This popular vegetable can be an ideal perennial denizen of your raised bed garden.
Gardener’s Notebook by Joshua Burman Thayer
Asparagus is a welcome sign of spring on the dinner plate, but it also heralds the year’s coming abundance in your garden. Planting it takes a bit of work at first, and you’ll need some patience to enjoy the results, since you need to wait a year or two before you harvest your first crop. Late winter is the time to plant asparagus here in the Bay Area, so roll up your sleeves and imagine the bountiful times ahead.
Cultivated as a food plant since ancient times, asparagus is a long-lived, deciduous, fern-like perennial. The plants sprout new leaves in spring and grow up to five feet tall. In December, they shed their leaves and stand leafless until the following spring. Left on the ground, the fallen leaves become decaying mulch, which is nature’s way of regenerating the soil.
Asparagus grows wild in maritime habitats but can be cultivated in any garden area where the soil is prepared properly. I grow mine inside a 5- by 10-foot raised bed, which is a perfect spot because it’s a deep and accessible zone of prepared soil that I regularly irrigate and fertilize. As you choose your spot, you might think about where you plan to situate your tomatoes, since tomato and asparagus plants are happy companions: Tomato plants can repel asparagus beetles and asparagus can repel some root nematodes known to impact tomato plants.
How to Plant Asparagus:
- Asparagus plants should be purchased in winter when they are dormant. You can find the bare root crowns stocked at many local nurseries starting mid-January. The crowns should be set two feet apart, so check your intended planting area to see how many plants will fit.
- You will also need some planting mix and some freshwater sand (available at most rock and mulch supply stores).
- Start by digging a trench in your raised bed. It should be one- to two-feet wide and similarly deep. (Now you see why planting it in a raised bed makes sense!)
- Mix part of the soil you dug up with equal parts of the sand and purchased planting mix, and re-fill the trench with this mix. Leave space at the top for compost to be added in the coming months.
- Set each asparagus crown one inch below the soil surface and two feet apart from the next crown.
- Gently water once per week throughout the next month.
- In February, spread a half-bag of compost over the top of your asparagus row.
- In March, spread an additional half-bag of compost.
- Starting in April and through June, you will see spears rise up from each plant. Resist the urge to harvest them the first and second years, since your plants need this time to send down roots and habituate. But in years to come, you will be able to cut and enjoy the spears as they reach a foot or more in height. Do not cut the fern-like leafy branches above the spears, as they are the living asparagus bush.
- In July or August, prune back the extra foliage.
Joshua Burman Thayer’s Gardener’s Notebook is filled with gardening advice for every season. Visit the whole collection of articles here.
Get expert help with your garden from Joshua Burman Thayer at 510.332.2809. Learn more about food forests and permaculture landscape design at nativesungardens.com and from Joshua Burman Thayer’s book, Food Forests for First Timers. Purchase a copy of this book