Summary: Repotting plants in May gives the plant lots of time to put on new growth and mature during the spring/summer growing season. Soil for larger plants should be loose and drain well.
It’s potting time in the home 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. If all this seems quite a chore, remember that repotting pays big dividends.
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 and good fibrous soil. A potting bench or tray is almost a necessity in every greenhouse. It need not be large – 3 x 3 feet provides 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 4s which will take some pounding. The sides and back should be about 4 inches high. When made in this way, there will be no cracks in the tray floor where soil can sift through and soil will not spill off the edges.
Always use clean pots, not only as a precaution against insects and diseases, but so the root balls will come out easily 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 some bleach to the water to soak pots in for cleaning and then soak them in clean water to leach out any bleach. It is a good extra precaution and is no trouble. New pots (clay) should be soaked in water for an hour or more and then stacked to drain well before use.
Soil For Repotting
The soil for repotting large plants should be in loose, coarse particles so that it drains fairly well. Bagged potting mixes from the garden center work great! Fine soil packs tightly in large pots with the result that the water rests on top without penetrating the root ball. Young plants, however, require a fine, porous and more compact soil than they will need later. Look at an African violet mix.
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 so that you can pick one up as you scoop up soil with your right hand.
Repotting Small Plants
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. With very small plants it is easiest to fill the new containers to the surface and make receiving holes in the soil with a plant tag, dibble or pencil. I always feel that small transplants take the shock of moving better if they are kept on the dry side for a week or ten 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.
Repotting Larger Plants
When large plants in 12-inch or larger pots and tubs need replanting, it doesn’t pay to try to save the containers. If you try to lift such plants from their pots, root damage is almost certain. Even though large containers are expensive and scarce, it is much better to break and destroy them than to harm good plant specimens. The fact is, you will often find that the roots of a plant that has not been moved for several years are imbedded in the clay and plastic ones sometimes are bulging.
When repotting such plants, gently scrape off any old dead roots on the outside and replant in a container of the same size or one or two sizes larger.
Set the plant in the new pot and work soil around the roots, adding it a little at a time. The soil should be tamped quite firmly with a potting stick (i use a old handle from a hammer) to fill all spaces in the pot.
Timely Tips For Winter Blooms
Several good fall and early winter flowering plants may be started from seed now. These plants will be especially important if you want a succession of bloom right after the outdoor things are gone. Sow seeds of asters, fibrous-rooted begonias, calceolarias, cinerarias and primroses (Primula obconica). The seed will germinate well at this time of the year and will give you husky plants before hot weather sets in.
Asters started now should be in bloom by September. 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; a cellar is a good place to get it started. Plants flower in December. Primula obconica can be had in bloom before Christmas. Remember that it does not like peatmoss.
by C Ernest
