Stages of Growing Asparagus | Life Cycle

I rarely see asparagus (Asparagus officinalis) growing in other gardeners’ vegetable beds. In reality, though, asparagus is very easy to grow — it even grows wild in many cooler regions! 

The only real downside to growing asparagus at home is that it takes several years to establish before you can enjoy the first harvest. But once this perennial vegetable is well-established, asparagus can continue producing for over a decade.

In this article, I’ll walk you through the stages of growing asparagus and why I think this unique veggie is worth adding to your own home garden.

Conditions for Growing Asparagus

Asparagus is a cool-weather vegetable that grows well in USDA zones 4 to 8. Spears start to grow as soon as the soil temperature rises above 50°F, so it’s usually one of the first crops to emerge in the spring. 

The asparagus harvesting season lasts from late April to June. Cooler climates will experience later harvests on average than warmer climates and vice-versa.

Planting asparagus is an investment due to how long this vegetable is capable of producing. For a consistent harvest, plant 5 to 10 asparagus plants per person in your household. It’s also best to select a spot along the perimeter of your vegetable garden to prevent the root systems from being disturbed year after year.

Asparagus prefers 6 to 8 hours of bright, direct sunlight per day. Plants can reach over 4 feet tall later in the season, so be careful not to shade out other sun-loving crops in the process.

You’ll need loose, well-draining soil to grow happy asparagus. They grow best in a soil pH of about 6.5.

I like to plant asparagus in raised beds because it’s significantly easier to control the soil quality and they don’t need a ton of room to thrive. The ideal depth for planting asparagus is 6 inches, so opt for a 12-inch raised bed for the best results.

According to Iowa State University, a balanced 10-10-10 fertilizer is normally sufficient unless a recent soil test indicates a need for additional phosphorus or potassium. Fertilize just before growth begins in the spring and again, if desired, after the year’s final harvest.

I recommend applying a thick layer of mulch to newly planted asparagus to aid in moisture retention and suppress weeds. Pesky weeds can outcompete with young asparagus, and physically pulling them can disturb the delicate root systems.

Growth Stages Of Asparagus

The edible part of an asparagus plant is a young shoot. When left to grow into summer and fall, this shoot will eventually produce fern-like foliage, flowers, and inedible berries.

You have to wait 2 to 3 years after planting asparagus before any of the spears can be harvested. This gives the plant time to develop a strong root system for winter dormancy and future harvests. 

While it’s possible to grow asparagus from seeds — I’ll cover the seed and seedling growth stages below — most gardeners start this vegetable from ‘crowns’. Crowns are bare root systems that already have a season or so of growth in their metaphorical pockets. 

Growth Stages Of Asparagus
Bareroot asparagus crowns

Starting asparagus from crowns rather than seeds is less labor-intensive and tends to result in an earlier first harvest due to the head start the plants have on growth.

Asparagus is categorized as a dioecious plant. This means that each asparagus plant is either male or female and bears flowers of the same sex as itself. 

In terms of spear development and edibility, sex doesn’t matter. The distinction only matters if you plan to save seeds from your garden. 

With that said, there’s some evidence that male asparagus plants make a better crop because they don’t expend energy on seed production. There are actually several asparagus cultivars available that exclusively grow male plants for this reason. All-male cultivars also do not produce the plant’s toxic berries.

1. Seed Germination 

Asparagus grows from small, round, black seeds that come from the plant’s red berries. In my opinion, seeds aren’t the most efficient way to grow asparagus at home. However, they are very economical and may be the only way to get your hands on unique cultivars.

Asparagus seeds require exposure to light (even if covered by soil), moisture, and warmth to germinate. At temperatures between 70 and 85°F, germination typically occurs within 14 to 21 days. In some cases, though, it takes up to 56 days.

Once germination begins, the seed embryo works to produce several vital structures. These include the:

  • Radicle (primary root)
  • Hypocotyl (primary stem)
  • Cotyledon (embryonic leaf)

While the majority of garden vegetables sprout with two cotyledons, asparagus is classified as a monocot. This means that each seed has only one cotyledon.

When an asparagus seedling emerges from the soil, it looks like a very, very small asparagus spear. The seedling will grow several inches tall and produce many thin leaves in its first year.

