As much as I love the freshness of a June garden, September is my favorite month. Some visitors seem surprised that we “still” have so much color but I can’t imagine it any other way. The gentle light and the beautiful cool blue days demand that we be outside reveling in exuberant color. We definitely plan for this time of year (in truth, for the whole summer into fall season) to be stupendous but it doesn’t take much – a few annuals like zinnias, ageratum, and alyssum; and a handful of tender perennials like dahlias, salvias, angelonia, and plectranthus and you’re golden. Or the garden is in any case, especially in the slanted light of September. Even with roses, delphinium, asters, and euphorbia (re)blooming in the Rose Garden, it wouldn’t be nearly as spectacular without the annuals and tender perennials giving them a boost. I know a lot of gardeners choose not to buy plants that won’t survive the winter outside but I think those plants are worth every penny (and seed annuals like zinnias really do just cost pennies) because they’re the ones that carry the garden so effortlessly past its usual early summer peak well into the prettiest months of all.

And of course, some of them can survive the winter and carry whatever we spent on them into the next season too (and the next after that and the next…) We’ve started taking cuttings of some of our favorites like porterweed (Stachytarpheta mutabilis), cigar plant (Cuphea spp.) and heliotrope. We’re lucky to have the greenhouse for overwintering them but sunny windowsills would work too.

Is your garden as colorful as you’d like it to be this month? Do you use annuals and tender perennials too or do rely on late-blooming hardy perennials and shrubs? For a look at a whole world of colorful September blooms, check out May Dreams Gardens Garden Bloggers Bloom Day (September 15).

I am as fickle as any gardener. I’ll pick a new favorite color, fragrance, leaf, flower, and plant habit every other week (or day) and reserve the right to change my mind over the slightest disappointment. That said, the hyssops, which have been blooming since June, are vertically eye-catching, and smell like candy, have managed to stay at the top of my favorites list for months now. I also think they deserve the  “Most Attractive Plant” award in the 2012 Blithewold yearbook superlatives.

Agastache, which is pronounced ah-GAH-stah-kee or aga-STAK-ee depending on who says it (tomato, tomahto), is Greek for very much (agan) spike (stachys) according to Allen J. Coombes’ The Hamlyn Guide to Plant Names. (He pronounces it the first way.) Very much spike is right. And probably because their native habitat is sharply drained hillsides they’re fairly sturdy, unfussy, and drought tolerant. They are also hardier than I ever thought. Around here anyway, wet winters and poor drainage are more likely to do them in than cold temperatures.

We are growing North American native anise hyssop (A. foeniculum, zone 4-11) because it seeds itself all over the Display Garden. Its spikes start out a lovely dusty blue and deepen over the season and are more slender than its hybrid child ‘Blue Fortune’ (zone 6-9; crossed with Korean A. rugosa). That’s the one we’re growing in the Rose Garden this year and the bees can’t get enough of it. My personal favorite, planted in the Display Garden and North, is ‘Black Adder’ (zone 6-9). The deep indigo bracts are spectacular especially now that every plant is also decorated with its own klatch of a half-dozen or more American Lady butterflies. (At least I think that’s what they are.) All 3 are standing a good 4-5′ tall now and need propping – particularly top-heavy ‘Blue Fortune’ even though we lopped them back by half in late May or early June. In my own garden, I grew ‘Golden Jubilee’ (zone 5-9), which has brilliant chartreuse foliage through mid-summer and pale grey-blue spikes. The best thing about that plant is that its seedlings have already started to pop up. The more the merrier. We have no intention of deadheading any of these because we’re looking forward to their structure over the winter, but we have used some stems in flower arrangements.

I always though that the cultivars of hummingbird mint like ‘Heatwave’, ‘Acapulco Orange’, and ‘Summer Glow’ were tender but they’re at least as hardy as ‘Black Adder’ and ‘Blue Fortune’. Both ‘Heatwave’ (zone 5-10) and A. mexicana ‘Acapulco Orange’ (zone 5-9) came back for us this year but last winter was unusually dry and mild so it probably wasn’t a good test. We have our fingers crossed for ‘Summer Glow’ (zone 6-9) in the North Garden, which in its first year isn’t as outstanding as the others but certainly could be the prettiest of all with one more season’s growth. We’ll probably take cuttings and overwinter a stock plant in the greenhouse just in case it doesn’t make it outside. The slightly contrasting bracts on ‘Acapulco Orange’ and ‘Summer Glow’ make those my faves over ‘Heatwave’ (plus they’re orange) but the hummingbirds probably have no preference at all.

