What to Do with Peonies this May for Bigger Blooms and Longer Lasting Displays – 3 Easy Steps You Must Take Before It’s Too Late

The wait is almost over, and if you’re anything like me, the anticipation is unbearable. Chances are, for the last few weeks, you’ve been peering at those pink asparagus tips, willing them on as they unfurl into lush bushes. Now, the finish line is in sight. My herbaceous ‘Coral Sunset’ peonies have reached that tantalizing marshmallow stage, by which I mean their fat buds are getting squishy, hinting at blooming peony displays so spectacular yet still elusive, teasing me every time I walk past.

But here’s the thing about peonies: those last few weeks before blooming can often be the most critical. You see a slightly floppy marshmallow stalk listing after heavy rain, lean over to nudge it into a support, and hear that sickening snap (believe me, I’ve been there). After all this patient waiting, the last thing any of us wants is to sabotage the grand finale with silly oversights and ill-advised last-minute peony fixes. And the worst thing you can do for your peonies this month is... nothing at all.

While they don't need us to hover over them, a few simple steps this month can ensure your precious marshmallow buds reach their full fluffball potential and don’t wind up face down in the mud. Don’t panic, you’re nearly there: you just need a few minutes and these last checks to make sure your herbaceous favorites can turn fat, happy buds into magnificent blousy peony blooms.

Get Ready for the May Growth Spurt

By the time May rolls around, it might feel like it’s too late to do much for peony size or peony bloom time, but we can be effective in the weeks before herbaceous and Itoh varieties bloom – and in the days after tree peonies are fading. Even when peony clumps seem to be putting on several inches of growth overnight, we can determine the fate of those massive fluffy heads in simple, straightforward ways.

Depending on USDA zones, May weather can be fickle. One week we’re dealing with a heat spike that seems to wilt tender stems. The next, a downpour threatens to batter healthy foliage (and nascent blooms). A few small environmental checks can make a big difference. This isn’t the time for nitrogen-heavy peony fertilizing which can trigger weak, sappy growth. That said, I do like to add a gentle splash of seaweed in spring, like Neptune's Harvest Fish & Seaweed Fertilizer from Amazon. This contains micronutrients and hormones that support flower strength at this volatile time, and serve as a vital plant tonic to intensify eventual bloom color.

Caring for peonies in spring isn't about grand gestures. If it’s turning out to be a wet spring, airflow is key. If it's a dry one where you are, deep hydration is the goal. It’s about responding to these shifts with a steady hand to nurture peony bloom. With these few high-impact tasks, you’ll ensure your peonies have the structural integrity and health they need to withstand whatever the skies throw at them. Here are the small steps you need to enjoy those big, pillowy peonies you’ve been waiting for.

1. Support Your Peonies

Rainwater and wind can be a devastating combination for peonies in May. One should never underestimate the weight of a rain-soaked 'Sarah Bernhardt' on the verge of blooming. And nobody wants to see our beloved peonies face-down in the mud. Because May growth can be explosive, this is your absolute last call to get peony supports in place – but do make sure they are the right kind.

Not all peonies need scaffolding. If you’re growing Itoh hybrids like 'Bartzella,' you’ll find they’ve inherited the stiff stems of their tree peony ancestors. For herbaceous types, though, you may need to bring in reinforcements late on. Don’t wait until the plant is flopping to try to secure it with twine or, worse, cages. Frames and cages are great when peonies are young enough to wind through them naturally as they grow. But once you are staring at 20-inch (50cm) tall peony stalks, it’s too late to twist brittle stems into these plant supports. Even if you don’t risk snapping stalks, you might choke off airflow and invite disease.

If you missed the window for grow-through grids, don't panic. Place three or four sturdy bamboo stakes around the perimeter of your peony clump, with another in the center, then weave soft twine between them. This allows individual stems to lean naturally while staying upright. You can also link together individual stakes designed to be connected for a last-minute show of strength. You can buy GiCare Peony Plant Connecting Stakes from Amazon, which can be linked together around developing plants in a gentler way than a cage. Use Velcro Adjustable Plant Ties from Walmart for another level of reinforcement. Be sure to check your supports weekly.

