Can I grow lettuce and tomatoes together in my Aerogarden? This and similar questions are asked in the groups every day. The answer is a definite, maybe.
Although there are rules that seem to make sense, gardeners violate them with impunity on a daily basis. The rules are great guidelines and will make for better crops and Aerogarden management. Fortunately, plants don’t know the rules, and just do what they need to in order to survive and thrive.
That being said, here are some considerations that may be helpful when choosing plants to grow together.
Germination Period
The first consideration is germination time. Once seeds germinate, the plants tend to shoot upwards and spread out. As the plants grow taller and wider, you will need to raise the lights. The plants that sprout later will be forced to do with weaker light and may be shaded by the older plants. Not an ideal growth plan. Not always fatal, but definitely a potential hindrance to maximum growth.
Plant Height
Similar to the first consideration, tall plants will force you to raise the lights. This will again force shorter plants to try to grow on less light. An example might be a two foot tomato plant and an eight inch lettuce plant. They are not compatible on so many levels.
Nutrient Concentration
This next consideration is frequently overlooked, and the quality of plants grown can suffer. Some plants require very little in the way of nutrients, while others require a massive concentration of them. Many types of lettuce can be grown successfully using just tap water. While flowering plants like tomatoes and peppers require very high concentrations of nutrients.
Although using a PPM meter is not really necessary, the numbers they provide will help illustrate my point. The ideal nutrient concentration for lettuce is about 500 – 800 ppm, while for tomatoes it’s between 1400 and 3500 ppm. As you can see, lettuce and tomatoes are not likely to grow well together. But it has been done!
Additional Nutrients
Another consideration is whether or not you want the plant to flower. Flowering plants need extra calcium and magnesium to set the fruit. On the other hand, the last thing you want herbs and lettuce to do is flower (bolt). Therefore, you may not want to mix the two types of plants.
Life Expectancy
You wouldn’t think that life expectancy would matter, but you would be wrong. It is not wise to grow a plant that runs its course in three or four months along with a plant the will keep giving for six months to a year or more.
Once a plant is finished, you want to remove it from your Aerogarden, and clean up the garden for replanting. However, if you have another plant in the same garden, and it is not finished, you may have a problem. Since the lights will be at a height to accommodate the remaining plant, a new plant will not get enough light to flourish. You could put another grown plant in the empty slot. Sadly, it is very difficult to get the roots into the slot without damaging them.
Conclusion
There are a number of considerations when planting your Aerogarden. Although each one ignored can create a problem for the gardener, many growers ignore one or more of these considerations and do fine.