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Spinach bolts early for various reasons but the good news is you can prevent it next time by identifying and minimizing the cause.
The first few times I grew spinach I wondered why it not only bolted but bolted so early I barely got any to harvest.
Spinach bolts early when stressed by one or more environmental factors. Your spinach is bolting early due to increased day length, heat, cold snaps, lack of water or nutrients, crowding, excessive wind, or pest pressure.
The timing of when you plant certain varieties of spinach may also play a role in early bolting. Maturity is the final reason that causes spinach to bolt, however, this does not cause early bolting.
It’s taken us a couple of years of trial and error to finally get it ‘right’ for growing glorious spinach!
To get to the point where we effortlessly grow it, we considered all the possible reasons for failure. Every time we failed, we recorded what we thought went wrong, and reflected on what we’d do next time to change it.
As time went on, enough changes had occurred, that now we know how to grow the best spinach for our climate!
See: 3 Essentials to Keep a Garden Journal You’ll Use
As you decipher the cause of spinach bolting through this post, I encourage you to record everything you think might be going wrong, and make a plan to implement the needed solutions provided in this article.
Spinach seedlings bolting
Before moving on I’d like to speak to those who are wondering why spinach seedlings are bolting. I’ve been here and understand the frustration, especially when you have a fresh bed with brand-new soil!
Spinach seedlings bolt right away when soil is void of nutrients. Nitrogen-void soil will cause spinach to send up flowers for seed in hopes of reproducing before it dies.
Pests and weeds are likely to be present as well due to the unhealthy state of your spinach. But the root cause of these would ultimately be lack of nutrients.
This happened to us, and I know it’s not because of all the other reasons—it’s just too soon! And our soil test results confirmed it.
Before ordering a large batch of expensive soil for your garden beds, ask to see the results of a recent soil test! You deserve to recieve what’s being advertised.
Onto the solutions!
How to stop & prevent spinach bolting
The big question we all ask at first is if we can stop spinach from bolting once it starts. The reality of this is that you can only prevent spinach from going to seed if it hasn’t already made the decision to do so.
In general, you’ll stop spinach from bolting early by sowing the appropriate variety at the right time of year and providing it with sunlight, nutrient rich soil, adequate space, water, and stable temperatures.
1. Plant a different Spinach variety
If you sowed ‘Winter Giant’ (or any other cold-loving) spinach in the middle of spring, the day length and heat will be quickly on the rise, too quickly for non-bolt-resistant or long-standing spinach. Spinach is a short-day plant so it’s vital to choose varieties that have been grown for withstanding more than desired heat and longer days.
See the succession section of this article for details on when to plant what spinach variety.
The fix for spinach that bolts due to increased day length and hot weather is to jot down when you sowed what variety of spinach, and make a note to plant a ‘long-standing’ (bolt/heat resistant) variety at that time, next time!
Save the heat-intolerant and any non-‘long-standing’ varieties for early spring or late summer to early fall.
2. Plant spinach in optimal sunlight
If you plant spinach in full sun, even during summer, you’ll need to employ tactics that stabilize the temperature, especially for the roots.
If you plant spinach in shade at the wrong time of the year, you might not get much of a harvest and wonder why it never amounted to much before it ultimately bolts upon maturity. Spinach can be shade tolerant, but at the right time of the season.
The fix is to see when and where to plant your spinach: Does Spinach Grow in Shade? When it Does & Doesn’t
If hot sun is the issue, add shredded mulch to the soil, cover with shade cloth, or plant with shade-giving companions (more detail on those in the article above).
3. Provide spinach with nutrient rich soil
Nutrient rich soil will prevent bolting as well as pests and weeds. Nutrient deficiency is often the cause of early bolting when it happens before the plant barely gets started with growing.
To fix nutrient defficient soil either 1) take a sample of soil and get it tested, or 2) add a layer of fresh compost or aged manure and hope for the best.
Add compost or manure to your beds every year to maintain nutrient levels.
Most quality composts and manures contain a balance of essential nutrients that spinach needs.
4. Keep weeds suppressed from spinach plants
Over-crowded spinach can bolt due to lack of resources. If weeds are taking over your spinach it may be lacking in water, sunlight, and nutrients.
To fix an overwhleming mess of weeds, I suggest you ‘reset’ your plot anytime you don’t have a crop actively growing in it.
See how we do it: Best Way to Remove Weeds to Restore Any Garden
5. Keep spinach watered consistently
Inconsistent watering can stress spinach plants into bolting if they dry out too much and too suddenly.
The fix is to either install drip irrigation or adding compost as mulch to ensure spinach has enough water.
Adding irrigation is a temporary bandaid to the underlying problem of soil that dries too quickly. Building up your soil with organic matter is the better way to treat soil that dries fast. Humus rich soil will absorb and retain water rather than allowing excess to run off too soon.
See: When & How to Use Compost as Mulch (For Best Results)
6. Plant spinach during optimal temperatures
In general, spinach is a cool-season crop, meaning it grows best in spring and fall—the cool seasons. Each variety of spinach, however, can withstand various ranges of temperatures.
Refer to the seed packet to see what temperatures each spinach can tolerate.
As a general guideline:
- Spinach seeds germinate best in soils between 50°F (10°C) and 70°F (21°C)
- Most spinach grows the best leaves between 55°F (13°C) and 70°F (21°C)
- Temperatures consistently above 75°F (24°C) or sudden spikes even higher with drops will cause stress and bolting
The fix to maintaining the best temperatures to prevent bolting spinach comes in several forms!
- Have black tarped or bare soil in early spring so it can heat up quickly, and you can sow spinach sooner
- Mulch bare soil with shredded material to reduce fluctuations as temperatures rise
- If mulching isn’t an option, use shade cloth row covers to reduce soil and ambient temperature fluctuations
- Finally, plant the right type of spinach at the right time
7. Sow a variety of successions
Combining successions with the right spinach varieties will go a long way toward expanding your harvest window.
Bolting is inevitably the doom of all spinach! So to maximize our fresh harvesting window, I encourage you to plant several successions of spinach in a single growing season.
Plant 2-4 spinach successions in spring and 2-4 more in fall—each spread a week or so apart.
See: Calculate How Many Spinach Plants Per Person + Successions
What to do with bolted spinach
If your spinach has already bolted and you want to do more than compost it, you have a couple great options!
How to harvest bolted spinach
If bolting has just begun, the spinach probably doesn’t taste too bitter. And if it does, non-picky eaters will still enjoy fine chopped raw or cooked bolted spinach!
Once you harvest all the bolted spinach, reseed the plot or put it to bed with compost and a cover.
Is bolted spinach poisonous?
It’s often said that “you can’t eat bolted spinach” or that it can only be composted. From there, you’re left wondering, why can’t bolted spinach be eaten?
Bolted spinach is not poisonous and is completely edible but less desirable to eat than immature plants. As spinach begins to bolt the vitality is sent to the flower to produce seeds and the foliage becomes increasingly bitter tasting.
Bitter leaves can still be enjoyed raw when chopped up fine or cooked into foods. Cooked spinach ‘melts’ down into practically nothing, anyways!
Taste the spinach raw before throwing it into anything you’re making to ensure you don’t wreck whatever you’re preparing to eat.
How to get seeds from bolted spinach
Bitter bolted spinach isn’t completely useless if you harvest the seeds. Once the plant matures it’ll be brown with noticeable seed pods.
Harvest the plants and hang to dry before stripping the seeds from the stalk. Place seeds in a dry envelope with a label and store in a cool dark place.
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