August is all about the Z-Grass!

Zoysiagrass needs TLC in August

In direct contrast with cool season lawns, which shouldn’t be fertilized with high nitrogen in the sultry months of July and August, zoysiagrass, and it’s hooiser cousin, bermudagrass, LOVE nitrogen and heat! Zoysiagrass and bermudagrass are WARM season grass species. For those of you that vacation in the south, they have additional varieties like paspalum, St. Augustine and centipedegrass, all of which have broad leaf blades. The latter three species can’t handle the cold weather. Zoysiagrass is more cold tolerant than bermudagrass.

A great program for zoysiagrass in the transition zone follows:

  1. A thick and healthy zoysiagrass lawn may not even require a preemergence application for crabgrass! If you have a weaker lawn, or one you’re trying to establish, apply a crabgrass preventer in mid-April on a fertilizer with at least 18% nitrogen. Apply the crabgrass product as late as possible, when the soil temps approach 50 F. You really don’t want to put this down on dormant zoysiagrass. Our local meteorologists on Fox 2 in STL give soil temperatures in the early spring, so pay attention to their forecasts!
  2. Systemic Insect Control on a High Nitrogen fertilizer should be applied in mid-June. Zoysiagrass has more problems with billbugs than grubs, and the systemic products control both. Professional bags are 50 lbs and will treat 12,500 sq ft to 14,400 sq ft. This bag will last 2 years no problem. If you can’t find a professional supplier you can purchase a systemic insecticide at Home Depot or Valley Park Elevator. Your z-grass needs 0.75 to 1.0 lb of actual nitrogen per 1,000 sq ft. To calculate how much nitrogen is in the bag, multiple the weight of the bag times the % nitrogen (first number) in the bag. For example, a 36 lb bag of 24-8-12 has 8.6 lbs of nitrogen (36 X 0.24). Round down to either 8 or up to 9 without worry.
  3. One last shot of nitrogen between July 24 and August 15. Again, 0.75 to 1.0 lb of actual nitrogen.
  4. NO MORE NITROGEN THE REST OF THE FALL!

MOWING RECOMMENDATION:  Zoysia does better when it’s mowed low. As low as freakin’ possible! If you mow it high, it won’t spread very aggressively. When you mow it low, it’ll spread very nicely for you. Z-grass has a tough leaf blade so keep the blade razor sharp. Don’t mow more than 8 times without sharpening or changing your blade for best results. A lawn mower engine won’t last as long mowing Z-grass as it does a cool season species. If you’ve got a small lot in the city, get one of those new, lightweight “reel-type” mowers. Those are kick-ass for zoysia because the cutting action is “scissors-like”.

WATERING RECOMMENDATION:  Z-grass really only needs an inch a week to grow well, because it is adapted to hot weather. We have to water the crap out of our bluegrass and fescue lawns to keep them from going dormant! Stop watering zoysiagrass after September! Let it start to go dormant in October.

AERATION AND DETHATCHING:  You should NOT aerate or dethatch zoysiagrass unless it’s 100% green and growing. Do this in early June when the temps are tolerable for you to clean up the mess. Water and fertilize when you’re done. Mow low and watch that sward develop!

Many of the lawns in St. Louis are blends of both cool season lawns and zoysiagrass lawns. Bermudagrass is a weedy invader via bird poop, but zoysiagrass doesn’t become established the same way. If you don’t want the warm season grass to expand, then be sure to AVOID passing through these areas when you aerate, because you’ll “spread the sprigs” in the cores! If you desire more zoysiagrass in your cool season sward, then aerate around mid-August. Be sure to water to allow the small pieces of stolons and rhizomes to become established.

FUNGICIDE IS OCCASIONALLY BENEFICIAL:  Zoysiagrass in St. Louis was plagued with a disease called zoysia patch during the summers of 2013 to 2016. It was devastating to many lawns, especially for those of you that followed the cultural recommendations for cool season lawns. Factors that exacerbate zoysia patch are aerating/dethatching before June or after September, watering all fall and fertilizing after September.

The pathogen that causes zoysia patch is Rhizoctonia solani, but a slightly different sub-species than the one that causes brown patch in cool season turf! Fungicide applications are really only useful when daytime temps are near 70 F. Apply Headway G fungicide in the fall and again in the spring. If you can’t find Headway G combine the two products you can buy at Home Depot–azoxystrobin and propiconazole. It is very important to time the application to 70 degrees! This is because of the infection cycle for the pathogen.

