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How Tall Can Asparagus Grow: Everything You Need to Know

How Tall Can Asparagus Grow Everything You Need to Know

Not everyone’s a big fan of these green spears, but those who know how to enjoy them really love their nutty, earthy sweetness. And naturally, the fans would want to know how tall can asparagus grow.

Asparagus can grow as tall as 7 feet, especially the larger varieties grown in optimal conditions. When it comes to enjoying their spears, it’s best to harvest them when they’re between 6 to 10 inches tall before they take on a fern-like appearance. 

Above ground, an asparagus plant typically spreads out to 2 to 3 feet. As for the crown and root system, it can extend up to 6 feet in diameter and go as deep as 15 feet.

To understand how big asparagus plants get, let’s explore how the actual plant grows.

Height and Size Potential of Asparagus Plants

Height and Size Potential of Asparagus Plants
Image by Nature of Home
Growth StageAverage HeightAverage WidthAverage Spread
Seedling Stage6 to 12 inchesN/AN/A
Juvenile Stage12 to 18 inches8 to 12 inchesN/A
Mature Growth4 to 5 feet2 to 3 feetN/A
Harvest-Ready SpearsVariesVariesVaries

Asparagus doesn’t shoot up overnight as it goes through distinct phases from seed to harvest-ready spears. These encompass the germination, the seedling, the juvenile, the mature, and the harvest stage.


An asparagus plant starts as a tiny seed, absorbing moisture, swelling, and sprouting. At this stage, it’s just a small seedling emerging from the soil.

Seedling Stage

Once it enters the seedling stage, the asparagus develops its first leaves and gains a bit of height. Seedlings are pretty delicate at this point and need protection from weather and pests, but you’ll see visible growth compared to the germination stage.

Juvenile Stage

In this stage, the asparagus focuses on leaf and root development by growing taller and wider. Typical height is about 12 to 18 inches in the first year or two.

Mature Growth

Asparagus plants experience their most important growth during the third year by reaching heights of 4 to 5 feet and spreading 2 to 3 feet. Take note that the size and length are also influenced by factors like variety and climate.

Harvest-Ready Spears

Once the asparagus enters its mature stage, the focus shifts from stalk to developing edible spears which are usually harvested when they’re 6 to 10 inches long. After harvest, they grow into tall, fern-like foliage.

How long does it take for asparagus to fully grow?

How long does it take for asparagus to fully grow
Image by A-Z Animals

Asparagus typically takes about 2 to 3 years to reach full maturity and produce a good harvest. During the first year after planting, it’s best not to harvest so that the plants establish a strong root system. 

In the second and third years, you can start harvesting but do so selectively to ensure the continued development of the plant. Once mature, asparagus can be harvested for about 6 to 8 weeks each spring, depending on climate and local growing conditions.

How much space does one asparagus plant need?

How much space does one asparagus plant need
Image by Gardeners World

Asparagus needs to be spaced around 18 inches apart, but if you have bigger varieties, you can adjust accordingly. The rows should also be 5 feet apart. 

When planting asparagus crowns, spread out the roots in the trench without compressing or breaking them. Cover the crowns with 2 inches of soil. 

Gradually add more soil as the plant grows so that you end up with crowns about 6 inches below the soil surface.

Do asparagus plants multiply and spread? 

Do asparagus plants multiply and spread
Image by Positive Bloom

Asparagus plants multiply and spread by division and seed. Their crown and root systems grow extensively over time, particularly in the first few years as the plant matures. 

This is why they require ample spacing to prevent their roots from getting tangled. To propagate asparagus plants, you should wait until fall, once the ferns have withered. 

Then, carefully dig up the roots and divide the plant into several sections, each containing a portion of the root system. Replant these sections in different areas without damaging the roots as doing so could cause transplant shock or plant loss.

Another way asparagus can multiply and spread is through its seeds, found in small red seed pods or “berries.” Female asparagus plants produce these berries once they have grown tall and spread out.

Is asparagus hard to grow?

Is asparagus hard to grow
Image by Kellogg Garden Products

Asparagus can be challenging to grow for some homeowners. This is because the plant requires well-drained soil with a slightly acidic to neutral pH, which not all gardens have. 

It also takes a few years for asparagus plants to establish before harvesting. During this time, homeowners need to provide the right amount of sunlight as well as prevent weeds from sprouting to ensure a successful harvest.

When to Harvest Asparagus

When to Harvest Asparagus
Image by AZ Animals

When it comes to harvesting asparagus, pick spears that are 6 to 10 inches tall and around half an inch thick. You’ll likely need to harvest every 1 to 3 days during the asparagus season. 

On average, this means you’ll be plucking spears regularly, depending on their growth rate. More or less, you can anticipate a yield of 3 to 4 pounds of asparagus for every 10 feet of asparagus plants.

When harvesting, snap off the spears just below the soil level, or you can use a knife if necessary. Make sure that the harvested asparagus is stored in a cool place and consumed right away since they don’t stay fresh for long.