Are you as in love with agastache as I am? Which ones do you grow?

I used to really enjoy the challenge of staking top-heavy plants in such a way that their crutches were as invisible as possible but this year, maybe because the ground is dry enough to make shoving bamboo poles in nearly impossible, I’m kind of over it. I’ve discovered (or maybe rediscovered) an appreciation for plants that still look good when they slouch like lazy teenagers. Some of them, like yarrow have a way of leaning on their neighbors that, from some angles (perhaps not this one – below), doesn’t look like they’re a great crushing weight. I’m also kind of in love with plants that don’t have what I think it was Anna Pavord called “weak ankles.” Agastache ‘Black Adder’ and Stachys officinalis ‘Hummelo’ might be my favorite regimental soldiers ever. And if I can get away with not staking — by cutting something back instead, I will. Any Gaura lindheimeri or nicotiana that flops in the way of the mower is getting offed. No more propping.

We missed our chance to put peony hoops around the Veronica longifolia in the North Garden so each clump splayed open and leaned like drunks all over the back and middle row. Usually we carefully deadhead that one to prolong its lovely blue spikiness but I’ve taken to whacking most of the stems back to a foot or two in hopes that it will shape up for a sturdier show later. Perhaps next year we’ll add it to the list of plants that need to be lopped in late-spring early summer. I’m all for a slightly later bloom especially if the Coreopsis x ‘Full Moon’ never looked like this again. We did remember to cut back Rudbeckia ‘Henry Eilers’ and Boltonia ‘Nally’s Lime Dot’ and although they’re both already about 5′ tall, at least it doesn’t look like they’re about to fall over. Last year I constructed a web of stakes for the great burnet (Sanguisorba tenuifolia) and this year we smartly moved it back to lean against a fence again, this time in the Cutting Garden.

So that just leaves the biggies that can’t be encouraged to branch in early summer or cut back now without tremendous sacrifice. I don’t mind if the cardoon lean a little bit but they could fall like trees in a gale. Dahlias too are so brittle that if they flop, they’re down for good, like it or lump it. Sometimes I don’t mind if they fall over because their flowers always manage to face forward but when we’ve planned for their bright shiny faces to show up in the back of a border, they’ve got to stand up straight and that means tying them up to a stake long before the wind blows. And we’re still using concrete reinforcing mesh in the Cutting Garden to hold up zinnias and amaranth and anything else that might topple under its own weight. We lay the grids down on the beds before planting, using the openings as planting guides, and then raise the grids up to provide support as the plants grow. (We really should raise them up early to let the plants grow through them but — call me crazy — I don’t like it when the garden looks like it’s wearing its foundation garments on the outside.)

How and what do you stake – and what do you do to avoid staking?

Despite knowing that pinching new growth makes plants branch into full and sturdy clumps that promise extra flowers, it can be one of the hardest things to do. Somehow it goes against the grain to nip healthy new growth and I just can’t do it sometimes. But then I always wish I had. The nepeta at my house grew so fast I missed my chance to pinch them before the flowers budded and now they’re splayed open and not-so-very pretty even though they’re blooming away. If only I had pinched them back in … April. Or if not in April, then a couple of weeks ago when I realized they were about to bloom. It would have been better to set the bloom timing back a bit for the sake of sturdier, bushier growth. Mental note for mental toughness next year.

Last year our Agastache ‘Black Adder’ and ‘Blue Fortune’ were tall and a little rangy so we determined to remember to pinch them this year. They should end up being a little shorter, the blooms might not be quite as large possibly, but the plant will look much better in the garden and there will be even more flowers for the bees.

