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Blue toadflax
Blue toadflax
Blue toadflax
Blue toadflax
Blue toadflax
Blue toadflax
Add to My Garden
Blue toadflax
Nuttallanthus canadensis
Also known as: Old-field toadflax
Blue toadflax grows to 25 to 80 cm tall. It features tall stems and purple to off-white flowers. The blue toadflax flowers from mid-spring to late summer in the Eastern part of North America.
Hardiness Zones
4a to 8a
Hardiness Zones
Weeds
plant_info

More Info

Flower Color
Flower Color
White
Pink
Purple
Blue
Bloom Time
Bloom Time
Spring, Summer, Fall
Leaf Color
Leaf Color
Green

Name story

Blue toadflax
Blue toadflax is sometimes still called Linaria canadensis although in 1988 it was reclassified as Nuttallanthus canadensis.
The new name honors Thomas Nuttall, a British naturalist and plant collector. Anthos is Greek for flower.

Symbolism

Protection, Hex breaking
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weed

Weed Control

Weeds
Blue toadflax is a weed that is native to eastern North America from Ontario to Nova Scotia, south to Texas and Florida, and west to Minnesota, Oregon, Texas, and California. It is commonly found growing along roadsides and in fields, where it becomes noticeably weedy. The only country of the world where blue toadflax is considered invasive is Brazil. Exercise caution as parts of this plant are poisonous if ingested. To control spread, the normal methods for removal would be pulling the weeds out by hand to include the roots system or use of an herbicide.
How to Control it
If unwanted, blue toadflax can be physically removed. Once it starts to flower it can be more difficult to remove, so it is best to deal with it early to prevent spreading. Start by pulling out the blue toadflax as much as possible. It should come out easily as it does not have very deep roots. Collect all parts of the plant and dispose of it appropriately. If the blue toadflax regrows by itself after a period of a few weeks, pull again and apply a chemical weed killer to the affected area, being careful not to spray other plants.
weed
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distribution

Distribution Map

Habitat

Bare areas and grassland
distribution map
Native
Cultivated
Invasive
Potentially invasive
Exotic
No species reported
habit
question

Questions About Blue toadflax

Watering Watering Watering
Sunlight Sunlight Sunlight
Temperature Temperature Temperature
What is the best way to water my Blue toadflax?
To water Blue toadflax, you can use a garden hose with a spray nozzle, a watering can, or just about any other common watering tool. Generally, Blue toadflax is not too picky about how they receive their water, as they can live off of rainwater, tap water, or filtered water. Often, you should try not to water this plant from overhead, as doing so can damage the leaves and flowers and may lead to disease as well. At times, the best method for watering this plant is to set up a drip irrigation system. These systems work well for Blue toadflax as they apply water evenly and directly to the soil. For one Blue toadflax that grows in a container, you can use a similar watering approach while changing the tools you use. To water a container-grown Blue toadflax, use a cup, watering can, or your tap to apply water directly to the soil.
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What should I do if I water my Blue toadflax too much or too little?
The remedy for underwatering Blue toadflax is somewhat obvious. When you notice that your plant lacks moisture, simply begin watering it on a more regular basis. The issue of overwatering can be a much more dire situation, especially if you fail to notice it early. When your Blue toadflax is overwatered, it may contract diseases that lead to its decline and death. The best way to prevent this outcome is to choose a proper growing location, one that receives plenty of sunlight to help dry the soil and has good enough drainage to allow excess water to drain rather than pooling and causing waterlogged soils. If you overwater your Blue toadflax that lives in a pot, you may need to consider changing it to a new pot. Your previous container may not have contained soil with good drainage or may not have had sufficient drainage holes. As you repot your overwatered Blue toadflax, make sure to add loose soils and to use a pot that drains efficiently.
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How often should I water my Blue toadflax?
Blue toadflax needs water regularly throughout the growing season. Beginning in spring, you should plan to water this plant about once per week. As the season presses on and grows warmer, you may need to increase your watering rate to about two to three times per week. Exceeding at this rate can be detrimental to your Blue toadflax. With that said, you should also ensure that the soil in which your Blue toadflax grows remains relatively moist but not wet, regardless of how often you must water to make that the case. Watering Blue toadflax that lives in a pot is a bit different. Generally, you'll need to increase your watering frequency, as the soil in a pot can heat up and dry out a bit faster than ground soil. As such, you should plan to water a container-grown Blue toadflax a few times per week in most cases, versus just once per week for an in-ground plant.
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How much water does my Blue toadflax need?
There are a few different ways you can go about determining how much water to give to your Blue toadflax. Some gardeners choose to pick their water volume based on feeling the soil for moisture. That method suggests that you should water until you feel that the first six inches of soil have become moist. Alternatively, you can use a set measurement to determine how much to water your Blue toadflax. Typically, you should give your Blue toadflax about two gallons of water per week, depending on how hot it is and how quickly the soil becomes dry. However, following strict guidelines like that can lead to overwatering if your plant requires less than two gallons per week for whatever reason. When growing Blue toadflax in a container, you will need to use a different method to determine how much water to supply. Typically, you should give enough water to moisten all of the layers of soil that have become dry. To test if that is the case, you can simply stick your finger in the soil to feel for moisture. You can also water the soil until you notice a slight trickle of excess water exiting the drainage holes of your pot.
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How can I tell if i'm watering my Blue toadflax enough?
It can be somewhat difficult to avoid overwatering your Blue toadflax. On the one hand, these plants have relatively deep roots that require you to moisten the soil weekly. On the other hand, Blue toadflax are plants that are incredibly susceptible to root rot. Along with root rot, your Blue toadflax may also experience browning as a result of overwatering. Underwatering is far less likely for your Blue toadflax as these plants can survive for a while in the absence of supplemental watering. However, if you go too long without giving this plant water, it will likely begin to wilt. You may also notice dry leaves.
Read More more
How should I water my Blue toadflax through the seasons?
You can expect your Blue toadflax’s water needs to increase as the season moves on. During spring, you should water about once per week. Then, as the summer heat arrives, you will likely need to give a bit more water to your Blue toadflax, at times increasing to about three times per week. This is especially true of Blue toadflax that grow in containers, as the soil in a container is far more likely to dry out faster than ground soil when the weather is warm. In autumn, while your Blue toadflax is still in bloom, it may need a bit less water as the temperature has likely declined, and the sun is no longer as strong as it was in summer.
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How should I water my Blue toadflax at different growth stages?
Blue toadflax will move through several different growth stages throughout the year, some of which may require more water than others. For example, you will probably start your Blue toadflax as a seed. While the seed germinates, you should plant to give more water than your Blue toadflax will need later in life, watering often enough to maintain consistent soil moisture. After a few weeks, your Blue toadflax will grow above the soil and may need slightly less water than at the seedling phase. Then, once this plant is mature, you can begin to use the regular watering frequency of about once per week. As flower development takes place, you may need to give slightly more water to aid the process.
Read More more
What's the difference between watering Blue toadflax indoors and outdoors?
There are several reasons why most Blue toadflax grow outdoors rather than indoors. The first is that these plants typically grow to tall. The second reason is that Blue toadflax needs more daily sunlight than most indoor growing locations can provide. If you are able to provide a suitable indoor growing location, you may find that you need to give your Blue toadflax water a bit more often than you would in an outdoor growing location. Part of the reason for this is that indoor growing locations tend to be a lot drier than outdoor ones due to HVAC units. The other reason for this is that soil in containers can dry out relatively quickly as well compared to soil in the ground.
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Blue toadflax
Blue toadflax
Blue toadflax
Blue toadflax
Blue toadflax
Blue toadflax
Add to My Garden
Blue toadflax
Nuttallanthus canadensis
Also known as: Old-field toadflax
Blue toadflax grows to 25 to 80 cm tall. It features tall stems and purple to off-white flowers. The blue toadflax flowers from mid-spring to late summer in the Eastern part of North America.
Hardiness Zones
4a to 8a
Hardiness Zones
Weeds
plant_info