Here are a few shots of zoysiagrass, mowed at three inches, which is very common in St. Louis. The photo on the left is all zoysiagrass, while the photo on the right is the interface between zoysiagrass and the cool season species.

A new variety of zoysiagrass has a slightly darker green color than ‘Meyer’, the long-dominant variety in our area–called ‘Zenith’.  Emerald View Sod Farms in Columbia IL and O’Fallon MO carry this variety. Call them and ask if you can get it here in town. Or, just go there.

 

 

 

Mid-June is Grub Control Time

Apply Insecticides Now to Kill Baby Grubs

Mid-June in the Transition Zone is the right time to kill the newest batch of grubs that feed on grass roots. There at nearly a dozen different species, but the dominant beetles that make grubs in STL are the chafers and the Japanese beetles. The B-52 sized June bug is less common, but when you come across a June bug grub, it’s freaky huge! You’ll scream like a sissy. If you’re unsure what a grub worm looks like, just Google it. [Are you shittin’ me? Don’t know what one looks like? Oh wait, I forgot that most millennials spent all their time in the basement playing video games!]

Eggs hatch and the larvae will eat the roots of turf. Egg hatch in STL is usually complete for all the species in early to mid-August. Grubworms go through a series of instar stages (molts) getting larger with each molt. Insecticides applied right now do a better job of killing the little babies while they’re small. We apply our systemic insecticides in mid-June so that the turfgrass has plenty of time to absorb and translocate the insecticide throughout the plant. Grub bites root—grub gets upset tummy—grub dies! Contact insecticides area applied in mid-August—because they don’t need to be taken up by the turf roots. Mr. Grub just digs and eats—insecticide washes over the poor baby—grub baby dies!

I will tell you now that the systemic products are more effective than the contact products for killing grubs. In dry years when the grubs are deeper in the soil, the contact products can be diluted in soil profile, and thus, less effective overall. They work great when the grubs are closer to the soil surface. On the other hand, contact products also kill fleas, ticks, spiders, crane flies, crickets, and a host of other bugs.

Grub damage tends to be patchy. Even when grubs are heavy in area, there will be individual clumps of surviving fescue plants—think “hair plugs for men!” This picture below captures the essence of a fescue lawn with grub damage. Note the relatively large patch of mostly dead grass. But note that there are several hundred individual clumps of grass (mostly fescue) that have survived! Some grasses contain an “endophyte” fungus that lives in the roots of infected plants. Grubs don’t like the alkaloids (natural insecticide) that the endophyte produces. Therefore we get this type of response–very clumpy. Kinda like “hair plugs for men!” Grubs don’t destroy 100% of the turf in the patches they infest.

Grub Damage

Healthy, irrigated turf in STL can usually handle 10 or so grubs per sq ft, but crappy turf can’t. Weak turf might only tolerate 3 to 5 grubs/sq ft. When grub populations are extreme you can literally pick up turf like a throw carpet! I’ve seen this only once in my career, and the grubs were massive June bug grubs!

Below are photos of the 4 most dominant products sold for grub control. Be careful to use the right dose for grubs! While the bag may state, “Treats up to 12,500 sq ft” that’s for the surface-feeding insects. I’ll discuss their active ingredients, pros and cons, and cost  from my local Home Depot (Lowe’s sucks, by the way).

Spectracide Triazicide Insect Killer:  Contact Insecticide (cyhalothrin). Apply early to mid-August for grubs, but anytime for fleas and ticks. A 20 lb bag costs $13 and treats 16,600 sq ft. $0.78 per 1,000 sq ft.

Roundup Bug Destroyer: Systemic Insecticide plus Contact Insecticide (chlorantraniliprole plus bifenthrin). Apply early to mid-June. A 10 lb bag costs $17 and treats 2,500 sq ft. $6.80 per 1,000 sq ft.

Scott’s Grub Ex: Systemic Insecticide (chlorantraniliprole). Apply early to mid-June. A 14.5 lb bag costs $21 and treats 5,000 sq ft. $4.20 per 1,000 sq ft.

Bio Advanced Grub Killer Plus:  Contact Insecticide (trichlorfon). Apply to mid-August. A 10 lb bag costs $19 and treats 5,000 sq ft. $3.80 per 1,00 sq ft.

Ortho Bug Be Gone:  picture not shown. Bifenthrin contact insecticide. Special sale–10 lb bag for only $7.00. Treats 2,500 sq ft. $2.80 per 1,000 sq ft.