We also pinched Aster ‘Lady in Black’, which we bought as spindly single-stemmed plugs. Cutting off the apical meristem, the tip of a new shoot, will send energy into the side shoots and make the plant branch. It feels barbaric to lop off their heads but they almost instantly respond – within a few days anyhow – by starting to branch out from every axil. I hate to think how weak and unattractive the plants might be if we didn’t decapitate them.

And the consolation prize for following through with this necessary but weirdly difficult task is that the pinched tips of annuals and perennials make the best cuttings – as long as they’re not blooming yet. Spring cuttings take much more quickly than fall ones – fast enough that we should have more plants to tuck in later where we need them.

Make sure the cuttings are neither floppy nor woody. Trim off the second or third set of leaves from the top right at the stem using a sharp knife or razor blade. Trim the remaining leaves in half, dip the end of the stem in rooting hormone, and stick it in dampened  sterile rooting medium like perlite or vermiculite. If you don’t have a high-tech mist system like we do, put a low-tech clear plastic bag over the cuttings and mist them with a spray bottle occasionally. Keep them in a bright warm spot out of the sun and they should root in 2-4 weeks. Pot them up for few weeks before planting them out.

Other plants on our pinch-now list are the ones that bloom late in the season like chrysanthemum, which can be pinched again around Father’s Day; Boltonia – I swore last year that I would pinch ‘Nallie’s Lime Dot’, and Helianthus – ‘Lemon Queen’ to keep them from keeling over; and rabdosia (trumpet spur-flower). We also sometimes pinch summer phlox – but only if we don’t want them to get too tall (otherwise we’ll just thin out some stems to give them better airflow); dahlias if they’re up and leggy, Salvia, and potted annuals when we plant them even if they’ve already been pushed into bloom.

What plants are you pinching back now? Are you squeemish about doing it too?

For this mid-May Garden Bloggers Bloom Day hosted by Carol at May Dreams Gardens, I’m going to postpone the usual list of all of the amazing things that are blooming suddenly all at once and go into euphoric raptures about a single fantastic genus that has been blooming for a while now. One of them even kept last year’s blooms all winter.

Of all 2000 odd species of euphorbia in the world, we only have a half-dozen or so on the property. In a way that’s plenty because the ones we have are pretty great, and on the other hand it’s not nearly enough because who wouldn’t want more?

At the top of my favorite spurges list is Euphorbia x martinii ‘Ascot Rainbow’. Not only does it have stunning multi-colored foliage and fabulously intricate flying-saucer blooms but it looked fabulous through the winter. In fact, it still looked so good this spring that we weren’t sure if we should cut it back. We decided to cut a few plants here and there to within a couple inches of the ground, and we left a few standing, and are planning on using their older stems for arrangements. That’s one of the greatest things about euphorbia: they make really great nearly ever-lasting cut flowers.

Euphorbia amygdaloides ‘Purpurea’ (below left) spreads generously (rhizomatously) in shade but we have it in full sun too in the Rose Garden. We transplanted bunches of it around from underneath the chestnut rose and it pouted for a good year (or was it two?) before finally looking stunningly settled. Never give up on a euphorbia. Last year we also planted ‘Craigieburn’ (below right) in the cutting garden I think I like that one even better for the subtle range of colors in its foliage and the extra acid in the green of its flowers.

E. longifolia (below left) has been seeding itself around the North Garden and Display Garden for years, which is great because we always have the option of using it where it lands or hoiking it out to make room for something else. After it blooms (it stands about 2′ tall) we cut it back hard to encourage a new flush later in the summer. That’s a dangerous job because the sap of this one seems particularly caustic. Anyone who has ever gotten a bright red burning and wicked-itchy rash from spurge learns pretty quickly to wear body armor to work with it.

The cushion spurge (E. polychroma – above right) in the Rock Garden hasn’t self-sowed although it’s supposed to and I wish it would. It’s too cute. We also have ‘Bonfire’, which has bright orange blooms and red foliage, up in the Display Garden but we don’t have it in enough sun to show itself off properly.

I could go on because we also grow sticks-on-fire pencil cactus and crown-of-thorns in the greenhouse and those go to show how varied the genus can be. But I’m stuck on spurges. Which ones do you grow – or wish you did? For a look at what else is bloom (besides euphorbia) all over the country and the world, click on the links listed here.