera Supreme and Shock Wave series. The rest were just battered by the rain and had not recovered – the very worst affected were probably those with white edges to the petals.

Two weeks later, the trial was transformed – a sparkling vision of colour - even though there’d been a shower the day before which had left the flowers of many entries spotted. The veined types, by the way, seemed to resist spotting most effectively. Again the Opera Supreme and Shock Wave series were outstanding.

Over the two visits these were the most colourful varieties, the most uniform, and came back after rain or resisted the rain most effectively; ‘Opera Supreme Purple’ stood out above them all for resisting the deluge and coming back well and for not spotting after the shower, other exceptional ones were: ‘Celebrity Pink’, ‘Celebrity Mid Blue’, ‘Hurrah Salmon’, ‘Hurrah Coral Fire’, ‘Frenzy Pink Morn’, ‘Frenzy Light Blue’, ‘Prime Time Pink’, ‘Prime Time Lavender’, ‘Horizon Bright Rose’, ‘Horizon Lavender’, ‘Baby Duck’, ‘Pink Lady’ plus, in the Opera Supreme Series, Pink Morn, Lilac Ice, and Blue, as well as ‘Shock Wave Pink Vein’ and ‘Shock Wave Purple’.

The summer still has a lot to throw at them – heat, as well as rain, I expect – but already this trial proves that there are some varieties that deal with the worst weather outstandingly well.

The annual Royal Horticultural Society trial of dahlias held at Wisley is always spectacular. It includes plenty of traditional large-flowered exhibition types but increasingly features small plants with smaller flowers - more suited to containers and small mixed borders.

This year there’s quite a range of short, dark-leaved dahlias on trial and one in particular stood out – ‘Happy Single First Love’. This is one of a series of single-flowered, dark-leaved dahlias from Holland, all of which looked excellent. But the unique colour of the flowers of ‘Happy Single First Love’, set against the rich foliage, made a knockout combination.

Footnote. While bending over to photograph these dahlias my phone slipped out of my pocket. I didn’t notice till later. I went back… but what are the chances of finding a black phone amongst all that dark foliage? And I wasn’t exactly sure where I’d lost it. In fact I looked in vain for so long that I was locked in the garden after closing and had to exit through the restaurant delivery bay! Next day, I borrowed my mother’s phone and went back.

I dialled my phone up and down the delphinium trial… amongst the monardas… finally I heard my phone ringing amongst the dahlias. And there it was, caught in the bushy growth of a dark-leaved Happy dahlia. Thank goodness they hadn’t had the irrigation on.

I’ve always been a bit suspicious of flower pouches. These are the green bags that you hang on a fence or wall and plant up with trailing plants through the holes. Like a vertical hanging basket – sort of.

But on this week’s first visit to the trial grounds and display garden at Thompson and Morgan, near Ipswich in the east of England, I have to say I was impressed. In the picture you can see the variety of plants that do well: petunias, verbenas, even lavenders, and the superb new trailing viola ‘Friolina’. T&M are trying all sorts of plants in Flower Pouches, and their trials and display gardens demonstrate how well so many do. And they'll fit into the tiniest garden.

The key to success is watering and feeding. For anyone with more than the occasional pot on the patio, installing watering where you just turn on the tap and the water drips into each and every pot – or each flower pouch – is essential. And it’s never allowing flower pouches to dry out that ensures they look so good.

You can buy flower pouches in the UK here

You can buy flower pouches in the US here