Asparagus is one of the healthy and tasty plants to grow in the garden. Another reason to grow them is they can be expensive when bought at a store. But if you’re not careful growing them, the asparagus can start curling.

Your asparagus is curling because insect larvae are feeding on it. The curling may also occur due to underwatering causing the plant to conserve water. Too much sunlight will cause them to curl. Even a lack of nutrients may be the cause.

Attack by pests

One of the most common problems that can cause the asparagus to curl is an infestation of pests. Some such pests include Asparagus beetle, Asparagus aphid, cutworms, Asparagus miner, and Beet armyworm.

Ants farming aphids on my pepper plants
Ants farming aphids on my pepper plants

These pests may attack the leaves, crown, roots, bud, or stem of the plant causing a lack of nutrients.

You need to figure out which pest is attacking your asparagus and take action accordingly. Some of the solutions include spraying water, inviting beneficial insects, using nematodes, growing plants that repel insects, and using organic pesticides.

Infection of diseases

Another issue that can cause your asparagus to curl is an infection of fungal, bacterial, or viral diseases. Some of the diseases that can attack an asparagus plant include crown rot, Fusarium wilt, purple spot, rust, and Asparagus virus.

You can avoid fungal diseases by keeping the asparagus plant well aerated and free from moisture. When watering the plant, make sure not to splash water on the foliage. If you do get a fungal disease, you can try to cut off that part of the plant.

To prevent some of the bacterial and viral diseases, you can try to grow varieties that are resistant to them. Some of the diseases are carried by insects. So preventing them would also help prevent diseases.

Once the asparagus plant has been infected by bacterial or viral diseases, you won’t be able to do much as there’s no treatment for them.

Transplant shock

If your growing season is short or you just want to give more care to the asparagus, you may start the plant indoors. It’s a slow-growing plant and you need to start 12-14 weeks before you can transplant them outdoors.

Once the plant has developed into a seedling, you can transplant it outdoors. But if the plant is not hardened enough, it may suffer a transplant shock. This will stunt the growth of the plant and the asparagus that becomes ready for harvest may end up curling.

It’s good to harden the plant before transplanting it outdoors. You can keep the seedling outdoors 3-4 hours for the first couple of days. You can then keep the seedling outdoors for 5-6 hours for the next few days. And then you can keep it out for the full-sun duration of 6-8 hours for 2-3 days.

Once the seedling has hardened, you can transplant it in your garden or container outdoors.

Crown damage

Crown damage is something that can happen when you’re transplanting the asparagus from an indoor tray to the outdoor garden. And the result will be that the asparagus is curled up when growing.

You need to be very careful and gentle when transplanting the asparagus from the seed tray to the soil. Use your hands to give some support to the crown and roots during the transplant.

Overwatering and underwatering

The most common mistake that beginners make when growing asparagus is to give it too much or too little water and both can be a problem.

If the roots don’t get enough moisture, they won’t be able to supply the required nutrients to the plant. The plant will be unable to create its food. And the asparagus will end up curling as a result when ready for harvest.

If you overwater the roots of the plant, there is a high chance of causing root rot. This means the roots cannot function and provide the required nutrients to the plant. And so the asparagus will curl at harvest time.

I suggest checking the moisture in the soil every day as a start. Stick your finger 1-2 inches in the soil and check if the tip of your finger feels moist. If it does not, that’s an indication to water the asparagus.

Lack of sunlight

Asparagus needs full-sun so it can grow well. This means at least 6-8 hours of sunlight every day. If the plant does not get the required sunlight, the asparagus may curl as it cannot produce the required food.

I recommend planting the asparagus in a location that is not shaded by some obstruction like a wall, fence, tree, or taller plants. If you are growing them in a container, you can just move it to a location that gets good sunlight.

Too much heat

You plant asparagus at the beginning of summer when the roots and crown can grow healthy and strong. The plant needs temperatures in the range of 70 to 85 degrees to grow well.

But if the temperature goes beyond this limit, the asparagus will not be able to bear it and end up curling.

You need to check the average summer temperatures in your area if you want to grow asparagus through the year and ready for harvest by next spring. If you’re growing them in a container, you may be able to bring them indoors if the temperature goes too high.

Lack of nutrients

You will plant the asparagus in summer where it needs to grow strong and healthy roots and crown so it can be ready for harvest early next spring. If the asparagus cannot find the required nutrients, they will curl up at harvest.

I would recommend adding a good organic fertilizer when growing the asparagus. This could be a mix of cottonseed meal, bone meal, and blood meal. If you can get some organic compost, that would also be a good addition to the soil.

Fertilizer burn

Your asparagus plants need good fertilizer when growing them in the summer. But too much fertilizer can also be a bad thing.

A lot of nitrogen will burn the roots of the plant causing a lack of nutrients reaching the plant. This will make your asparagus curl up when it grows for harvest.

You should be careful to follow the instructions provided by the manufacturer when using fertilizer especially a chemical one. Slow-release fertilizer should only be used 2-3 times during the growing season. If you’re using liquid fertilizer, you should use it only once every 2 weeks.

Poor soil

You need to use rich, nutrient soil that drains well when you want to grow asparagus. If the soil quality is poor with too much sand or clay, it will either retain too much water or drain out fast. A lack of good quality soil will cause your asparagus to curl up.

I would suggest performing a soil test for your garden soil before trying to grow asparagus. If it’s not suitable you need to amend the soil with organic compost and amendments.

The other option is to either grow the asparagus in a raised bed created with good soil. Or to grow them in a container with good, quality potting soil.

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