Although winter hasn’t left us, we can see that spring is coming! The days are getting longer and when the sun is out, it is stronger than it was in December.
My houseplants have noticed! They are once again actively growing. After giving them a period of winter rest, it’s time to resume regular fertilizing to support new growth.
I’ve talked about the major nutrients in fertilizer before, but here is a little refreshed course:
N-P-K. All fertilizer packages have three numbers listed on the label. The most common type used for houseplants that aren’t flowering varieties have all number equal. 20-20-20 is the one I use at home.
N is the short form for nitrogen. This element encourages the growth of healthy foliage. P represents the nutrient phosphorus which benefits flower, fruit and root production. Finally, K is for potassium. It helps with the overall health of the plant.
In the all-purpose fertilizer I use, each scoop of water-soluble powder has 20% of each of those three major nutrients. The actual numbers aren’t that important for all purpose fertilizer, just that fact that it feeds all parts of the plant equally. You may see a brand that has 10-10-10 or 1-1-1 on the label. There is either 10% or 1% of the nutrient available for the plants to use.
Always be sure to read the package directs for correct mixing rates. Fertilizer must be dissolved in water for the roots to be able to absorb food from the soil. You may have a water-soluble powder, a concentrated liquid, or slow release pellets in the package you buy.
The powder or liquid concentrate needs to be added to water at the rate recommended by the manufacturer. My package states to mix 5 ml (or 1 teaspoon) of power in each liter of water and to apply the solution once per month. There is a two-sided scoop right in my container that has one end measuring 5 ml and the other 15 ml. This makes the task very easy.
If you think twice as much is twice is good, you are wrong! A solution that is too strong has the potential for burning plant roots. You can choose to mix the fertilizer 1/2 strength and us it every two weeks or 1/4 strength and apply it weekly. That’s perfectly fine for your plants too.
Slow release fertilizer pellets are meant to be applied directly to the soil at a rate determined by the pot size. Each time you water your plant, a bit of fertilizer dissolves, providing a slow constant feed. Just be sure that you don’t put the pellets up against stems or on low-lying leaves. That may cause burn to the tissue.
If you have flowering houseplants, choose a fertilizer formula recommend for those plants. The nutrient ratios will encourage healthy flower production.
Other than resuming fertilization, this is the perfect time to repot your plants if they have outgrown their container. Be sure to choose a container the next size up: if you have an ivy in a 6” pot that is hard to keep watered and has the soil entirely full of roots, choose an 8” pot as its next home.
If you used a 12” pot, the plant wouldn’t grow any new leaves until roots grew out to the side of the pot. That may take quite awhile!
Use a good quality all purpose indoor potting soil for houseplants. There are specialty mixes available for specific plants too. African Violet mix, cactus soil and orchid bark are a few to choose from.
This is also the time of year I will take my plants into the tub and give them a tepid shower. This washes winter dust off the leaves. The constant flush of water through the soil will also leach away any excess fertilizer salts. They are a crusty whitish layer that can accumulate on the soil surface or on the pot itself.