Microgreens can be thought of as a newborn plant. Like human newborns, these baby seedlings require protection from harsh environmental conditions. For this reason, it is often easier to grow microgreens indoors as long as the plants are receiving enough light. However, microgreen growers, especially those who sell their harvest for profit, may want to start growing microgreens the outdoors in order to take advantage of some extra space. Although it can be more difficult to grow microgreens outdoors, it is possible.
Microgreens can be successfully grown outdoors in mild weather as long as the microgreens are grown in a pot or container. In addition, the microgreens should not be exposed to hot, direct sunlight. Finally, microgreens grown outdoors should also be protected from wind and pests.
The rest of this blog post will give you some tips for successfully growing microgreens outside.
Lighting Requirements For Microgreens
Microgreens will not do well in direct sunlight. It is best to put them in a location with partial shade. Planting on the north side of your home will work best. If you must grow your microgreens on a south-facing balcony or porch, provide some shade to guard your plants against direct sunlight.
It is particularly important to ensure that very young, delicate seedlings are not exposed to excessive sunlight. Seeds do not require any sunlight to germinate, and most types of microgreens have a blackout period. Therefore, it is nearly impossible to block out too much light during the first few days of the growing process.
Ideal Temperature Range And Humidity Levels For Microgreens
According to Alberta’s Ministry of Agriculture and Forestry, the optimum environment for microgreens varies by variety. In general, microgreens grow best in temperatures between 18°C and 24°C (64°F to 75°F) and relative humidities (RH) between 40 and 60 percent. Higher temperatures and levels of relative humidity promote disease and pest problems.
In many instances, the outdoor environment will not be ideal for growing microgreens. If you live in a location that is really hot and humid, you may want to consider purchasing an air condition unit and/or dehumidifier for your growing area.
Growing microgreens outdoors can also be tricky because the evapotranspiration (ET) rate, which is the rate at which the plant uses water, varies with temperature and humidity. Microgreens will use more water in hot, dry weather. This is because higher temperatures result in an increased vapor pressure deficit (VPD) which drives evapotranspiration. If you are growing microgreens hydroponically, it is very important to check their water levels frequently during hot weather. If the plants are dry for even a short time, they will die.
Conversely, microgreens will use less water in cooler temperatures. This can result in issues with damping off. If you are growing microgreens in cooler conditions, do not water as much or as frequently.
Pest Problems Encountered When Growing Microgreens
Unfortunately, you may have to deal with some pests such as caterpillars, bugs, worms, flies, or ants when growing your microgreens outdoors. The vast majority of microgreen growers avoid using pesticides, so this makes dealing with pests somewhat challenging. To avoid pest problems, you can use garden netting to keep potential pests from feeding on your microgreens.
If you do find that one of your growing trays or containers becomes infested with insects, isolate the tray from your other microgreen containers. This will minimize the chance of the problem spreading.
Apparently, the Australian Brush Turkey enjoys munching on microgreens. If you live in an area with these animals, check out the following video on how to handle these pests.
Growing Microgreens In Outdoor Containers
Planting microgreens in containers is the most convenient way to grow microgreens outdoors. You can move the containers indoors if necessary and it is easier to put your containers in the best location in your garden.
The process of growing microgreens outdoors is similar to growing microgreens indoor. However, outdoor growing tends to be more challenging because you cannot control the growing conditions. Here are some tips for growing microgreens in containers outdoors:
- When growing microgreens in containers, it is best to use potting soil rather than soil from your garden. Potting soil will have better drainage than soils that contain a lot of clay.
- Plant microgreen varieties that grow from big seeds such as sunflower or peas. These types of microgreens seem to do better outdoors than microgreen varieties with smaller, more delicate seeds.
- Plant your microgreens in a growing tray or a container with drainage holes.
- Check the soil moisture/water levels frequently. The plants will use water more or less depending on the temperature. Water your microgreens at least once a day – more if the soil surface gets dry.
- Water your microgreens with a gentle hose setting – strong water pressure could damage the delicate seedlings.
- Protect your microgreens from rainfall. The impact of raindrops can adversely affect the microgreens’ growth. You can protect your microgreens from rainfall by moving your growing trays/containers indoors during the rainfall event or by moving your growing trays/containers indoors or by covering the seedlings.
- Do not expose your microgreens to light too soon. A blackout period is an important step to growing microgreens with long, crunch stems. Neglecting the blackout period can result in shorter microgreens with a thicker and more fibrous texture.
Growing Microgreens In Outdoor Greenhouses
Growing your microgreens in an outdoor greenhouse can be a great way to combine some of the benefits growing indoors and outdoors. However, greenhouses have a tendency to get too hot and humid which can result in mold problems.
If you are going to set up a greenhouse, make sure your setup provides plenty of airflow. One way to do this is to add vents and fans to your greenhouse.
Growing Microgreens In The Ground
Microgreens can be grown in a typical garden bed, but it is generally not recommended. This is because it takes longer than growing microgreens in a container, and it is difficult to produce microgreens that are as tender as indoor microgreens. This partly due to the fact that it is more difficult to create a true blackout environment in a garden bed.
Soil Texture
Before planting your microgreens in the ground, you should also consider your garden’s soil texture. Your microgreens (like many other plants) will not grow very well in hard clay or soil that does not drain well.
You can perform the “squeeze” test to more fully understand your garden’s soil texture. Simply take a clump of moist soil in your hand and firmly squeeze it. If the soil is coarse and breaks apart easily, you have sandy soil. If the soil maintains its shape and does not crumble in your hand, you are probably dealing with clay soil. Finally, if the soil maintains its shape and crumbles when poked, you are one of the lucky gardeners who have loamy soil. In general, plants grow best in loamy soil. This is because loamy soil tends to drain well and provide nutrients to plants.
It is extremely difficult to change soil texture. However, if your garden bed is comprised of clay soil, there are a few things you can do to amend the soil. The best way to amend soil is to add organic matter as it makes the soil more porous and provides plant nutrients. Unfortunately, soil amendments may be more costly than it’s worth. If you have clay soil, I would highly recommend just planting your microgreens in containers.
Garden Pests
In addition to the pests mentioned in the previous section, growing microgreens in the ground exposes them to additional pests including rabbits and squirrels.
