Space isn’t everything when it comes to growing a vibrant, healthy variety of romaine lettuce. Therefore, if you’re looking for the best way to cultivate your own using just pots or other similarly-sized containers, this guide is for you. Luckily, growing this nutritious leafy vegetable within a confined space doesn’t have to be complex or time-consuming.
Here’s how you can grow romaine lettuce in pots:
- Choose the right timing.
- Choose the right types of pots.
- Prepare the pots.
- Choose the right soil.
- Plan the pot’s placement.
- Plant the seeds.
- Use fertilizer.
- Water the soil as needed.
- Watch out for pests and diseases.
- Harvest the lettuce.
These steps might seem a bit extensive at first, but I assure you that after reading through the following sections, growing romaine lettuce in a pot will feel easier than ever. Therefore, keep reading to find out more about the best way to get the healthiest, brightest-looking crop possible.
1. Choose the Right Timing
The most important factor to consider when growing romaine lettuce in a pot is timing. Finding the right season and month to plant the seeds can often make or break your end result. Therefore, you’ll want to keep in mind that romaine is usually a cool climate variety, which means that it thrives during colder, humid months.
The ideal temperature for growing romaine lettuce is above 50 °F (10 °C), therefore keep that in mind if you live in an exceptionally cold area. For this reason, the transitional period between late winter and early spring is usually the perfect time to plant your seeds if you want to give them the best chance of survival.
Although the best temperature to grow romaine lettuce in hovers around 60 °F (15.6 °C), and can even go as high as 75 °F (23.9 °C), when the climate gets much hotter than that, the plant is unlikely to grow, or at least not to its full potential.
This doesn’t mean that there’s absolutely no leeway when it comes to finding the right temperature, as the plant can withstand being left in an environment that falls a bit below or above the recommended level. However, generally speaking, this is the range you’ll want to aim for.
In simpler terms, you usually want to plant your romaine at least two weeks (but you can go up to two months) before the last frost date. If you’re unsure when this period falls on your location, check out this handy guide.
2. Choose the Right Types of Pots
Now that you’ve figured out the timing, it’s time to choose the right type of container that will help your seeds grow as much and as healthy as possible. Now, although planting romaine lettuce in pots is always doable, this doesn’t mean that any type of pot will do.
First of all, pot size matters, even though it’s not the most important factor you’ll have to consider. You’ll want to look for an option that’s at least 5 inches (12.7 cm) deep to give your plant’s roots enough space to grow. However, you’ll rarely need to find a container deeper than 12 inches (30.5 cm) as romaine typically has relatively shallow roots.
Moreover, you’ll want to opt for a pot that has a diameter of at least 14 inches (36 cm). Although the roots and the plant itself don’t grow very tall, it can gain a lot of volume throughout its lifetime, which is why you’ll want to account for any possible spacing issues beforehand.
Finding the right-sized container is also important because, in a smaller container, the soil tends to dry out much quicker, depriving the roots of the much-needed water (I’ve already mentioned the variety’s need for a humid environment).
Additionally, you’ll want to make sure that your chosen pot is equipped with several drainage holes. These are essential, and their importance can’t be overestimated. They allow the water to get out of the pot without spoiling or weighing down the soil. However, if you’ve found the perfect container but it lacks drainage holes, you can still use it as long as you drill some yourself.
While on this topic, always make sure to put a water collecting dish underneath your pot, as those drainage holes release much more excess water than you’d think.
The material of the container doesn’t really matter as long as it’s able to retain humidity without making the soil soggy. Traditional terracotta pots are an excellent choice for this purpose, as their density and texture allow for very well-balanced moisture levels.
Although in the ideal environment, the pot’s material doesn’t hold much impact, those growing their plants in less than ideal temperatures might want to be more careful when making this same choice. As a rule of thumb, though, you can’t go wrong with clay. The material is much more forgiving when it comes to temperature variations, and its porous quality allows the soil to always maintain the right humidity level.
Another factor you’ll want to consider if you’re living in a particularly hot or cold environment is pot color. This may seem intuitive, but I still want to reiterate the importance of choosing dark-colored options for colder conditions and light-colored alternatives for warmer ones. By doing so, you’ll be optimizing the temperature within your container regardless of the climate.
Furthermore, you’ll want to make sure that your pots are thoroughly clean and free from any impurities or debris if you want your seeds to have the best chance of survival. For this reason, it’s crucial to ensure that you carefully clean and dry your containers before use.
To do so, ideally, you’d want to use hot water combined with a bit of bleach at a ratio of 10:1. However, maintenance requirements can vary a lot depending on the material and size of your pot, which is why as long as it’s dirt and debris-free, you won’t need to worry much about the cleaning process.
3. Prepare Your Pots
After choosing the right type of pots, it’s time to prepare them for planting. As I previously mentioned, it’s essential to clean and dust your containers beforehand. Ideally, you’d want to soak them in your water-bleach solution for at least an hour to sanitize them properly.
