If there's one plant that loves our summers, it's the bougainvillea. The hotter it gets, the better they get, or so it seems.
Actually, bougainvillea blooms best on days short on daylight. But that's not really what this week's tip is all about. It's about making the bougainvillea ("the bogey," as we'll call it here) bloom better.
A question I get often on the radio program is, "my bogey is growing well and looks healthy and green, but what can I do to improve its blooms?" The answer is (and lazy gardeners will love this), torture it! Make it suffer!!
First, when we talk about a bogey "blooming," it's sort of a misnomer. The beautiful pink, red, and orange colors aren't blooms at all ... they're modified bracts, sort of like a poinsettia's modified bracts. The actual bloom is the little tube with an inconspicuous white or yellow flower on the end. But to make a bogey "bloom" better, we need to apply some stress. And we can do that in a couple ways.
If the bogey is in a container, it should be deprived of water until it wilts pathetically. Once you decide it has wilted enough, water it and keep it well-watered from that point on. The stress, along with some appropriate food which I'll get to below, and some selective pinching back of longer branches, will force modification of the bracts.
If the bogey is in the ground, and you can't deprive it of moisture because of automatic sprinklers or rain, then you must abuse the bogey by selectively severing its roots. Use a sharp-bladed shovel and make cuts into the root system about two feet away from the trunk. Make a cut, skip a shovel width, and make another cut. Cut, space, cut, space, cut, space, etc. Also, pinch back some branches here and there.
In both cases, it's essential to feed the plants at least once a month with something like a hibiscus food. Yes, there are a couple of bougainvillea foods on the market – Nitro-Phos 4-pound jugs (below) and Nelson Plant Food’s NutriStar for Hibiscus and Flowering Vines - but if you can’t find those, any hibiscus food is a darn good replacement. You see, hibiscus fertilizers are normally higher in nitrogen and potassium than they are in phosphorous (the middle number), and that's what we want, because we aren't trying to make it "bloom" the way we do with flowers. Containerized plants actually like water-soluble plant food better, and there are not a lot of water-soluble hibiscus foods sold around here, other than Carl Pool's Hibiscus Food and the locally exclusive food from the Space City Chapter of the Hibiscus Society. However, you can use any simple 1-1-1 water-soluble plant foods for containerized bogeys with confidence.
One more note: In most cases, bogeys actually don’t need the best soil.That doesn’t mean use peat-based soil, which I abhor. It means the more loam or clay the better. You’ll see some of the best-looking bogeys in rocky but mineral-rich soils, like in the Hawaiian Islands or at Mexico’s rocky shoreline resorts. Some of the best I’ve ever seen were growing an interesting combination of crushed granite and volcanic rock on the isle of Crete in the Mediterranean.