Not only does the Gai Lan have certain preferences regarding how much water it receives, but it also cares deeply about how you provide that water. In fact, if you don't use the proper watering technique, you risk harming your tomatoes. The best way to water Gai Lan is to apply the water directly to the soil in a slow and gentle manner. You should not pour all of the water into the soil at once, and you should not do overhead watering for your Gai Lan. Although you should water slowly, you should also water deeply to ensure that all of the soil in which your Gai Lan grows is sufficiently moist.

If you find that you have overwatered your Gai Lan and you are concerned about the associated risk of disease, you should intervene immediately. Often the best approach for an overwatered Gai Lan is to uproot it from its current growing location. Once the plant is out of the ground, you can allow its roots to dry a bit before planting it in a new growing location. Ensure that the new growing location has soil with good drainage. If you grow in pots, you may also want to move your plant to a pot with more or larger drainage holes. In the case of underwatering, all you will need to do is increase the frequency with which you supply water to your plant.

Overall, Gai Lan requires a significant amount of water throughout the growing season. To meet that high water need, you'll need to water early and often throughout the spring and summer. During the earlier parts of the growing season, you should water your Gai Lan about once or twice per week. As the season progresses, you should increase your watering frequency. You may need to water it twice per day or more during summer, depending on the weather. After your Gai Lan have gone through their major seasonal growth phases, you can reduce the frequency of your watering to about once per week until the end of the growing season.

Since Gai Lan are incredibly popular, with many professional and amateur gardeners growing them successfully, we have a pretty clear idea of how to care for these plants. That understanding includes specific knowledge about the precise volume of water an average Gai Lan should receive. Generally, Gai Lan will require about 1 - 1.5 inches of water per week. That volume should be dispersed evenly through your weekly watering. As the weather gets warmer, you may need to supply more water, but in most cases, two inches per week is a good baseline amount.

Underwatering and overwatering can both occur as problems for your Gai Lan, and both these problems can manifest with similar symptoms. For example, foliage discoloration and wilting can both result from either overwatering or underwatering. When your Gai Lan is underwatered, its leaves will be curling and drooping at the beginning. You will see a bunch of leaves turn less vigorous. Underwatering is also likely to cause stunted growth and poor overall development as both the flowers and this plant require a high amount of water. Overwatering is more likely to lead to disease, including rot. Overwatering may also lead to unpleasant smells rising from your plant's soil. The symptoms of underwatering will show up quicker than overwatering. Overwatering can also be evident in soil conditions. Mainly, if you notice a lot of standing water or waterlogged soils, overwatering is likely to occur.

As alluded to above, your Gai Lan's water needs will repeatedly change throughout the seasons. During most of spring and summer, you should water your Gai Lan about once every week. As the heat of summer arrives, you should plan to increase your watering frequency to once or twice per day. In the late summer and fall, towards the end of the harvest period, you can reduce your watering frequency to about once per week. After harvest has ended, you can cease watering as your Gai Lan has reached the end of its life cycle and will require no further soil moisture. The maintenance schedule of Gai Lan will require you to alter the amount of water you provide depending on the plant's current growth stage. Early on, especially if you grow your Gai Lan from seeds, you'll need to provide water often enough to maintain consistent soil moisture, which encourages root development. When the plant becomes old enough to produce flowers, it will likely need even more water. During the fruit development growth stage, your Gai Lan will likely need the most water out of any growth period, at times requiring water more than twice per day. Following that phase, the water needs of Gai Lan will decline significantly.

Whether you grow Gai Lan indoors or outdoors can also play a role in how you water them. Gai Lan that grows outdoors may receive water from natural rainfall, which will reduce the amount of supplemental water you should supply. However, it is incredibly rare for rainfall to adequately replace your watering entirely. Plants that grow indoors, along with any Gai Lan that grows in a container, will need to be watered more frequently than those that grow in the ground outdoors. If you choose this route, please make sure that the plant gets enough water by checking the soil moisture within your pot often to keep your Gai Lan healthy.

Exact needs vary, but a minimum of 6 to 8 hours per day is a good rule of thumb for Gai Lan to grow and produce fruit.

Gai Lan requires full sun, meaning that it should be grown in a location that gets direct sunlight that isn’t blocked by obstacles such as trees, fences, or buildings. In general, the faster the plant grows, the more hours of sunlight it will need. Morning sun is best for photosynthesis.

