March's new growth begs water, fertilizer

Most houseplants resume growth in March. Some broke their torpor in late February. Water them to support the change, and fertilize.

Water

Since a plant uses water based on how many leaves it has and how much light there is to break water into its basic elements, a pot that didn't dry down for 3 to 4 weeks in the dead of winter may once again need water weekly as spring begins. Check for water needed by pot weight or the limpness or firmness of the plant's new growth.

We water the jade at right and most other houseplants according to the plant's water use, not a calendar count. The more hours of light there are each day and the more leaves it has, the more quickly it uses up the water its pot can hold. So we water when the pot begins to lighten and the jade leaves change from plump to thin. That's every month or so in winter but more often beginning in March. (The history of this jade's cut-back...

The jade we left too long in late fall cold budded out a few weeks after cutback but those new shoots pretty much sat still all winter. Now they're elongating and adding more leaves.

The jade we left too long in late fall cold budded out a few weeks after cutback but those new shoots pretty much sat still all winter. Now they're elongating and adding more leaves.

... and the whole story in short: Cold killed its top one fall, so we cut it back, and it grew back. Three years later, cold killed it back again, more extensively. Then, we decided to divide it as well as cut it back hard. 

Photos are left to right: From the beginning of the story, after the first cold caused us to cut, after the second cold and division and cut, and finally one of the sections one year later.

Photos are left to right: From the beginning of the story, after the first cold caused us to cut, after the second cold and division and cut, and finally one of the sections one year later.

Water thoroughly every time a plant needs water.
A pot filled with roots and loose potting soil can hold about 1/3 its own volume of water. For this jade's pot that's about as much water as is in the bottle next to it in these pictures. Once it has been given that much water it can hold no more and the excess begins to seep out the drain hole.

Gradually dropping oldest leaves: A cry for fertilizer

When we see the older leaves of a plant turning pale and withering away even though they're in good light we know the plant is cannibalizing its own older tissues to build new. Time to fertilize.

This Kalanchoe 'Chocolate Soldiers' hasn't had any fertilizer in the year it's been growing on from a cutting. Only now has it begun to steal from its lowest leaves to create new. Time for fertilizer. Note: The photo's not fuzzy! The plant's covered with fine hairs, a defense against hot dry seasons in the species' homeland. Read the fuzz on a plant as a cue: like succulents, they need to dry down a bit between waterings.

This Kalanchoe 'Chocolate Soldiers' hasn't had any fertilizer in the year it's been growing on from a cutting. Only now has it begun to steal from its lowest leaves to create new. Time for fertilizer. Note: The photo's not fuzzy! The plant's covered with fine hairs, a defense against hot dry seasons in the species' homeland. Read the fuzz on a plant as a cue: like succulents, they need to dry down a bit between waterings.

The sugar (carbohydrate) a plant
  makes from carbon in the air and
  hydrogen in water turns into
  cellulose that builds new cell
  walls.

  Other essential building blocks
  including as nitrogen, phosphorus,
  potassium and "micronutrients"
  (iron and others) come from
  what's already in the plant or from
  soil minerals or from fertilizer.

  Since the potting mixes we use
  to provide good drainage do not
  contain mineral soil but bark and
  peat, fertilizer's important to
  support new growth.

Which fertilizer? Balanced formula with micronutrients

For potted plants we use fertilizer that contains micronutrients as well as the big three elements -- "trace" elements such as iron and copper as well as nitrogen, phosphorus and potassium. Read the fertilizer label to learn if it contains not only the big three but the others, too. Some organic fish- or seaweed products are good. 7-7-7 African Violet Plant Food and Miracle Grow for Acid Loving Plants fit the bill, too. (Even though fertilizer is not "food." It's more like vitamins. Only the plant can make its food -- sugars and carbs from sun, water and air.)

 

7-7-7 means 7% each of the big three nutrients nitrogen, phosphorus and potassium.

7-7-7 means 7% each of the big three nutrients nitrogen, phosphorus and potassium.

Related links

  • Houseplants' spring revival
  • Simple watering guide
  • What's Up 71: Poinsettias, lichens, jade cut back, winter protection
  • Jade cold cut back