Professional Blends on Fertilizer Granules:  Many professional LCO’s use non-nitrogen fertilizers with systemic insecticides (typically imidacloprid or acelepryn) at the recommended application time

If I were hosting a garden party, I’d purchase Triazicide and apply it a week ahead of time, to cleanse the area of surface pests. But for grubs, I recommend the systemic insecticides.

No get off your arse and apply your insecticide now!

Trav

 

 

 

Brown Patch: the big nasty turf spoiler

Rhizoctonia solani…

Brown patch is caused by the ubiquitous pathogen, Rhizoctonia solani, and it infects virtually every species of turf in the US. Tall fescue and turf-type fescue is far more susceptible than Kentucky bluegrass, but the latter gets it, too. In zoysiagrass this same organism causes zoysia patch disease. For you golfers, blame those ugly summer greens on brown patch! Seedling turf is extremely susceptible to brown patch, which is why most experts discourage spring seeding.

The fungi lives on decaying organic matter in our lawns, at the interface of organic matter and the soil surface. It rears its pathogenic side during prolonged periods of hot and humid weather, especially during dry spells. You can bet your bum that when the dew points and the night time lows are in the 70’s, we’ll have an outbreak. For photos, just Google “brown patch in fescue turf” for more pics than you can handle. I’ll tell you right now that 95% of disease in Midwestern transition zone turf is brown patch.

There are numerous cultural practices that you should employ in an attempt to minimize the impact of brown patch on your lawn, but to really control this disease, you’ll need the help of fungicides. First, let’s talk about those things you can manage from a cultural perspective.

  1. Keep the blade sharp:  No, I’m not talking about the 7 habits bull crap. Literally. Keep. The. Blade. Sharp. (My daughters tell me this infers extreme emphasis…does it?) Come mid-May, you should be sure to have a brand-new sharpening job on that blade. Buy an extra and always have a sharp one handy.  Don’t go more than 3 months without sharpening your blade (average homeowner).
  2. Keep the deck high:  Mow cool season turf in full sun at maximum height on your mower. 4 inches is better than 3 inches! For cool season turf in good shade, you can mow lower, say 2.5 inches, because you don’t want turf to stay wet from dew, irrigation or rainfall excessively long. If you’re serious about being the beast of turf in your neighborhood, you should have a reasonably new mower, capably of 3.5 or 4 inch mowing heights.
  3. Water in the morning:  All diseases need moisture for the spores to germinate and grow. Watering at night keeps the grass covered in a film of moisture all night long. Thus, more disease.
  4. Bag your clippings in the dog days of summer:  Bagging the diseased-laden grass when the outbreak is bad has been shown to reduce the spread of the disease. When you’re miserable outside so is your turf. I like to tell folks when the heat index is above 90F, your turf isn’t happy. When the heat index is above 100F, your turf is pissed at you…for watering it, fertilizing it, and doing all those things to keep it from going dormant.
  5. Avoid excessive nitrogen in June, July and August:  Points 1 to 4 are important, but my experience shows that 90% of you with terrible brown patch used the wrong fertilizer at the wrong time. Anybody putting traditional, synthetic fertilizer formulations down after mid-May is begging for the disease. You don’t want soft and succulent turf around when the conditions are right. The biggest national brand sells stuff so high in nitrogen it should only be used on zoysiagrass in the summer. Weed-and-Feed formulations are terribly high in nitrogen. They suck! Both for killing weeds and too much N…I’ll save this rant for later this summer. Seriously, cool season turf in St. Louis and the rest of the transition zone should get 75% of its nitrogen in the fall, to support the plant’s natural growth cycle. Using high nitrogen fertilizers in the early spring isn’t a death knell, but your crabgrass product is best with 12% or less nitrogen. Retail stuff sucks, with 24% or more nitrogen in the bag. And retail stuff has a crappy herbicide, too. Your grass will green up wonderfully in the spring if you do most of your fertilizing in the fall. The astute reader is now asking herself, “Well then, what the hell SHOULD I use in the summer?” I love organic nitrogen in the summer, but ONLY for irrigated lawns. I especially like Milorganite (and the knock offs) for irrigated turf, because it has low nitrogen content, all slow release, and a lot of iron. If you’re not irrigating, don’t fertilize after your crabgrass product goes down. Reread that–if you’re NOT irrigating in the summer–DO NOT fertilize in the summer!