More Info

Flower Color
Flower Color
White
Pink
Purple
Blue
Bloom Time
Bloom Time
Spring, Summer, Fall
Leaf Color
Leaf Color
Green

Name story

Blue toadflax
Blue toadflax is sometimes still called Linaria canadensis although in 1988 it was reclassified as Nuttallanthus canadensis.
The new name honors Thomas Nuttall, a British naturalist and plant collector. Anthos is Greek for flower.

Symbolism

Protection, Hex breaking
icon
Find your perfect green friends.
Plan your green oasis based on your criteria: plant type, pet safety, skill level, sites, and more.
Download the App
weed

Weed Control

weed
Weeds
Blue toadflax is a weed that is native to eastern North America from Ontario to Nova Scotia, south to Texas and Florida, and west to Minnesota, Oregon, Texas, and California. It is commonly found growing along roadsides and in fields, where it becomes noticeably weedy. The only country of the world where blue toadflax is considered invasive is Brazil. Exercise caution as parts of this plant are poisonous if ingested. To control spread, the normal methods for removal would be pulling the weeds out by hand to include the roots system or use of an herbicide.
How to Control it
If unwanted, blue toadflax can be physically removed. Once it starts to flower it can be more difficult to remove, so it is best to deal with it early to prevent spreading. Start by pulling out the blue toadflax as much as possible. It should come out easily as it does not have very deep roots. Collect all parts of the plant and dispose of it appropriately. If the blue toadflax regrows by itself after a period of a few weeks, pull again and apply a chemical weed killer to the affected area, being careful not to spray other plants.
Show More more
icon
Do you have weeds in your garden?
Differentiate them from your plants by a picture, and learn how to control them.
Download the App
distribution

Distribution Map

Habitat

Bare areas and grassland

Map

distribution map
Native
Cultivated
Invasive
Potentially invasive
Exotic
No species reported
question

Questions About Blue toadflax

Watering Watering Watering
Sunlight Sunlight Sunlight
Temperature Temperature Temperature
What is the best way to water my Blue toadflax?
more
What should I do if I water my Blue toadflax too much or too little?
more
How often should I water my Blue toadflax?
more
How much water does my Blue toadflax need?
more
How can I tell if i'm watering my Blue toadflax enough?
more
Show More more
icon
Get tips and tricks for your plants.
Keep your plants happy and healthy with our guide to watering, lighting, feeding and more.
Download the App
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Your Ultimate Guide to Plants
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product icon
80+ scholars in botany and gardening
ad
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