Gai Lan should not need to be protected from the sun in most climates. Those who live in a desert or near the equator may find that the sun is too harsh for the types of plants they want to grow, but this is the exception.

All plants need sunlight to convert into energy. Plants that have a short growing season need even more light and energy than those that grow slowly, as they need to complete all their processes to grow and produce fruit within just a few months. The first symptoms of insufficient sunlight in Gai Lan are pale and yellow leaves that are not able to generate enough chlorophyll to keep their healthy green color. The leaves may eventually fall off, and new growth is small and weak. The plant may become leggy and sparse as it stretches toward the available light. Finally, without enough light the plant will not be able to produce large, high-quality edible leaves or fruit. Gai Lan needs to devote a lot of energy into growing leaves and fruits, so if there isn’t enough light available for it to convert, the harvest will suffer.

Gai Lan can get sunburned from intense sunlight, especially when coupled with high temperatures and not having enough water. Afternoon sun tends to be most likely to burn plants. Scalded leaves develop faded patches of light brown to white on the areas at the top of the plant that are exposed to the most sun. They are especially vulnerable to this right after being transplanted from a shadier location to being in full sun. Transitioning plants gradually or providing them with a barrier while they are adjusting can help prevent sunscald in young plants. In many cases, Gai Lan develops leaves that are large enough to protect fruits from the strongest rays of the sun. However, if intense sunlight is in contact with fruits, they can also be damaged. Avoid over-pruning those protective leaves so that the fruits don’t get burned.

Gai Lan may become unbalanced if it gets significantly more light on one side than the other. Ideally, you can plant your Gai Lan in a location away from obstacles that might block light, and where the distribution of sunlight is even on all sides. Be careful about planting tall species next to those that grow closer to the ground. It may not be obvious when the crops are first planted, but over time the taller plants may begin to block the amount of sunlight that can reach the shorter plants. Morning sun helps to dry dew and precipitation, which helps prevent infection from diseases that can develop when water sits on the plant. If you are watering or irrigating your Gai Lan, this should be done in the morning.

There is an ideal temperature range that makes Gai Lan feel at home. Under these temperature conditions, it's unlikely that you’ll have any issues with cold or hot damage to the foliage, but changing leaf colors can absolutely be a sign that Gai Lan isn’t happy. Try to keep your Gai Lan well within its preferred range of 70-85℉(21-30℃), but don’t panic if the temperature creeps up past 85℉(30℃) during the day or down to 70℉(21℃) at night.

If your Gai Lan happens to be planted outside, then there’s not much you can do to try to move it indoors. However, you can certainly provide cover in ways that will help it survive any extreme temperatures that may arise unexpectedly. For instance, you can always use a few stakes and some cloth to put together a shade tent that will block out much of the sun’s intense heat from direct sunlight exposure. Similarly, Gai Lan can be protected from the extreme cold and especially chilly winds by building a small greenhouse around the plant, which will create a greenhouse effect and warm the plant up. This can be done using garden stakes and any sort of clear or translucent plastic you may have around; if you have greenhouse plastic such as polycarbonate laying around, this works perfectly. Remove the greenhouse once temperatures warm up to 40℉(10℃) at night.

Generally speaking, Gai Lan needs to stay within its preferred temperature range all year long. However, that doesn’t mean that care should stay the same all year long. During the warmest months of the year, Gai Lan will need a little extra shade and a bit more of a breeze to help it cope with the hottest days. On the other hand, it may need to be moved away from chilly windows and doors during the cooler months in climates where temperatures drop below 40℉(10℃) at any point in the year.

Keeping your Gai Lan at the right temperature can be fairly simple. Depending on where you grow it, Gai Lan can be fairly easy to accommodate. For indoor growing, you can easily move the plant to different locations within your indoor space that best meet its temperature requirements. Avoid placing it near air conditioning vents, heaters, doors that open frequently, or drafty windows. It is a little more difficult to control the temperature around your Gai Lan if it’s grown outside. Of course, if it’s planted in a pot, you can simply bring it indoors when the temperatures outside get too hot or too cold for Gai Lan, but otherwise, you may need to take different measures to protect it from extreme heat or cold that may damage it irreversibly. Try placing Gai Lan under cover to protect from both the harsh sun that can overheat it and any cold wind that could be potentially deadly for your plant.