Fungicides

It’s important to use the right product for control of brown patch, which is azoxystrobin (I pronounce it “a-ZOX-e-stroh-bin”, but I’m not the sharpest tool in the shed!). A disease program MUST contain this active ingredient, proven by universities to be the best single fungicide for brown patch. However, it should not be used alone! The best companion product is propiconazole (pro-PEE-con-a-zole).

Fungicides aren’t cheap. Actually, they are very expensive, especially considering you need to apply them every 3 to 4 weeks during the dog days. No matter the product you use, read the label and follow the coverage recommendation for brown patch. If you stretch it too far you’re wasting your time and money. Just burn those bills on the BBQ…or better yet, send them to me!

There’s a commercial product available at professional turf outlets called Headway G.  A 30 lb bag covers 10,000 sq ft on a preventative basis, but only 5,000 sq ft on a curative basis. If you’re just now reading this (mid-June-2018), your first application is in the CURATIVE dose rate. When I was in the business we’d instruct our Sward Masters to make their first preventative application a full week ahead of the prolonged 90 F degree weather forecast.  If we get a wonderful clearing cold front that drops our temps and humidity, stretch it to the 4 week interval.

The photos below show the Scott’s product containing azoxystrobin (DiseaseEX) and the Bayer product with propiconazole. I’d recommend you buy both for your first shot. Apply them both, individually of course, if your lawn is suffering terribly. Each bag covers 5,000 sq ft. Used alone, the manufacturers suggest applying every 2 weeks in miserable weather, every 4 weeks otherwise. But that’s used alone.

After application water well, in the AM. Then in 3 weeks apply azoxystrobin again. Three weeks later apply propiconazole. Repeat until the cool weather arrives (crap, that’ll be October!). And oh, by the way, don’t count on 100% control! Ain’t gonna happen. Be happy with 80% control.

Let me know if you give these products a go!

Stay Cool!

Trav

 

THIS STUFF WORKS!

Bayer 3 wayI grew tired of watching some of my landscape ornamentals get hit with powdery mildew every summer. A buddy of mine with a lot of pathology experience (pun intended) suggested I try the fungicide tebuconazole as a preventative root drench.

So, I found this product on the shelf, Bayer Advanced All in One Rose and Flower Care.  In addition to fungicide it has a systemic insecticide (imidacloprid) and some fertilizer (9–14-9). I was also sick of black spot on my roses, which this controls. The insecticide controls feeding adult Japanese beetles, a huge plus, aphids, scales, leaf miners and a host of other pests.

So I bought it and put it to the test. The general directions are 2 fluid ounces per plant, or 2 fluid ounces per 12 sq ft of general mass plantings, as a drench in 1 qt to 1 gal of water.

Back in early May I treated my roses, a 16 ft tall native flowering dogwood, ‘Mrs Moon’ lungwort, two peonies,garden phlox, woodland phlox and a mass planting of Monarda (beebalm). Interesting that every beebalm in my bed was advertised as resistant to powdery mildew! Total crap in St. Louis! I’m impressed! Especially with the lack of mildew in my Monarda bed! Directions say treat every 6 weeks, which I intend to do, because we’ve got another two months of mildew enhancing weather!

Stay tuned!

Trav

How Large is Your Sward?

Hey folks, when it comes to taking care of the yard, aka “the sward”, the absolute very first thing a do-it-yourself (DIY) lawn tender MUST know is how many thousand square feet of actual TURF one has. Back to the sward comment…a crappy yard is not a sward! Only a beautiful yard, one that creates envy, can be called a sward!

This is a serious matter, because success or failure in your lawn care practice is based upon the PROPER DOSE. It’s important for fungicides, herbicides, insecticides and especially fertilizers. Think about it for a second. If you apply a bag of insecticide designed for 5,000 sq ft over your 12,000 sq ft lawn, do you think it’ll work properly? Hell no! And when you apply a 50 lb bag of fertilizer with a 24-8-12 formulation over a 5,000 sq ft lawn, would you expect success? The aforementioned bag of fertilizer has 12 lbs of actual nitrogen in it (50 lbs x 0.24 = 12), and thus would cover 12,000 sq ft of turf in the fall. Put that much nitrogen on a tiny yard and you’ll have a dead lawn after about a month of summer heat.

Back in 2012 when  I was with THE Turf Plan, I penned a nice blog about this. Rather than regurgitate it, I’ll recycle it! Go to this link on THE Turf Plan website and read up:  How Large is Your Sward.

