When To Plant Rhubarb Outside

The best time to plant rhubarb outside is in early spring, as soon as the soil is workable and the ground has thawed.
 
This timing is crucial because rhubarb is a hardy perennial that actually thrives in cooler temperatures, and getting it in the ground at the right moment sets the stage for years of harvests.
 
You can also plant rhubarb outside in the fall, but spring planting is generally preferred by most gardeners because it gives the roots a full growing season to establish before winter sets in.
 
In this post, we’ll dig into when to plant rhubarb outside, the specific conditions that make certain times better than others, and how to nail the timing for your specific climate zone.
 
Let’s get your rhubarb off to the best possible start.
 

When to Plant Rhubarb Outside: The Ideal Window

When to plant rhubarb outside really boils down to a simple rule: aim for early spring, roughly two to four weeks before your last expected frost date.
 
That might sound a bit scary if you’re used to waiting for warm weather, but rhubarb is different from most garden crops.
 
It actually needs a period of cold dormancy to grow well, and the young crowns are tough enough to handle a light frost without any trouble.
 
So if you’re asking when to plant rhubarb outside, the short answer is: as early in the spring as you can get your hands in the soil.
 

1. Soil Temperature Matters More Than Air Temperature

When to plant rhubarb outside isn’t determined by how warm the days feel, but rather by the temperature of the soil itself.
 
Rhubarb crowns will start to push out roots once the soil temperature reaches about 40°F (4°C), even if there’s still snow melting in the shade.
 
If the soil is too cold and frozen solid, you obviously can’t dig, so wait until it thaws enough to be crumbly and workable.
 
If the soil is too warm, say above 75°F (24°C), the crowns may struggle and rot before they can establish.
 
So the sweet spot for when to plant rhubarb outside is when soil temps are between 40°F and 50°F, which typically happens in early spring.
 

2. Your Growing Zone Shifts the Calendar

The exact date for when to plant rhubarb outside changes depending on where you live, and that’s totally normal.
 
In northern zones (USDA zones 3 through 5), you might plant rhubarb outside as early as late March or early April.
 
In milder zones (6 and 7), aim for late February or early March, because the soil warms up sooner there.
 
In very warm zones (8 and above), rhubarb is tricky since it needs winter chill, so your best bet is to plant rhubarb outside in late fall for a winter crop, treating it as an annual.
 
Check your local frost dates and soil conditions to dial in the perfect window for your yard.
 

3. Fall Planting Is a Solid Second Option

If you miss the spring window, you can plant rhubarb outside in the fall, about six weeks before the ground freezes.
 
Fall planting works well because the cool, moist soil encourages root growth without the stress of summer heat.
 
Just make sure the crowns are well mulched after planting to protect them from harsh winter freezes and heaving.
 
Many gardeners prefer fall, but spring is still the most reliable time for when to plant rhubarb outside, especially for beginners.
 

How to Plant Rhubarb Outside for Success

Knowing when to plant rhubarb outside is only half the battle, you also need to get the planting itself right.
 
Here’s how to set your rhubarb up for a long, productive life.
 

1. Choose a Sunny, Well-Drained Spot

Rhubarb loves full sun, so pick a spot that gets at least six hours of direct sunlight each day.
 
Good drainage is non-negotiable because rhubarb crowns will rot in soggy, waterlogged soil.
 
If your soil is heavy clay, amend it with compost or plant rhubarb in raised beds to improve drainage.
 

2. Dig Generous Holes and Space Them Out

When you plant rhubarb outside, dig holes that are about twice as wide as the root system and just deep enough so the crown sits at soil level.
 
Space each plant at least three feet apart, because rhubarb is a big, sprawling plant that will spread over time.
 
Crowded rhubarb produces thin, weak stalks, so give it plenty of room to breathe.
 

3. Water Deeply and Mulch Well

After planting, water your rhubarb deeply to settle the soil around the roots.
 
Then add a two-inch layer of organic mulch, like straw or shredded leaves, to retain moisture and keep weeds down.
 
Keep the soil consistently moist but never soggy during the first growing season.
 

Common Mistakes to Avoid When Timing Your Planting

Even if you know when to plant rhubarb outside, a few common slip-ups can ruin your efforts.
 

1. Planting Too Late in Spring

If you wait until late May or June to plant rhubarb outside, the heat can stress the young crowns and stunt their growth.
 
This often results in a plant that produces only skinny, tough stalks for the first year.
 
Remember, rhubarb prefers cool weather, so don’t treat it like a summer vegetable.
 

2. Not Allowing for Establishment Time

You shouldn’t harvest any rhubarb stalks during the first year after planting.
 
Yes, it’s tempting, but the plant needs all its energy to build a strong root system.
 
If you pick stalks too soon, you’ll weaken the rhubarb and reduce future yields.
 
Wait until the second year to start harvesting, and even then, take only a few stalks per plant.
 

3. Ignoring Your Local Microclimate

Your garden’s microclimate can shift the ideal time to plant rhubarb outside by a couple of weeks.
 
A sheltered spot near a south-facing wall will warm up faster than an exposed, windy area.
 
A spot that stays shaded and damp might hold cold soil longer, so adjust your planting date accordingly.
 
Watch your own soil and weather patterns rather than relying only on a calendar.
 

So, When to Plant Rhubarb Outside?

The best time to plant rhubarb outside is in early spring, as soon as the soil is workable and the ground has thawed.
 
You can plant rhubarb outside a few weeks before your last frost date, and the crowns will handle the cold without issue.
 
Fall planting is also possible if you miss the spring window, but early spring remains the most reliable choice for most gardeners.
 
Now that you know when to plant rhubarb outside, you can confidently get those crowns in the ground and look forward to delicious pies and jams for years to come.
 
Happy planting!