2. Watch Out for Disease

The sadness of a peony bud that fails to open is hard to put into words. Watching a fat, promising bud suddenly turn brown and shrivel up is genuinely upsetting. You may think this was due to a late frost, but more often than not, this is likely fungal disease in action, especially if you have also been forcing peonies into cramped cages with spring rain in full swing. One of the most common diseases for peonies is botrytis blight, a fungus that thrives in damp, humid conditions. Botrytis loves the tender tissues of emerging buds. Swift action is crucial: if left, the fungus can travel down the stem and infect the crown, weakening the plant for years.

So the second of your easy checks this month is to check your precious marshmallow buds. What you are looking for is bud blast: this is evidence of buds that have turned black or dark brown or feel mushy. If you see one, don't panic. You’ve likely caught it early, and stopped it getting worse. Simply snip it off, and remember to sanitize as you go. Keep a small jar of rubbing alcohol or a 10% bleach solution handy to dip your snips in between every single cut. You can get Epic Medical 70 Percent Rubbing Alcohol from Amazon. This prevents you from accidentally hitchhiking spores from a sick stem to a healthy one.

If you see ants crawling all over your 'Karl Rosenfield' buds, it’s not as bad as you think. While they look like trouble, they are just sipping the nectar the buds secrete and, in exchange, deterring other sap-sucking pests. As long as the buds look green and healthy, let the ants do their thing. You can protect foliage from the risk of gray mold without harming the ants, by applying a gentle foliar spray. Try Bonide Captain Jack’s Copper Fungicide Spray from Home Depot. It’s also wise to thin out any spindly stems that don't have buds, to make it harder for mold to settle in.

3. Check Mulching and Watering

If you want to gaze into the future with peony health, look into the eyes. These pink buds on the crown are where a lot of the magic happens, from flower size to strength of stalks. Hopefully, you sorted out a good mulch for your peony, but now is a good time to inspect moisture levels and see how your mulch is doing. Your third check is to make sure peony eyes aren’t sitting too deep in the mulch. Since there’s more activity around beds in spring, it’s possible for mulch to get kicked over crowns. Burying the crown even by 2 inches (5cm) can tell a plant it’s too deep to bloom. So pull back any mulch from the center, leaving a 3-inch (8cm) circle around stems.

Deep hydration is also important in May, especially if you are having a dry spring or live in the south or west. Inconsistent moisture during the bud-swelling stage leads to smaller, shorter-lived blooms. And a sprinkle only wets the surface and encourages shallow roots. Aim for a long, deep soak once a week, early morning or evening, and target the base of the plant: water the toes, not the nose!

A soaker hose can deliver water directly to the root zone. Try the Gilmour Vinyl Soaker Hose from Lowe's to automate the process. You can also get individual drippers that work even if you don’t have a full irrigation system set up. Try an emitter like the Rain Bird 2 GPH Spot Watering Emitters from Home Depot. Just avoid overwatering, as this can encourage botrytis.

Bonus Checks for Post-Bloom Care

While herbaceous peonies are just approaching bloom time, many tree peonies are already taking their final bows. If you’re lucky enough to grow these woody wonders, May is a critical month to ensure the longevity and vitality of future blooms. As those blooms fade, your tree peony puts its energy into producing large seed pods. Leaving these to develop is exhausting for peonies, especially when you have no intention of propagating more by seed. So deadheading these flowers is critical, using clean, sharp shears. Industry-standard Felco 2 One-Hand Pruning Shears from Amazon give a clean, bypass cut that won't crush the cambium layer.

By snipping off the spent flower heads now, you trick the plant into redirecting energy into root development and forming buds for next year’s show. Prompt deadheading also helps reduce the risk of fungal spores hitching a ride on decaying petals. So remove just the flower heads, cutting above the first set of true leaves. Keep everything tidy with pop-up gardening bags like Fiskars Kangaroo 10-Gallon Collapsible Gardening Bags from Walmart. Whatever you do, though, don’t cut the tree to the ground. This quick tidy-up ensures a stronger, more resilient tree peony.

Shop Peony Care Essentials

Keeping on top of peonies deserves a treat. These key essentials don’t just make the chores easier but create an element of indulgent ritual. Just like peonies, the right tools, treatments and accessories can keep you company for years to come. So treat yourself, and your peonies. These curated picks will help nurture your favorite plants towards a glorious flowering finale – and set them up for years of future blooms.

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