You needed get carried away but get within 10% accuracy. Don’t be a dumb ass! Figure it out.

Success will follow!

Trav

 

 

 

 

 

 

Gimme More Sunshine!

competitionSpring has been reluctant for us St. Louisans, but I’m not complaining! I’d rather have a slow start than a quick warm up and a disastrous freeze!

That said, many of you are already thinking about creating new beds, renovating beds or just expanding them. The picture above may be a little dark, but it tells a great story. Zoom in to see that little sucker on the far right. About 4 years ago my neighbor planted 4 new hostas (‘Francee’, nothing special), all purchased from a big box store and approximately the same size. She planted them 3 feet apart in a decently ammended clay loam soil.

I took this photo last June, because it really shows how competition for sunlight, water and nutrients affects plants. The hosta on the far right is really about 1/4th the size of the hosta on the far left. There’s a very linear reduction in plant size from left to right. Because this neighbor tended to overwater I don’t need to go out on a limb and say that the size gradation is the result of competition for sunlight.

Keep this in mind when you’re planning and planting. Few plants enjoy being directly underneath a thick canopy. Even the shade tolerant hosta shows a preference for being out from under that canopy of this ‘Forest Pansy’ redbud. If you want to plant underneath an established canopy, be sure to limb up the branches ahead of time, and consider thinning their crowns, to allow more sun to hit the soil beneath.

 

You Shouldn’t Have Crabgrass!

It’s mid-March so the lawn care operators (LCOs) are applying their Round 1 product, consisting of fertilizer plus crabgrass preemergent herbicide. LCOs start early because it’s better to be early than late! However, any company applying a crabgrass product now MUST also apply a SECOND SHOT of crabgrass preemergent (late April to mid-May). The exception to this rule is for superb lawns, where the healthy sward is so thick and lush that crabgrass seeds have no chance to contact the soil surface. BTW, for the do-it-yourselfer it’s too early. You can wait until at least April 1st.

Nothing chaps my ass like seeing these application notifications where the company made an application over a crap ton of leaves and debris! This is usually where the damn crabgrass is going to be bad! Your lawn care company should have given you a heads up a few weeks in advance, saying something to the tune of, “Dear Customer, we’ll be applying your first round of fertilizer and crabgrass product in mid-March. Please do your best to get the leaves and organic litter cleaned up, so that our product can do its job!” This is why THE Turf Plan is so successful, because they send you timely emails–educational and informative (check out www.theturfplan.com). Your local LCOs will do a far superior job than the national chains.
If you have crabgrass in your lawn, FIRE your LCO! Right now! Crabgrass preemergent herbicides are extremely effective, so there is zero excuse for crabgrass in your lawn! This is especially true if you’ve given your LCO more than one season of business. To further reinforce this point there are new products that can be used postemergent (after the weed comes up), meaning your LCO can clean up any mistakes in mid-May.

There 3 common preemergent crabgrass herbicides that are combined with fertilizer products. The absolute best is dithiopyr (Dimension®), the second best is prodiamine (Barricade®), and the really sucky one is pendimethalin (Pendulum®, favored by that national brand!). I rank Dimension as #1 because it will actually kill small (1/2 inch or less) emerged crabgrass. If you’re a week or so late with your first shot, Dimension can kill those early emerging crabgrass plants. Look the bag over carefully and avoid pendimethalin–unless you’re sure you’ll apply that second shot. But be warned, products with pendimethalin usually have WAY TOO MUCH nitrogen (anything over 18%). You don’t want to apply a lot of nitrogen in the spring.

Crabgrass will emerge when soil surface temps reach 55F for about 3 nights in a row. If you live near agricultural areas, when the farmers start planting corn, you need to apply your first shot of crabgrass preventer. Suburbanites can use a phenological indicator, the forsythia bloom, as a guide. However, it’s not the BEGINNING of the forsythia bloom, it’s towards the END of the forsythia bloom that is more accurate (wait for that third week of yellow).

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No Way You’re Gonna Straighten That!

IMG_3240.JPGIt is hysterical that folks think they can straighten trees this way–simply not possible! Those t-posts are too weak and that tree would need massive 4 x 4 posts planted at least 2 ft into the ground. Heavy gauge wires would be required, too. Save yourself the trouble. Save yourself from looking like an idiot!

