If you are growing asparagus crowns for the first time, then you probably have some questions about when to start harvesting and how to go about it. If you've forgotten everything your grandma taught you, or you were just too young to remember anything past that wonderful taste, we hope this will help.
The very first rule is patience! An asparagus bed, if established and maintained properly, can produce asparagus spears in excess of 15 years. In fact, some asparagus beds have been producing for 30 years! So, the first year you want to avoid harvesting, except maybe to get a very tiny taste of what's to come, and concentrate on growing the healthiest and strongest root system possible.
The First Year
We recommend babying your asparagus through the first year. Invading perennial grasses are young asparagus' worst enemy, so keep them under control as your young plants are becoming established. Depending upon where you are planting, you may want to install a barrier, keeping it in place through the first year, to be removed at a later time if you choose.or not. The root system of asparagus goes deep and becomes quite extensive, but the plants need that first full year to really take hold and to survive the winter, especially in the coldest regions. You should provide 1 to 2-inches of water per week during the first two years and feed well. After the second year, you can water more infrequently. You might want to use a soaker or drip hose through your asparagus bed, rather than watering from the top as this will allow the water to soak deeper, instead of settling on the tops of the plants; there will also be less evaporation, resulting in less water use. Applying mulch around your plants will also conserve water, as well as inhibiting weed and grass growth.
As the spears are left to grow past the point of harvesting, the tops will open up and become fern-like. They are actually quite pretty, but also a very important aspect to the continuing good health of your asparagus bed. Using photosynthesis, these ferny tops will send food throughout the spears and into the crowns below the surface, ensuring the perpetual harvest that this perennial vegetable provides.
When it comes to cutting back your asparagus plants, there are basically two schools of thought. Some gardeners cut them back to the ground once they turn brown, going dormant, usually after the first heavy frost. In fact, some people just mow them down as close to the soil as possible, either adding the foliage to their compost bin or discarding it. The other half of asparagus growers will leave the ferny tops to catch the snow and to protect and insulate the plants, while providing necessary moisture throughout the winter and into early spring. Cut them back in March or early to mid-April, depending upon your climatic zone. Besides helping your plants to survive the winter, the brown, feathery ferns will add a bit of winter-time interest to your stark garden landscape, especially when coated in layers of sparkling hoar frost.
The Second Year
Finally, your patience has paid off! The spears are growing and you can start harvesting, but only for a little bit and only a little at a time. At no time should you harvest spears that are not at least as big around as your little finger. For this second harvest year, we suggest that you only harvest for the first 2 to 3 weeks. Heavy and continual harvesting past this point may weaken the plants, meaning that your asparagus bed will not continue to develop well for subsequent years. Just a little more patience is required. Time flies and a little patience now will reap huge rewards in three, four, five..fifteen or twenty years!
In most areas of the country, you will be able to start harvesting in May and continue into June. Asparagus is considered a cool weather crop and will be one of the first vegetables ready for harvest, even before your lettuce, broccoli and cauliflower. However, in more temperate climates, like that of southern California, you may have to treat your asparagus a bit differently, keeping track of the normal growing cycle for this perennial and allowing the ferny tops to grow and develop, rather than harvesting for an extended period just because you can. And then cut the plants back in late fall or early winter to encourage dormancy that occurs naturally in other climates.
As in all things gardening, gardeners have different ideas on what is the best way to harvest. Some prefer to use their thumb and forefinger to snap the spear at ground level, while others will use a sharp knife or asparagus harvesting tool to cut the spear one or two inches below the soil. It is our belief that using the asparagus knife to cut below the soil allows the plant and crown to be protected by that layer of soil, from both the hotter summer temperatures and marauding pests. A clean, sharp tool will also ensure that the plants are not stressed from the cutting. Pulling and tugging while snapping the spear can result in damage to the crown below the spear, which is already developing new buds for next year's harvest.
Don't forget! Only harvest this second year for 2 to 3 weeks! Your patience will be well-rewarded.
The Third Year and Into the Future
Now that your asparagus bed is well-established, you can harvest spears that are emerging which are 3/8 or larger (about the size of one's little finger). Also, don't submit to the myth that the larger the diameter of the spear, the less tender they are. That is just not the case at all. What IS true, is that as the season progresses, the part of the spear below the ground and possibly 1 or 2-inches up, may become somewhat tougher. This is just a fact of life when it comes to asparagus and one easily remedied by just cutting off the tougher part. You will still have plenty of tender asparagus spear above this point. If you've missed harvesting some spears and the tips are no longer tight and closed, you will be a little disappointed in the quality, so allow those spears to open and become ferny. You won't be wasting them, just allowing them to become next year's harvest.
As a rule, you will harvest every other day when the spears are between 4 and 8-inches tall and usually for a period between 6 and 8 weeks, depending upon your geographical location, and also depending upon the weather for that particular year. Hotter weather will shorten your harvesting season, while cooler weather will extend it.
Again, once you notice that the emerging spears are smaller than your little finger, quit harvesting and allow the ferny tops to develop, effectively perpetuating the cycle that will have your grandchildren and great-grandchildren harvesting the asparagus bed you plant today. Early summer mornings, working by grandma's or grandpa's side, will be a perennial memory!