How to harvest asparagus – why you can cut or snap, but never pull this crop

Asparagus is a spring delicacy and the delicious spears are highly prized during the crops’s short harvesting season.

Providing one of the first harvests each year, growing asparagus does need self-restraint, but it is worth it all when the time comes to harvest the spears. But the season is brief and the stems are delicate, so there are wrongs and rights to harvesting asparagus.

I bring experience growing and picking spears from several vegetable gardens and have asked for tips from other experts about when and how to harvest asparagus, so you can enjoy great yields of spears and healthy crowns.

When to start harvesting asparagus

Patience is required when growing asparagus. It can take two years from planting asparagus to get the first harvest - longer if you grow the plants from seed.

From the third spring, you start to harvest and the perennial vegetable plants can provide you with spears every spring for the next 15-20 years. When plants are ready to pick, there is a set window and a proper way to harvest asparagus.

When to harvest asparagus

The asparagus spears will start to appear in spring each year. The window to harvest is only small, lasting around six to eight weeks each spring. It will vary depending on location, but often starts around mid-April and ends in late June.

As the spears emerge from the ground, the sign to keep an eye on is the size of the spear. The height of the asparagus spear is the best indicator of when to harvest.

‘The general rule is to harvest between 6-10 inches tall,’ says Mark V Wessel, director of horticulture research at Gardens Alive! ‘There is leeway on either end of the range. If you need just a few more spears to have enough for a meal, it is no problem to harvest at less than 6" or more than 10".

‘If less than 6" you are depriving yourself of higher yields from that spear getting bigger. More than 10" the spear might be getting ready to fern out and will have a tougher portion towards the ground level.’

As mentioned, the season to harvest asparagus is short. Resist the urge to carry on harvesting past the end of June as continuing to harvest will stress the plant and impact future yields.

Harvesting too long and reducing the amount of energy stored in the crown will affect the size of next year’s spears. This is because, as Dick Zondag, the owner of Jung Seed Company, explains: ‘The diameter of the spear is in relationship to the amount of stored energy in the crown of the root system.’

Once the emergence of stems has slowed down and the width of the spears that appear has reduced to less than that of a pencil, that is the sign to stop picking. After the harvesting season has ended, leave the plants to continue growing and develop into ferns before cutting back asparagus in the fall.

Mark V Wessel

Mark V Wessel is the Director of Horticulture Research and Research Farm Manager at Gardens Alive! - the company that specializes in selling organic garden and lawn supplies

How do you harvest asparagus?

The best way to harvest asparagus is with clean and sharp garden tools, such as pruning shears, a harvesting knife, or a dedicated asparagus knife - a special long and forked tool designed specifically for the task.

The individual asparagus spears want to be harvested an inch below the soil surface, taking care not to damage any other nearby shoots. Cutting below the soil surface means cutting at the more woody base of the spear, which reduces water loss and ensures the asparagus spear stays firm for longer.

Mark V Wessel says he has a ‘knife dedicated to harvesting asparagus’ that is his chosen tool but admits ‘asparagus is very forgiving’ of the method of being harvested.

‘When harvesting, I cut it just below the soil level,’ he adds. ‘If I have forgotten my knife and the asparagus is nice and tender, I will snap it off at ground level.

‘You want to avoid snapping or cutting off above ground level. If too much stalk is left above ground level after harvest, that stalk could continue to grow, and a new stalk may not be initiated into growing as quickly.’

While you can cut or snap the steam, it is not recommended to attempt to pull - that would be a vegetable harvesting mistake that can damage the plant and decrease your yield. Dick Zondag warns: ‘The danger of pulling asparagus spears is if the spears are more fibrous and you pull too hard you may injure the crown by pulling. This is especially dangerous if you plant the roots too shallow.’

Harvesting spears every two or three days through the window will encourage the continual development of lots of shoots and give you the best yield each year.

Dick Zondag

Dick Zondag is the owner of Jung Seed Company, a cherished family enterprise flourishing since 1907. He has a YouTube channel, The Garden Doctor, where he shares tips, tricks and tales from the soil.

FAQs

Does asparagus grow back after you cut it?

Asparagus does not grow back after the stem has been harvested. The underground asparagus crowns will continue to produce new stems throughout the season. New stems will emerge as you regularly harvest throughout the picking window.

How many times can you harvest asparagus?

You can harvest asparagus regularly over the 6-8 week window in spring when stems reach usable size. Picking every two or three days would give you around 20-25 harvests over that period, once the crowns are fully matured. The productivity of the crowns year-to-year will depend on their age, if you fertilize asparagus annually, and the growing conditions each season.

What happens to asparagus if you don't pick it?

If asparagus spears get over 10 inches in height they will start to go fibrous and woody, before developing into asparagus ferns. Remember not to pick asparagus for the first two years after planting, then harvest the delicious spears regularly throughout the small window from year three onwards.

Once you have established crowns in your kitchen garden, there are ways to propagate new ones. It includes growing asparagus from cuttings or dividing crowns in late winter or early spring to get more for your garden. It will take at least a year from dividing an asparagus crown and replanting it to get a harvest from it.