Growing Lettuce in GrowBoxes

Growing Lettuce in GrowBoxes

Growing Lettuce in GrowBoxes

GrowUrban's self watering GrowBoxes provide an easy way to grow fresh healthy salad.  The perfect conditions in a self watering GrowBox help lettuce grow faster and remain sweet and non-bitter. Below are a few simple tips to help you grow even better salad.

All lettuce varieties will grow well in a self-watering GrowBox, but some do not make effective use of the space. For this reason we tend to grow upright loosehead lettuces such as cos, with a few frilly lettuces to add some "body" to the salad, rather than crisphead/iceberg lettuces. Our favourite combination at the moment is one six-cell punnet of Zealandia Cos and one punnet of Zealandia Gourmet Mix. We also occasionally grow Buttercrunch, but because of it's larger size you can only fit 6 in a GrowBox.

Choosing Plants

Starting with healthy seedlings is very important. Things to look for when choosing plants include:

  1. Darker coloured leaves. While some varieties are naturally lighter, darker leaves mean that the plants have been receiving enough light.
  2. Not "leggy". Leggy or elongated stems are a sign that the plant has not had enough light.
  3. Not too large. In our experience larger plants do not transplant well. Plants between 3 and 6 cm tall seem to work best.
  4. No aphids. Check both under the leaves and in the center of the plants.
  5. Healthy looking. No bruising, dead or dying leaves, diseases, etc.


plant in three rows of four plants (Cos/Gourmet Mix combo) or two rows of three plants (Buttercrunch) by popping the plant out of the punnet, making a hole in the potting mix with your fingers, dropping the plant in the hole and firming the potting mix around it. When everything is planted water in gently from the top (you can add liquid seaweed to this to help reduce transplant shock, but most of the time we don't bother) before filling the reservoir with water.


Pick leaf by leaf, lower leaves first, using a sharp knife. Pick regularly to avoid the GrowBox becoming overgrown, which can lead to disease issues.

Pest Control

Occasionally you may have issues with pests. Below are some of the more effective and natural controls available.

  • Caterpillars: The most common cause of holes in lettuce leaves is the looper caterpillar (caterpillar of the brown moth). You can remove the caterpillars by hand, which is time-consuming and tedious, or use something like Kiwicare Organic Caterpillar Biocontrol, which is the option we usually choose. Moving the GrowBox away from areas where moths live can also help.

  • Slugs and Snails: Some of our SlugStoppa tape around the GrowBox will stop slugs and snails getting into your GrowBox and eating your plants.  It is also chemical free and pet safe.

  • Aphids: We have had very good success using the parasitic Aphidius colemani, available from Bioforce. They are somewhat expensive as Bioforce does not offer them in quantities less than 100 Aphidus, which is enough for a large area, but they keep the aphid numbers low for several months at least. They also leave no chemical residue on your food.

In Conclusion.....

Self watering planter boxes are great for growing lettuce in, with the fast growth and perfect amount of water combining to keep your lettuce sweet and non-bitter.  If you have any questions please contact us, we are happy to help.

Posted: Friday 6 January 2017