Seed Germination

2. Crown Formation

The asparagus crown, or root system, continues developing throughout the plant’s life cycle. While the crown will be relatively small and delicate during the first few years, it can eventually grow up to 5 or 6 feet in diameter. 

A healthy crown is the backbone of a good asparagus harvest. The root system is responsible for storing energy for overwintering and sending out fresh buds each spring.

The reason harvesting young asparagus spears is such a no-no is that doing so can stunt crown development.

3. Spear Emergence

Each spring, new spears will emerge from buds within the asparagus crown. The size and number of spears will increase with each passing year — don’t be alarmed if your asparagus appears very thin at first.

It’s a common joke among gardeners that sprouting asparagus looks like someone stuck a handful of grocery store produce in the dirt. But that’s really how this vegetable grows!

Vigorous asparagus spears may grow up to 2 inches per day. The stalk will start out very soft and green but eventually turn woody at the base. 

4. Ferning Out

What is commonly referred to as ‘ferning out’ is actually just the asparagus plant-producing leaves. This foliage is essential as it allows the plant to photosynthesize at its full potential and store energy for the rest of the year.

Asparagus leaves are called ferns because of their appearance. However, asparagus is not a type of fern nor closely related to true ferns. (To make things even more confusing, though, the ornamental ‘asparagus fern’ is actually a type of asparagus!)

Ferning out normally starts when temperatures rise in early summer. Depending on the maturity of your asparagus plant and your climate, it could take 70 days for spears to fern out after emerging from the soil.

Sometimes, asparagus will fern out earlier than expected. This is colloquially known as the asparagus ‘popping’. It’s similar — but not identical — to the phenomenon of bolting seen in other vegetable crops like broccoli and cabbage.

Popping most often occurs when there are unusually hot temperatures early in the season. It can also be triggered by drought conditions, so adequate water is a must during the spear emergence period.

Flowering

Asparagus plants produce white or yellow flowers shortly after the ferning out process is complete. The flowers are bell-shaped and droop from the ends of thin stems along the length of the main stalk.

While the flowers are only about ¼ inch long, you may be able to distinguish a male plant from a female one by looking closely at the stamens. The stamens of a male flower will appear bright yellow or orange due to the presence of pollen, which is absent from female flowers.

6. Pollination

Insects are responsible for most asparagus pollination. Pollination typically occurs in the early morning when the flowers are fresh.

Since a single asparagus plant will only ever produce male or female flowers, you need at least two plants for pollination. Realistically, though, gardeners interested in saving seeds will need several plants to guarantee seed production.

7. Berry Development

Not all asparagus produces berries. Typically, only female plants are capable of bearing fruit and creating seeds. 

Most asparagus plants produce berries in early fall or about 90 days after ferning out.

Asparagus berries start out green in color but ripen to a very bright red. It’s important to note that berries are toxic to humans and pets and are, therefore, inedible. 

Berry Development
Berries appear on the asparagus plant after ferning out

When To Harvest Asparagus

Most asparagus varieties produce green or purple spears. Spears are usually harvested once they reach 8 to 10 inches tall and are ½ to ¾ inches thick. Some gardeners prefer more tender asparagus and, therefore, harvest a bit earlier.

White asparagus is a popular commodity at some grocers and farmers’ markets. According to Pennsylvania State University, these spears do not come from a unique variety but are instead cultivated by withholding sunlight from the plant as the spears develop.

Since soil temperature dictates when asparagus begins sprouting in the spring, the harvest period varies slightly from one climate to another. On average, however, asparagus reaches a harvestable size starting in late April. 

While new spears will continue to grow, you should stop harvesting by late June or early July. The remaining spears will complete the rest of the asparagus plant’s life cycle and prepare the underground crown for winter dormancy.

Note that the harvesting period for asparagus naturally lengthens as each plant matures. You may only be able to harvest spears from a young plant for 14 days. Meanwhile, a full-grown asparagus plant can produce for up to 60 days per season.

Again, do not harvest spears until the asparagus is at least 3 years old. Harvesting too early in the asparagus life cycle may kill the plant or severely restrict its growth. Some gardeners opt to harvest up to half of the spears that emerge in the second year. For optimal growth in the future, though, I recommend just waiting until the plant’s third season.

If you liked this article, why not take a look at Companion Plants for Asparagus?

FAQ Stages of Growing Asparagus Plants

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.