A very large genus of pretty, dwarf, stemless" plants that are all from temperate climates or high elevations. Those of us who have crossed the Atlantic will remember the fields and banks and hedge rows where the primrose covered the ground. The cowslip (P. officinalis) was not so common and was generally found in a colony in a pasture and the oxlip (P. elatior) was still less common.
Primula Obconica Grandiflora.
Many primroses are hardy with us, but our severe winter, and often hot, dry summer, are not nearly so favorable to them as the more temperate parts of Europe. The polyanthus, similar to the cowslip except in color, is the leading flower in thousands of cottage gardens, and with it the old woman's story that it you plant a cowslip or common primrose upside down it will come red, double, etc. This strange phenomenon never occurred in the garden that you are visiting, but it did happen, because our Aunt Jane or old Bill Jones did it many times.
The polyanthus is sometimes seen doing very well here, and where it can be shaded, but not in a wet soil, and protected in winter, it is a most charming hardy spring flower.
The old double white form of P. Sinensis was once a most important plant with every florist. Its flowers were used in immense quantities for making designs, but we have gotten over that, and although we had no difficulty in cutting up the large plants with a sharp knife and making each section into a cutting which rooted slowly but surely, we no longer bother with that method of propagation. We have now a double white equal to the old variety from seed and have every shade, double and single, from pure white to crimson. The varieties of P. Sinensis come true from seed and it is upon such we depend for our fall, winter and spring flowering plants, and they are now one of our most important plants.
Besides P. Sinensis we have P. ob-conica and P. Forbesii, the baby primrose. For some years we did not realize the great beauty and usefulness of P. obconica. It is a most charming and useful plant, and the baby primrose sells at sight. They are so profuse in bloom and have the great good quality that they are fine window plants, and being easily raised can be sold at a very moderate price. Other species may be found very attractive for the private collection, but the three mentioned are the leading commercial plants, and all want about the same treatment.
Always obtain the best strain of seed. It takes time and tedious care to save primula seed, so don't begrudge paying • for a good strain. The foliage as well as flowers of the P. Sinensis are handsome. We have fern-leaved, parsley-leaved, curl-leaved, and in flowers most beautiful colors and markings. The flowers of obconica have been greatly improved of late and doubtless in both that and Forbesii great improvements will be made.
The primulas are the least troubled with any of our greenhouse pests of any cultivated plants. The principal thing to remember is that they do not like much heat. After they have left the seedpan they need a good open soil; two parts loam, one part sifted cow manure, and one part leaf-mold will do them finely, potted only moderately firm.
The leaves, or rather, leaf stems, break easily and here is where careful and skilful potting comes in. I frequently see people, when asked to "knock out those plants," take hold of the top of the plant as they would a cat's tail if they wanted to draw pussy from her retreat. Get the base of the plant in the fork between your fingers, and you can protect every leaf. I noticed some years ago that the English florists had small sticks pushed down on three sides of the stem of the primula just after shifting, to keep them from wobbling about, as they were potted what we would call " high." We never found any necessity for that, for they can be potted with care just right, sufficiently deep to hold them firmly upright, but not by any means to bury their crowns. This is particular; don't get them too low, but just so that they sit firmly on the soil.
If you wish to have primroses by October you should sow in April, and if you wish to have them in spring you should sow again at the end of August. You can with care sow any time from March to September. We usually sow about May 1, which gives us flowering plants from November on to March, after which we think there are many other plants, not better, but the people want a change, and for an Easter plant we do not prize them. It is in early winter that they are such favorites with everybody.
The coldframe is an excellent place to summer over the primroses. With the glass shaded and the sashes raised back and front, it is cool, and if you will not neglect them there is no place in the greenhouse where they can be grown so well. If the frame is in the shade of trees so much the better. It is coolness you want.
Sow on some light loam and leaf-mold that has been previously well watered. Just press in the seed and cover with more leaf-mold very lightly; when the seed is out of sight it is covering enough. Place a pane of glass over the flat or pan and don't let the soil get parched. When the little plants are up keep the pan in the coolest place you have.
In five or six weeks they can be potted singly in 2-inch pots, using clean pots. 1 have found these little plants do finely on a shelf in a house that had a good shade. In another five or six weeks they will go into a 3-inch pot. If you don't have a coldframe, then give them a bench where it is shaded overhead, and they can get plenty of air. By the end of August or early September they should be shifted into their flowering pot. We sell most of them in 4-inch pots, and the great majority go as soon as one fine truss is developed, but to grow a fine plant they should have a 5-inch.
After the heat of summer is gone we try to keep them at about 50 degrees at night, but less won't hurt them in the least. And don't crowd them at any time; they must have full room for the spread of their pretty leaves, or they are useles. They need little syringing, and none when in flower, but when growing during summer a fine sprinkling does them good. They wilt quickly when allowed to suffer for want of water and need plenty of water from seedpan to flowering. The soil should be always in that condition that it will take plenty of water.
If you flower them as late as March or April their flowers will need shading.