Learn how to grow asparagus, an easy perennial that will give you early spring harvests. Get my best growing tips, lots of questions answered and see what an asparagus bed looks after it's left to fern out.
Asparagus is really an unusual plant that many people only know about from the bundles of stalks available in the spring in stores.
The stalks we know and love to cook and eat are only one of the first stage of the plants seasonal life cycle, though. Once the season is done and the stalks are allowed to grow, it literally creates a hedge of ferny foliage.
When I showed visitors my garden with the 20-foot beds of asparagus in July or August, the #1 question I got was "What is that?" pointing to the asparagus hedge because hardly anyone knows what asparagus looks like as it grows.
I didn't either before I started growing it - and it is an amazing plant, I think!
Which made me realize that while I have a great Ultimate Asparagus Guide that shares how to grow, harvest, and cook with asparagus, I should share more about growing asparagus, especially what the beds looks like in summer after the asparagus harvest has stopped, as well as answer a few questions I've gotten.
I love growing asparagus and hope you will try it if you haven't.
It's a plant-once-and-forget-it (almost) perennial vegetable. Meaning once established, it will produce for you every year with minimal work.
That's pretty great, isn't it?
How to Grow Asparagus
The #1 thing to know about growing asparagus is that the roots will take a few years to get established.
This means you can't harvest all the shoots you see coming up in the first three years - you have to let them grow and "fern out" to provide food for the next year's larger crop.
Here's a basic establishing-harvesting schedule:
- Year 1: Plant 1 to 2 year old crowns and let all the spears that appear grow.
- Year 2: Add a layer of compost and maybe harvest a hand full of spears (if you have a large enough bed and if the spears are growing well) - err on the side of no harvest if you're in doubt. I've read that a light harvest after the first year may stimulate more bud production, providing greater future yields, as compared with waiting two years before harvesting, but again it's still a very light harvest.
- Year 3: You can harvest about 25% of the spears that appear in the first three weeks, then let them grow.
- Year 4: Harvest the spears for 4 weeks, then let them grow into their fern-like hedge.
- Year 5 and beyond: Increase the harvest by one week each year until you are harvesting a full season, about six to eight weeks.
Your reward for this patience? Many, many years of faithful, strong asparagus production!
Other than knowing how to establish an asparagus bed, growing them is pretty simple.
Steps to Grow Your Own Asparagus
While you'll find these steps covered in the Ultimate Asparagus Guide, I'll briefly list them here with some additional tips.
- Where to Plant: Site the bed in full sun - at least 8 hours a day. This bed will be there for many years, so make sure it isn't near plants that may shade it as they grow or compete for water. Make sure the soil isn't too acidic and that it drains well - you don't want the roots to sit in any pooled water.
- How to Plant: You can plant the crowns 2 to 3 feet apart in a raised bed or just mounded soil, but you have to be able to dig down 18 inches to plant the roots deep and spread them out then mound the soil as they grow the first year. I chose to do this with a raised bed as that was easier with our hard clay soil. TIP: Asparagus roots do not like to compete with weeds or other aggressive roots (think running berry roots), so think about this when planting, This was another reason I went with a raised bed with sides, since it's easier to monitor weeds.
- How to Water: In the first two years you will want to water regularly to supplement any rain so that the newly established roots get 1.5-2 inches of water a week. Older plants need 1 inch of water a week. TIP: I found it easiest to lay soaker hoses that ran weekly to meet this need. You can also automate it as part of your garden watering system, too.
- Maintenance: Besides water, both newly established and older asparagus beds need only a few tasks done - occasionally weed to keep the roots free of competition, top dress with compost (about 1 inch) in the spring each year, and then cut off the brown, dead stalks the next fall to prepare for the new spring harvest. That's it - they are SO easy compared to fussier vegetables!
How to Harvest Asparagus
The above photo is our old asparagus patch in desperate need of harvesting - I hadn't been in the garden for about 3 days, but that's all it takes during harvest season.
Here's what I wish someone had told be about growing asparagus:
Once established, it will grow prolifically and if you want to harvest for the full season, you have to pick it almost daily during the 6-8 week season - and that's a LOT of asparagus, depending on the size of your bed!
So if you can't pick everyday or at least every other day, you'll want to have someone come and harvest for you to be able to keep harvesting or the stalks will all start to turn into fern stage.
As you might imagine, we were all so excited each spring for the first stalks of tender asparagus...and then two months later, we were equally excited to let the stalks grow and move on to other vegetables!
Tips for harvesting Asparagus
- Remove the spears when they are 6-10 inches tall (ideally) and the tips are closed. However, if you can't get out to the garden for a few days and the spears have shot up about a foot (it happens!), you can do what I do - simply snap them and cut the tough bottoms off to make them the length you want.