This won’t only eliminate any residue or debris, but it will also ensure that there are no harmful microorganisms that could potentially harm your romaine lettuce later on. It’s hard enough to deal with pests and diseases that appear later in the growth cycle; at least prevent the ones you’re able to.
After the pot is clean and equipped with its drainage holes, it’s time to fill it up with soil. I’ll cover how to find the right type of soil to use in the following section. However, remember that before adding it in, you’ll want to cover the bottom of your pot with a piece of paper, a cloth, or a newspaper.
The reason why you need to do this is that the drainage holes are big enough to fit chunks of soil through them. Therefore, without a barrier, soil can start coming out of the pot along with the water, leading to a plethora of possible problems.
Additionally, when filling the pot with soil, remember that you’ll want to leave at least 2 inches (5 cm) of space at the top so that the matter doesn’t overflow once watered.
4. Choose the Right Soil
The pot is prepared, and you know everything you should about how to properly fill it with soil. The next thing you’ll want to figure out is what type of soil suits your conditions and lettuce variety best. With so many choices oversaturating the market, trying to find the right alternative for you can often feel overwhelming.
First of all, the soil you’ll want to go for should be rich in minerals and moist enough by itself to cater to the variety’s high water requirement. Potting soils are usually the way to go, as garden soils can be too rough due to their high sand or clay content.
Additionally, the potting soils tend to be looser than garden soils, which means that the roots will have more space to breathe and retain the necessary amount of water.
However, if you’re still not sure about which brand to invest in, you can always make your own variety at home. All you need to do is mix compost, perlite, and vermiculite in equal parts, and you’ll have the richest, most ideal base for your romaine lettuce seeds to grow in.
Additionally, you’ll want to add some organic matter to the mix to increase the necessary nitrogen levels. The right amount of organic matter for your blend can vary, but usually, you’ll want to go for a 1:5 ratio.
Through this mix, you’ll be able to provide your plant with all the required nutrients and water content while giving it space to breathe and grow. If the substance doesn’t seem moist enough, you can always add humidity by pre-watering it before planting the seeds.
5. Plan the Pot’s Placement
If you want to give your lettuce the best chances of survival, you’ll have to find the ideal place for it on your property. Generally speaking, the plant thrives under the sun; however, the ideal sun exposure may vary depending on the climate they’re growing in.
For example, if the temperatures are exceptionally high, you’ll need to put your pots in partial shade, as otherwise, the crops will suffer. Additionally, excessive sun exposure can dry out the soil relatively quickly, which, as I’ve already covered, can be problematic.
Therefore, as a general rule of thumb, try leaving your plant in a sunny area during the day and keep it shady in the afternoon. I assure you you won’t be disappointed with the results.
6. Plant the Seeds
Now that you’re fully prepared, it’s time to actually plant the romaine seeds. You can get your hands on some high-quality varieties at any local garden supplies store. Remember that investing a bit extra at this point can really pay off in the long run.
Choosing between seeds or seedlings is a matter of preference. If you’ve got enough time and patience, I suggest going with seeds as they tend to generally be more affordable.
Additionally, it’s important to wait for the temperatures to drop a bit before starting the planting process. Although you can’t control the weather throughout the whole growth cycle, at least make sure to give the seeds a head start by planting them at an ideal temperature.
If this doesn’t seem feasible, you can always soak them in cold water for a few hours before burying them, which will put them at a better odds to thrive during hot summer months.
You can sow your seeds directly into the chosen pot by poking small holes around ½ inch (1.27 cm) deep. You’ll want to place three seeds inside each hole and cover them with another layer of soil. This is necessary because not all of them will be able to sprout.
Remember to leave at least 4 inches (10 cm) of space between each hole to give the plant space to breathe and grow.
If you’ve opted for seedlings, it might be necessary to gently pull their roots first before placing them inside the soil. As I’ve mentioned, a cold water bath beforehand could do wonders for their health and longevity.
Lastly, you’ll want to keep the pots indoors for the first few days to better protect the seeds and give them a better chance of survival. You can then slowly start to take them outside for a few hours each day (assuming the conditions are adequate) until they’ve begun to sprout and are ready to be left outside for a full 24 hours.
7. Use a Fertilizer
Once the seeds have sprouted, it’s time to think about fertilizers. Although it’s not an absolutely necessary step, it can significantly help your crop’s quality and growth rate. The ideal time to start this process is once your plant has reached the 8-week old mark.
From that point on, you’ll want to fertilize your plant at least once every two weeks. Luckily, the process itself is neither difficult nor time-consuming, and there’s no shortage of high-quality fertilizers on the market.
You can use any high-quality organic fertilizer by mixing it with water first (using the ratio recommended by the manufacturer) and then adding it to the soil at the rate I mentioned in the previous paragraph.
Generally speaking, no matter the fertilizer brand you choose, always try to look for an option that provides equal parts potassium, nitrogen, and phosphates like a 4-4-4 or 10-10-10 fertilizer.
