Due to the fact that the raised beds are “soil free”(everything in the bedding mix is mostly inert: peat moss, perlite, coco coir, mulch, and hydro-ton), we have to keep a close eye on the plants to make sure they are getting enough nutrients.
Here are some issues we are noticing:
Yellowing on the lower leaves usually signifies phosphorus or sometimes nitrogen deficiency. The fact that both the tomatoes and watermelon are heavy feeders, and have both been bearing a lot of fruit, we felt it would be best to feed some additional potassium to make sure stems and other structures were well fed.
As a result of these symptoms the following fertilizers were used:
1. Steamed Bone Meal
High in Phosphorus and Calcium, helps bring fast responding phosphorus into the medium, along with calcium also needed to combat blossom end rot that we were getting in some cases.
2. Worm Castings
High in available Nitrogen to help development of chlorophyll and leaves without burning the plant. Castings are high in humic acids that help the plant survive stress and provide various micro-nutrients for development.
3. Sifted BBQ/Smoker ashes
Potash as it can be known, is high in potassium from the burning of plant matter to its ashes. These ashes can be readily used as water soluble material to provide potash (Potassium) to other plants.
A few piles of N, P, and K (Worm castings (Dark Brown), Steamed Bone Meal (Light Brown), Potash (Whitish Grey). And yes, cats may be attracted to the Bone Meal, so it is a good idea to keep them away and water the topdressing in.