It drives me nuts at how many new landscape plantings have leaning or crooked trees, but I know why it’s happening, for two reasons.  First, in commercial plantings, where big landscape installers do the planting, they use heavy equipment with huge augers, and the root ball has “way too much room” in that hole. Then their workers backfill the holes without tamping/firming the soil around the root ball. Thus, the tree is free to flop around in the wind. It is especially bad with evergreens because they present considerably greater wind resistance than deciduous trees.

Now you’re thinking, “OK, Jeff, what should I do if my tree is leaning?” Well, first of all, when you plant a new deciduous tree or evergreen, DO NOT use “great soil” to backfill the hole. Use your native soil, or amend it just slightly to improve it; avoid using that fabulous “bagged dirt” with peat, compost, vermiculite, etc. That stuff won’t compact and your tree will flop in the wind. If you have nothing but rocky soil, just use plain ‘ole bagged topsoil as backfill but use as many of the clay crumbs as you can.

Reason 2 for crooked trees, for the average Joe. What I will say next is sure to piss off the PROS, like the university extension folks, the master gardeners at MoBot, and the published authors–DO NOT make your hole “twice as wide” as the root ball. This will give you a floppy tree for sure. Dig the hole about 1 to 2 inches more shallow than the root ball because you do not want the crown of the plant to be lower than grade (potential rotting issues). Dig the hole only 6 to 8 inches wider than the root ball, just wide enough to use your foot on all sides to tamp the soil back into the bottom third to half of the root ball. As you backfill the hole, continually insure that your tree is straight on ALL views. Make sure the more critical spouse is present during planting, so that the new tree is perfectly straight. I’ve planted hundreds of trees this way and seldom had a crooked tree! If your tree does lean, you’ll need to fix it ASAP. Don’t just push on the tree trunk, though, and for goodness sakes, DON’T STAKE like this photo.  For example, if the tree is leaning 10 degrees due north, you’ll have to dig up some soil on the outside of the root ball on the north and the south sides. For this example, use a spade on the north side to pry the root ball sufficiently so as to level the tree trunk. Then tamp the soil EXTRA firm with your foot. Digging on the opposite side (south in this example) facilitates repositioning the root ball. Tamp the soil back in on the opposite side, too.

SIDEBAR: don’t remove the burlap from the root ball, or the wire basket (if present). Cut the twine off of the tree trunk, to avoid girdling the trunk. Make sure that burlap is not exposed, because it will wick water from the root ball. I recommend cutting the top of the burlap off AFTER the tree is planted.

And oh, by the way…cut that ugly tree down!

 

 

Kiss Your Buds Goodbye!

Unseasonably Warm Weather

St. Louis and much of the Transition Zone has “benefited” from unseasonably warm weather in November, after some good, cold weather in October. This weather pattern has totally confused our landscape ornamentals, especially beautiful flowering shrubs that bloom on old wood–such as the Bigleaf Hydrangeas (Hydrangea macrophylla cultivars). Plants in our region are programmed to go dormant, based upon either short days and/or cold temperatures. Think about this. To survive our cold winters, plants need to hibernate. Each species has a different chilling requirement (hours of cool/cold weather at a certain base temperature) and those plants that are adapted over a wide geography (such as the showy bigleaf hydrangeas) tend to require too few hours of chilling. As such, they are prone to making mistakes. A good example of how this works is the apple tree. At the risk of oversimplification, an apple tree needs 600 hours below 45 F. This is why Georgia grows peaches and very few apples!

The featured image shows an actual flower bud on the popular ‘Nikko Blue’ selection, taken just a few days ago. The buds emerged in mid November, only to be killed by one of our frosts. These buds should have opened next May! Those of you with these plants know how disappointing they have been these past few years. They were so gorgeous at the nursery! I did some research on the various reasons for flowering failure in this species. Breeders of these cultivars are working on improving heat tolerance, because prolonged hot weather decreases flower bud set. Another obvious need is better cold tolerance. For maximum success here in St. Louis, try to locate your bigleaf hydrangeas on an east or southeast exposure with good protection from winter winds. Shade after 1:00 PM or 2:00 PM is perfect. If you’ve got a brick or stone house, that will enhance your flowering success, because the stone will radiate heat during winter nights, increasing flower bud survival.

A good friend of mine grows nursery stock and I queried him for advice, too. He recommended caging the plants and filling it with straw mulch (or any loose mulch…not leaves…not hardwood bark) by early December to protect the tender buds. That would not have helped this year, but I may try it in the future.