- To harvest, snap the stalk or use clippers to cut the spear at ground level. I've read various ways to harvest, some calling for cutting at the dirt level, some below, some breaking off at the natural point, others below dirt level in case of fungal growth (but then you can cut a new spear emerging...). TIP: After years of growing, the easiest and most effective is to snap the spears at or slightly below ground level - with clippers I found I would often cut the new emerging growth by accident.
- The first spears will appear when the soil is 40-50 degrees and your harvest will continue depending on the air temperature (so different parts of the country have different lengths of harvest). TIP about late frosts: I've had the first spears appear at the beginning of April followed by a couple of 29 degree lows which frozen them. I simply cut all the mushy frozen ones off, added more compost, and more grew - this is one hardy plant.
- Harvest Timing: In the early cooler part of the season the spears can grow 10 to 12 inches with tight heads and a low amount of fiber in the base of the spears. As the weather warms the spears will “fern-out” at a shorter height and fiber will develop faster so you should harvest the spears shorter during warmer weather until the harvest season ends.
- Cut all the spears during the harvest window, even small ones (you can compost them) to keep the bed growing evenly and to not provide a place for asparagus beetles to lay their eggs.
- When to stop harvesting: as a general rule, you should stop harvesting when the diameter of 75% of the spears becomes less than 3/8 inches. I've found that using a specific number of weeks is easier to calculate for me, which is between 6-8 weeks on older, established beds.
One thing I've learned about growing our own asparagus is that the spears that grow are not uniformly round like the bunches in the store.
You'll get thin ones, normal ones, and really fat ones. And I do mean fat- I've personally never seen asparagus as fat as some I grow. But they still are tender and I've learned to adjust cooking times accordingly.
Also, they don't all start getting thinner toward the end of harvest as I've read.
There are always good sized spears even after six weeks, but I decide to stop harvesting at that point to provide the roots with the food they need to produce well the next season.
The most common pest is the asparagus beetle. basically if you grow asparagus, you will have them. They are orange with black spots or lines with a more elongated body than Asian beetles. If your spears are curved or hooked, the beetle infestation is doing harm.
Monitoring and hand picking the beetles off plants can keep a small population under control. A beetle’s instinct is to drop when it feels disturbed, so hold a pail of water, or even just a box, under the plant before gently shaking it to knock the bugs off.
For bigger infestations try an application of neem oil in combination with cutting just below ground so that asparagus beetles will not use the stub to lay their eggs and multiply.
The best organic control for spotted asparagus beetles is to plant male-only cultivars that do not form berries. If your plants do produce berries, gather and compost all asparagus berries if spotted asparagus beetles have been seen to remove the potential larvae inside the berries.
Growing Asparagus FAQs
Here are a few of the questions I always get from visitors to my garden and readers who've seen photos of my beds:
- How long can you pick asparagus? Asparagus is harvested only for about 6-8 weeks in spring and then you let the spears grow, which produces fern-like growth from the tall stalks. Alternately, to get a fall harvest you can let the spears grow in spring, cut them all down in August and then harvest the spears in September and October.
- Why do you have to stop picking? Harvesting for only a season of time is important to the health and longevity of the plant - letting it grow feeds the roots and creates bigger and stronger plants.
- How hard is it to grow? It takes awhile to grow a decent asparagus patch - you don't really harvest much of anything for the first 2-3 years after planting. But it is a perennial plant that only requires the basic maintenance I've mentioned: keep weed-free, water regularly, feed in spring with a top coating of barnyard compost, and cut down the brown fronds in the fall or winter.
- How much should I plant? The two 20-foot beds with two rows of crowns I planted actually provided too much asparagus for our family of four (with two kids who were only so-so about it). I froze and canned it and found other people to give it to, but I should've planted less. A 10 to 15 food bed is probably fine for a smaller household, depending on the amount of preserving you'd like to do.
- How come the spears are all different sizes in the photos? Like I mentioned I've found that the spears are never all the same size - there will be thick spears and super thin ones from the same root. And from the first month of harvest to the last. So the common instruction to stop harvesting when most of the spears are "smaller than a pencil" doesn't really work for me - I use the 6 weeks rule.
Finally, a reader asked, "Do you grow only asparagus in this bed?"
Which is probably because there seems to be a lot of bare ground in the photos above.
The answer is yes, it's all asparagus (besides a few nasturtium I let reseed at the front of the beds) because:
- The roots of asparagus don't like competition.
- And this is what asparagus looks like in summer:
They grow to a HUGE six-foot tall ferny hedge by the height of the summer!
The nasturtium like it and I allow a few to grow at the front of the beds to provide beauty and bee food, but that's about it.
In spring, I reap baskets like this shown almost weekly (the asparagus more often, of course)- the prolific asparagus with early rhubarb stalks.
Both of these are perennials for the vegetable garden and growing these perennial plants assures that we always have something to harvest in early spring, whether we've planted anything or not.
Do you grow asparagus? What growing tips would you add?
Ready for more information and a TON of recipes for asparagus and rhubarb, two of early spring's easy perennial crops?