In terms of harvesting frequency, you need to be moderate and conservative. If you wait too long to harvest, the spears become tough and difficult to eat. 

On the other hand, excessive harvesting in a single year can lead to reduced growth and lower yields in the next year, particularly for young asparagus plants. It’s best to hold off on harvesting until the third year after planting. 

During the initial two years, the focus should be on building up energy reserves in the plant’s roots.

Why are my asparagus spears so skinny & thin?

Why are my asparagus spears so skinny & thin
Image by Gardener’s Path

Your asparagus spears might be thin due to immaturity, overharvesting, early pruning, depleted energy reserves, and poor growing conditions. Let’s check each one out quickly.


You get thin asparagus spears when the plant is still too young. This happens in the first two years after planting seeds or the first year after transplanting crowns.


When a plant is exhausted from last year’s harvest, it produces fewer and thinner spears. This is especially prevalent in younger plants.

Early Pruning

If last year’s ferns didn’t have a chance to grow and store energy in the roots, it can result in thin spears. This often occurs when ferns are pruned too early.

Depleted Energy Reserves

Thin spears typically appear later in the season for older plants after they’ve used up some of their energy.

Poor Growing Conditions

Environmental factors like insufficient water, sunlight, nutrients, or poor soil quality, also contribute to spindly and thin asparagus spears.

Why are my asparagus spears so thick?

Why are my asparagus spears so thick
Image by Gracious Vegan

There are 2 reasons why you have thick asparagus spears: having male plants and harvesting spears early in the season.

Male plants produce thicker spears because they don’t need to make seeds. As a result, they put more energy into spears.

Asparagus spears are also thicker early in the season, especially during the first few harvests. As the season progresses, the spears become thinner, which is also natural.

Factors Affecting Asparagus Plant Size

Factors Affecting Asparagus Plant Size
Image by The Spruce

It’s not just about planting the asparagus into the soil and leaving them there. Several factors affect the size of your asparagus plants and understanding these factors can help you maximize their growth and overall health. 


Some asparagus varieties grow taller and wider, while others are more compact. Think about your garden space and spear size preferences when choosing a variety that you want to grow.

Soil Quality

Asparagus plants grow very well in well-draining, fertile soil with a slightly acidic to neutral pH. Make sure to give them rich, nutrient-filled soil to encourage larger, healthier plants.


Asparagus plants need at least 6 to 8 hours of direct sun daily if you want the spears to be firm, strong, and tasty. Lack of the right amount of sunlight can lead to smaller plants and fewer spears.


Image by Old Word Garden Farms

The asparagus plant requires regular watering during the growing season. Overwatering can cause root rot while underwatering stunts growth.

When watering, make sure that you give your asparagus plant the right amount. This is especially tricky for sandy soil since it drains quickly and doesn’t retain water well.

Asparagus plants won’t display drought stress symptoms, so soil monitoring and consistent watering are even more important. You can help out the soil moisture though.

Applying some mulch on the soil’s surface helps preserve moisture, especially during hot, dry spells. But if you’re not sure about how to check the soil moisture, we’ve got that covered too.

A practical way to determine when to water is by feeling the soil with your fingers. If the soil is dry 2 or 3 inches below the surface, it’s time to water. 

If otherwise, wait. When watering, we recommend doing so during the morning instead of at nighttime as it allows the water to penetrate the soil and reduce evaporation.

Soil Nutrition

Soil Nutrition
Image by Good Housekeeping

Asparagus plants need plenty of nutrients, especially nitrogen. You can keep enriching the soil with compost or balanced fertilizers.

Layer about 2 to 4 inches of compost into your soil before planting asparagus has multiple benefits. It enhances drainage for clay soil, boosts water retention for sandy soil, and enriches your garden with nutrients.

Compost is a great way to enrich your soil and repurpose kitchen scraps and yard waste. The added bonus is that you can create your compost at home using these materials.

We recommend applying a balanced 10-10-10 fertilizer or about 1 to 1.5 pounds per 100 square feet. We don’t particularly recommend using fresh manure or high-nitrogen fertilizers as they may harm your plants. 

Once you’ve added compost and fertilizer, lay on about 2 to 4 inches of mulch to the soil’s surface. Mulch is known for retaining soil moisture and providing good soil insulation against excessive heat.

Temperature and Climate

Temperature and Climate
Image by Bulbs Direct
Temperature RangeFahrenheit (F)
Minimum50 F
Maximum95 F
Optimal Range65 to 85 F

The asparagus grows really well in temperate regions, so think about your local climate. Remember, extreme heat or cold can affect the size and health of your plant.

Asparagus seeds need a minimum soil temperature of 50 F to sprout. Lower temperatures result in poor germination rates, that is if the seeds even sprout at all.

On the flip side, the maximum temperature for successful asparagus seed germination is 95 F. Beyond this, germination rates start to decline. 

Just know that high temperatures combined with humidity can lead to mold growth. And mold can be quite devastating to your asparagus seedlings.

If there’s anything you need to remember during the growing season, it’s this: the best growing condition for your asparagus is a soil temperature between 65 and 85 F.

