Best blender for green smoothies: 5 timed on frozen fruit and kale for 50 days

Every blender box in the store says "smooth." My $4 tea strainer disagreed with four of them.

That strainer lived next to my sink in Columbus for 50 days, from August 25 to October 13, while five blenders took turns on the counter: the Vitamix Ascent X2, the Blendtec Classic 575, the KitchenAid K400, the Ninja Detect Duo Power Blender Pro and the Beast Mega 1200. Our kitchen lost most of its counter space and all of its quiet.

I have a five-year-old and a two-year-old, and they judge every drink by one rule. If they can see something green floating in it, it's not happening. So the question for this test was simple. Which blender turns frozen fruit and raw kale into a fully smooth drink in the fewest seconds? Not "pretty smooth." Smooth enough that a kindergartner drinks it before the bus without a negotiation. Here's the winner first, then the long and slightly green story.

How I timed "smooth" with a plate and a strainer

Smooth is a feeling, so I turned it into two checks anyone can repeat at home. First, the recipe. It never changed, and it always went in the same order:

• 1¼ cups cold tap water, always first
• 2 packed cups raw curly kale, torn by hand, stems and center ribs left in (about 2.5 oz)
• half a ripe banana
• 1½ cups frozen mango, pineapple and strawberries, straight from a freezer I kept at 0°F, always on top

That makes about 3 cups, enough for two kid glasses and one for me. The kale stems are the real enemy. A weak blender chops them into tiny green threads that hide in the drink until they land on your tongue.

Every blender ran on its highest manual speed. At 15 seconds, then every 10 seconds after that, I paused the blender and the stopwatch, took a spoonful and smeared it thin on a white dinner plate. No green specks bigger than a poppy seed? Then half a cup went through the tea strainer. If less than a quarter teaspoon of pulp stayed behind, the run passed and the time went on the legal pad on top of my microwave. Two minutes without a pass meant "did not pass."

Each blender got 12 timed runs in the first four weeks, three a week, in a different order every morning so no machine always got the coldest fruit. Weeks five to seven were real life. Each one spent about six days as our only blender for smoothies, soups, pancake batter and one batch of salsa my husband Josh still brings up. Then came a thick frozen test, six runs each. In total: 213 blends and a little over 14 pounds of kale. The rest of our ground rules live on the how we test page. The numbers split the field faster than I expected.

The stopwatch results

Times are the average of 12 standard runs. The thick test was 2 cups of frozen fruit with only ½ cup of almond milk, the kind of blend you eat with a spoon.

An 11-second gap between first and second place doesn't sound like much. At 6:50 a.m. with a bus coming, it's the difference between one try and a second round. Here's why the Vitamix kept winning.

Vitamix Ascent X2: 41 seconds, and nothing in the strainer

The Ascent X2 is the newer, simpler Ascent: a 2.2 horsepower motor on a 120 V base, a 48 oz container, a dial for 10 speeds, pulse, three programs (Smoothies, Frozen Desserts and Soups) and a self-clean program. The base reads which container you put on it, and a low-profile tamper comes in the box.

Its runs ranged from 33 to 49 seconds, and the average was 41. More telling was the strainer. After a Vitamix run I'd tap it on the sink and get a few drops of foam. After the slower blenders I'd get a little green paste.

The reason is the shape of the container. It's wide and low, so the frozen fruit drops straight into the blade instead of building a bridge above it. I watched it on every run. By second 10 the vortex was already pulling kale down from the top.

"That's the first green smoothie that doesn't taste like I mowed something." Josh, blind tasting of all five, September 19

Josh has called my green smoothies "lawn clippings" for years. On September 19 I poured all five into identical cups, numbered the bottoms with a Sharpie and handed them over. He put the Vitamix first and the Ninja pitcher last, and then asked if there was more of number 3. There was not. Ellie drank the whole Vitamix glass before the bus on 11 of 12 test mornings, and the one she skipped was a day she didn't like her socks.

The tamper is what makes it unbeatable in the thick test. With only half a cup of almond milk, two quick pushes got the frozen fruit moving and the bowl was smooth in 52 seconds. The Smoothies program works, but by my plate test it kept going about 15 seconds after the drink was done. I used the dial.

Now the honest part. 48 oz makes about four small glasses. A double batch for a family of four means two rounds. And at about $500 it's a real purchase. The next blender gave me a bigger jar and nearly the same speed, with one annoying habit.

Blendtec Classic 575: fast, until the air pocket shows up

The Blendtec Classic 575 comes with the 90 oz WildSide+ jar, a touch panel with a Smoothie cycle, 60 and 90 second timed buttons, five speeds and pulse. Its blade is blunt and wide, so you can wipe it with a sponge without flinching. Blendtec puts the motor at 3.0 peak horsepower, and it sounds like every bit of it.

On a good morning it was right behind the Vitamix. Ten of its 12 standard runs averaged 47 seconds. On the other two, the frozen fruit formed a dome above the blade with a pocket of air underneath, and the blade spun in nothing. I had to stop, shake the jar and restart, which pushed those runs to 71 and 78 seconds. That's how it lands at 52.

In the thick test the air pocket showed up on 5 of 6 runs. The 575 has no tamper in the box. Blendtec sells a separate Twister jar with a lid that scrapes the sides, and if you love smoothie bowls you'll want it. For drinks with a normal amount of liquid, the problem mostly disappears.

The good part is the size. The WildSide+ jar made a double batch for all four of us plus Walt, our neighbor, who wandered over on day 23 and asked if I'd opened a juice bar. It was also the easiest to clean: wide opening, blunt blade, and the clean cycle with warm water and a drop of soap did the job nearly every time. The warranty is 8 years. It was also the loudest blender of the five, which I'll get to. First, the one that matched my mixer.

