It’s potting time in the greenhouse.
Large plants, particularly those which have flowered and will be grown on for several years, need either top dressing with fresh soil or shifting to larger pots.
Roots of smaller plants may be crowding their quarters, in which case the plants should be moved to larger containers.
Rooted cuttings should be transferred from the propagating bed to pots of good soil where they can take up moisture and continue growing.
Remember that repotting pays big dividends if all this seems quite a chore.
Necessary Materials
Of course, any job will be easier with a handy place to work and a good supply of the necessary materials.
You’ll need:
- Pots of various sizes, from 3 inches up
- Seed flats or shallow boxes
- Good fibrous soil
Potting Tray
A potting tray is almost a necessity in every greenhouse.
It need not be large—3’ x 3’ feet provide enough working space for the small greenhouse.
A tray can be made to set on top of a plant bench or to fit between two benches over a walk.
It is portable and can be stored when not needed. The bottom of the tray is of heavy plywood, braced with 2 x 4, which will take some pounding.
The sides and back should be about 4” inches high. When made this way, there will be no cracks in the tray floor where soil can sift through, and soil will not spill off the edges.
Pots
Always use clean pots as a precaution against insects and diseases so that the root balls will come out quickly at the next potting.
If old, dry soil is left clinging to the sides of a pot, it is almost impossible to remove the plant later without disturbing the roots.
I usually add 35% percent formaldehyde to the washing water at the rate of 5 tablespoons to a gallon of water.
It is a good extra precaution and is no trouble.
New pots should be soaked in water for an hour or more and then stacked to drain well before use.
Plant bands set in a seed flat are excellent containers for small transplants since they are so compact and fit snugly in the flat.
Ideal Soil
The soil for repotting large plants should be in loose, coarse particles to drain pretty well.
Fine soil packs tightly in large pots with the result that the water rests on top without penetrating the root hall.
Young plants, however, require a fine, porous, and more compact soil than they will need later.
Follow Proper Potting System
When you have a lot of plants to handle, you’ll find that work goes faster with a system.
Stack the pots on the left side of the bench to pick one up as you scoop up the soil with your right hand.
Small plants should always be repotted before their pots become overcrowded with roots.
When permitted to become too pot-bound, the plants often become so starved and stunted that they can never again make sufficient root growth or take up nourishment and may just as well be discarded.
It is easiest to fill the new containers to the surface with tiny plants and make receiving holes in the soil with a plant tag or dibble.
I always feel that small transplants take the shock of moving better if kept on the dry side for a week or 10 days before transplanting.
Of course, the soil should be well moistened before lifting the plants so that a good quantity of it will adhere to the roots.
When large plants in 12-inch or larger pots and tubs need replanting, it doesn’t pay to try to save the containers.
Root damage is almost certain if you try to lift such plants from their pots.
Even though large containers are expensive and scarce, it is much better to break and destroy them than harm good plant specimens.
You will often find that the roots of a plant that has not been moved for several years are embedded in the clay.
When repotting such plants, do the following:
- Gently scrape off any old dead roots on the outside and replant them in a container of the same size or one or two sizes larger.
- Set the plant in the new pot and work the soil around the roots, adding it a little at a time.
- The soil should be tamped quite firmly with a potting stick to fill all spaces in the pot.
Timely Tips For Successful Blooms
Several good fall and early winter flowering plants may be started from seed now.
These plants will be essential if you want a succession of bloom right after the outdoor things are gone.
Sow seeds of the following:
- Asters
- Fibrous-rooted begonias
- Calceolarias
- Cinerarias
- Primroses (Primula obconica)
The seed will germinate well at this time of the year and give you hardy plants before hot weather sets in.
Asters started now should bloom by September, while Begonias will make good 4-inch pot plants by July and will flower all winter long.
Calceolarias take longer to mature, but you will be glad to have them in flower next spring.
Cineraria seed will germinate best at cool temperatures, and a basement cellar is a good place to get it started. Plants flower in December.
Question: A cineraria plant was given to me, and I would like to know how to care for Cineraria plants.
Answer: A cineraria must be potted in a well drained soil that will take heavy and repeated waterings. Overwatering in poorly drained soil will cause the plants to appear wilted. Water often and when the plant has lost its attractiveness, throw it away. New plants are grown from seed each year. They cannot be kept long after they reach full bloom.
Primula obconica can be had in bloom before Christmas. Remember that it does not like peat moss.