Remember that these temperature guidelines apply to soil and not the air. You can use a probe-type thermometer to measure soil temperature. 

We recommend planting asparagus in early spring once the soil is workable after thawing. For transplanting asparagus plants, it’s best to do this 12 weeks after seeding them.

When transplanting established asparagus crowns, early spring is best as they’re still dormant. To avoid planting too early, check the last spring frost date for your area.

Now, if the temperature is too low, you have options. You can wait for the sun to warm the soil. 

To make the soil warm faster, clear the debris from the soil’s surface and choose a sunny location. Use your soil thermometer to monitor the temperature.

When it comes to extending the growing season, use a cloche, a plastic or glass cover. These tools trap heat and warm the air and soil around your asparagus seeds. 

For example, you can make a simple DIY cloche from a plastic water bottle. Just cut off the bottom and place it over your seedbed.


Image by HGTV

When it comes to pruning asparagus, don’t trim the ferns immediately after the harvest. Wait until the end of the season when the ferns have completely withered and turned yellow or brown. 

Allow the asparagus ferns to grow post-harvest. This allows them to store energy in the roots for spear production in the following year. 

During the fall, the ferns bring nutrients and carbohydrates down to the asparagus crown. Trimming them too early can deprive the crown of these nutrients.

Pruning too early also leads to thin asparagus spears in the next growing season. While they might be edible, they’re not exactly what we’re really hoping for.

Pest and Disease Management

Pests and diseases can keep your asparagus from growing healthy and strong. Check for issues regularly and take proactive management of the issues to keep your plants productive.

Varieties of Asparagus and Their Sizes

Varieties of Asparagus and Their Sizes
Image by Fine Dining Lovers

Asparagus plants come in various sizes, and the choice depends on your gardening preferences. We’ve listed some that are popular and pretty easy to grow.

Mary Washington

Mary Washington
Image by Tasting Table
Ease of GrowthModerate ●●○○○
Height3 to 4 feet
Spread1.5 to 2 feet

Named after Mary Washington, George Washington’s mother, this asparagus has historical significance. It has an earthy, nutty taste with a subtle sweetness, which complements various dishes.

This asparagus prefers well-drained soil with plenty of sunlight, either in full sun or partial shade. Keep the soil adequately moist, but avoid waterlogging, and provide support for the plants as they can get top-heavy.

It’s popular among gardeners for its moderate size, suitable for smaller spaces. It’s also a classic choice for gardeners and home chefs.

Purple Passion

Purple Passion
Image by Organic Heirloom Gardens
Ease of GrowthModerate ●●○○○
Height3 to 4 feet
Spread1.5 to 2 feet

The Purple Passion asparagus offers a colorful and tasty alternative to green asparagus. Its purple spears enhance both your garden and culinary creations. 

This asparagus has a distinct sweet and nutty taste. Its purple spears add color and a slightly sweeter flavor to dishes compared to green asparagus.

These asparagus thrive in well-drained soil with plenty of sunlight, preferably full sun. They need proper watering but should avoid waterlogged conditions though they also need some support, like Mary Washington varieties.

Jersey Knight

Jersey Knight
Image by Linden Lane Farms
Ease of GrowthModerate ●●○○○
Height4.5 to 5 feet
Spread2 to 2.5 feet

Jersey Knight asparagus has a rich, earthy taste with a touch of sweetness. Its larger spears are great for grilling, roasting, or using in various recipes.

These asparagus plants do well in well-drained soil and need full sun. They need regular but not excessive watering. 

You might have to provide support for the tall, sturdy spears as they grow to prevent bending or breaking. Jersey Knight asparagus is well-known for its prolific, large, tender spears suitable for various cooking methods. 

Connover’s Colossal

Connover's Colossal
Image by eBay
Ease of GrowthModerate ●●○○○
Height4.5 to 5 feet
Spread2 to 2.5 feet

Connover’s Colossal lives up to its name as one of the largest asparagus varieties. It’s beloved by those who enjoy generous-sized asparagus spears. 

This asparagus is celebrated for its robust, earthy flavor. The spears have a thick, meaty texture and an intense, savory taste, making them a popular choice for grilling or roasting.

This asparagus variety thrives in well-drained soil with ample sunlight. Make sure they receive at least 6 to 8 hours of sunlight daily. 

Give good spacing between plants to make sure their substantial spread doesn’t result in overcrowding. This asparagus variety loves deep regular watering to produce its famous large spears.


Image by JBA Seed Potatoes
Ease of GrowthModerate ●●○○○
Height4 to 4.5 feet
Spread2 feet

Gijnlim asparagus is known for its consistent size, making it great for gardeners who want reliability. It works well for both beginners and experts, making it a valuable addition to any asparagus collection.

This asparagus has a delicious taste with mild sweetness and nutty hints. It offers a pleasant earthy touch that’s popular in various dishes, whether wrapped with prosciutto, added to risotto, or grilled with lemon and garlic.

This European asparagus type loves well-drained, loamy soil. It needs a good amount of sunlight but just be cautious about overwatering. 

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