KitchenAid K400: slower, steady, and red

I'll admit it. I asked for the KitchenAid K400 in Passion Red because it matches the stand mixer from my KitchenAid Artisan review. Vanity aside, it's a solid machine: a 1.5 peak horsepower motor, a 56 oz ribbed jar, a speed dial with pulse and a few presets, a soft start that keeps the lid from jumping, and a tamper.

It never failed the test. All 12 runs passed, with an average of 1 minute 14 seconds. It simply needs more time to grind the stems down. At 45 seconds the plate still showed a fine green dust. At 70 seconds it was gone. The thick test passed 6 of 6 with the tamper, at 1 minute 31 seconds on average.

It was also the quietest of the three full-size blenders at 90 dB. The downside is cleaning. The blade is fixed in the jar, and kale strands like to wrap around the base of it. A bottle brush fixed that, but it's one more thing to do at 7 a.m. If you want a real blender on the counter for $230 to $300 and you can spare 30 extra seconds, this is a good one. The next blender is cheaper still, and it's really two blenders.

Ninja Detect Duo: a great cup and a weaker pitcher

The Ninja Detect Duo Power Blender Pro has an 1800 peak watt base, a 72 oz pitcher with a tall stacked blade, and two 24 oz single-serve cups with their own blade. Ninja's BlendSense picks the speed and the time on its own, and the dial counts down so you know when it's done. There are also 10 manual speeds if you'd rather drive.

The pitcher was the weakest result of the test. The stacked blade chops fast, so after 30 seconds the drink looked great. The plate disagreed. Fine green threads from the stems were still there at 2 minutes on 9 of 12 runs, and Josh put it last in the blind tasting. BlendSense usually stopped earlier than my plate test would have.

The cup is a different story. Half my recipe in a 24 oz cup passed every time, in 58 seconds on average. The blade sits close to the food in a narrow cup, and there's nowhere for the kale to hide. Then you twist on a lid and walk out the door. For a single green smoothie on a weekday, that's honestly a great setup for $140 to $180. Even in the thick test the cup got 4 of 6 bowls smooth before I had to add milk.

Two notes. That stacked blade is sharp, so I used a dish brush on it and never a sponge. And Ninja says not to blend hot ingredients in it, so soup only went in cooled. The Beast is the other single-serve fan in the group, and the prettiest thing on my counter.

Beast Mega 1200: the pretty one for a party of one

The Beast Mega 1200 looks more like a fancy water bottle than a blender. Walt actually asked if it was a vase. It has a 1200 watt motor, a tall ribbed 40 oz vessel and one button. Press it, and it runs a one-minute cycle that blends, pauses and blends again so everything can fall back into the blade.

With my full recipe the vessel was nearly full, and that hurt it. It needed a second cycle on 9 of 12 runs, for an average of 1 minute 51 seconds, and one run still had flecks after two cycles. With half the recipe it was a different blender: 10 of 12 runs were fully smooth after a single 60-second cycle.

The thick test was the Beast's worst moment. With only half a cup of liquid it stalled on all six runs until I added more milk. It also can't blend hot ingredients. The good news: at 86 dB it was the quietest blender of the five, everything but the base goes in the dishwasher, and it fits under even the low cabinets in our kitchen. It's a very nice blender for one person and one drink. Which brings me to the evenings, and the noise.

Soup night, and the 96-decibel lesson

The test was about smoothies, but nobody buys a $500 blender for one drink. So every blender also made soup. The Vitamix took 3 cups of room-temperature tomato and roasted red pepper base to 158°F in 6 minutes 10 seconds on high, from blade friction alone. Ellie called it "soup that cooked in a tornado." The Blendtec needed four rounds of its 90-second cycle to reach 147°F. The KitchenAid made butternut squash soup silky in 45 seconds, but I cooked it on the stove first and let it cool for 10 minutes. The Ninja and the Beast got cooled soup only, and the Ninja pitcher left it a little grainy.

I learned the noise lesson on day 30. My two-year-old naps from about 1 to 3, and at 1:40 I decided to "quickly" run a Blendtec batch for the soup freezer. Forty seconds. That's all it took. He was awake, I was on the couch rocking a very offended toddler, and the soup sat in the jar until dinner. If your house has a sleeper, plan your blending. Now, which blender should be yours?

Which blender fits your kitchen

If you'd rather have a machine that blends and cooks in one bowl, my Thermomix TM7 review is the other end of this conversation. If you're sticking with a blender, here's what to pay.

Prices, stores and holiday deals

Blenders go on sale a lot between Black Friday and New Year's, especially the Ninja and the KitchenAid. These are the prices we saw at the time of writing and the price I'd wait for:

• Vitamix Ascent X2: about $500 to $550 at Best Buy, Target and vitamix.com. Good under $450. Vitamix also sells certified reconditioned blenders with a shorter warranty.
• Blendtec Classic 575: about $400 to $500 depending on the jar bundle, at Amazon, Walmart and blendtec.com. Good under $350.
• KitchenAid K400: about $230 to $300 at Target, Walmart and kitchenaid.com, with color changing the price. Good under $200.
• Ninja Detect Duo Power Blender Pro: about $140 to $180 at Target, Walmart, Best Buy and Home Depot. Good under $120.
• Beast Mega 1200: about $165 to $185 at Target and thebeast.com. Good under $150.

So where are they now? The Vitamix stays on my counter, and the strainer finally went back in the drawer. The K400 went to my mom, who says it matches "her" mixer. Next on my list are countertop ice cream makers, and you can watch that one on our tests in progress page. More of our kitchen reviews live in the home and kitchen section.

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