8. Water the Soil As Needed
Your seeds/seedlings are now growing faster and healthier than ever; however, no amount of fertilizer you use can make up for a bad watering schedule. For this reason, it’s important that when it comes to romaine lettuce, watering should be your number one priority.
Romaine lettuce is mostly water, which explains its extensive need for moisture. Moisture levels can affect the taste of your lettuce, as inadequate hydration could lead to a bitter, unpleasant end result instead of the sweet and fresh taste you were looking for.
However, more isn’t always better, as overwatering could potentially lead to rot and fungal growths that could kill your plant altogether. For this reason, it’s crucial to maintain a regular once-every-other-day watering schedule. This will allow you to provide the lettuce with the level of hydration it needs without overdoing it.
Remember that the best time to water your romaine lettuce is bright and early in the morning. By doing so, you’ll allow the plant enough time to absorb the necessary minerals and nutrients without the sun and heat drying out the soil too much.
9. Watch Out for Pests and Diseases
This is probably the least pleasant step of the whole process, but unfortunately, it’s crucial in ensuring your plant’s health and longevity. As you may know, there’s no shortage of pests and diseases that can cause serious harm to a plant as delicate as romaine lettuce.
However, as long as you catch the potential harm in time, chances are you’ll be able to salvage your crops.
When using pots as a vessel to grow your plants, it might be a bit easier to notice any unusual changes that might become a cause for concern. For this reason, when doing your daily checks or frequent waterings, it might be a good idea to take the time to inspect the plant for any unexpected visual or textural changes.
Before diving into the most common pests and diseases that you should look out for when growing romaine lettuce, I want to expand a bit on a phenomenon that’s just as dangerous but even more widespread: bolting.
Bolting
Bolting is one of the main conditions that can render a lettuce crop inedible. The term stands for the process that shifts leafy growth into flower production. As you can imagine, this can significantly affect the taste and texture of your crop to the point that it’s not enjoyable or safe to eat.
This phenomenon can be caused by a number of factors you’ll want to look out for. From high temperatures to inadequate moisture levels, there are a lot of variables that could cause your plant to bolt.
Luckily, as long as you’re aware of the concept, you can take some measures to prevent it before it even happens. For example, by choosing the planting schedule I previously suggested in the “Plant the Seeds” section, you’ll be able to significantly decrease the possibility of this phenomenon.
Additionally, maintaining a cool and humid environment at all times around the pots could also increase the chances of a successful crop.
Pests
Some of the most common pests that attack romaine lettuce include aphids and slugs. Both can damage the plant in different but equally destructive ways.
For example, aphids are hard to detect but easy to get rid of through the use of any insecticidal solution. All you have to do is spray it thoroughly throughout the leaves and soil. On the other hand, slugs or snails leave bigger bite marks throughout the lettuce leaf, making them easier to detect. However, getting rid of them will often require a bit of creative thinking.
Diseases
The most common diseases in romaine lettuce are fungal in nature. Unwanted growths such as mildew and leaf spots are often a source of worry for many lettuce growers. They often cause the leaves to (either partially or fully) turn yellow and brown, and if left untreated, they could cause the plant to die.
While mildew could potentially be treated with sulfur, if your plants suffer from leaf spots, I’m afraid there’s nothing you can do to prevent them from dying out.
Additionally, don’t forget to attend to the soil as often as possible to keep it free from any weeds or other unwanted growths that could smother your plant if left unattended.
10. Harvest the Lettuce
Although not difficult, growing romaine lettuce is a process that requires a bit of patience, as it can require up to two months to fully develop. However, after weeks of maintenance, fertilization, and watering, you’ll finally be able to enjoy the sweet, crispy, bright flavor that only homegrown romaine lettuce can offer.
It’s normal for your seeds to grow and mature at different rates, which is why their harvest is more of a process than a one-time activity. You can always pick out the outer, more grown layers while waiting for the inner ones to reach the mature stage as well. You’ll be able to tell when this happens as, by this time, the leaves should have reached a height of at least 6 inches (15.24 cm).
Be careful to keep a close eye on your plant as the harvesting day approaches because their taste and texture will suffer if left too long. Additionally, you’ll want to harvest the lettuce as early in the morning as possible, as the additional sun exposure could wilt the leaves (remember that by this point, the temperatures will have significantly increased).
After harvesting the plant, you’ll be able to store it in the fridge for up to ten days. To retain optimal freshness throughout the storing process, you’ll want to first give your lettuce an ice bath. Afterward, keep it wrapped in a ziplock bag to optimize its taste, texture, and longevity.
Conclusion
Growing romaine lettuce in pots is a process that requires a bit of time, patience, and care. However, by following the right steps, you’ll be able to harvest a bright, sweet, and crispy end result that doesn’t even compare with what you can buy at your local stores.
Therefore, give this guide a try and use those empty pots to grow your own romaine lettuce; I promise it will be worth it.
