About petunia varieties - in the article Petunia: modern varieties
Petunias are sown from February to the end of March. Previously, ampelous forms with a long cascade are sown, otherwise they will not have time to increase the required volume. Small-flowered forms bloom the fastest, so they can be sown later. For sowing, you need to use small bowls or pots with holes at the bottom, at least 7 cm deep.If the holes cannot be made, then you need to pour a drainage layer at least 2 cm.If the drainage layer is not done, then the seeds or seedlings can be ruined by excess moisture in the substrate ... Sometimes in packages they sell seeds in a special shell or pelleted. Ampel petunias are almost all in the form of balls. These balls are easy to spread evenly over the surface of the substrate. Therefore, it is better to sow them immediately in seedling pots, which will allow the seedlings not to dive in the future.
The next stage is the land for sowing. For small petunia seeds, it should be loose and moisture-absorbing. Until recently, flower growers were advised to prepare soil mixtures themselves, therefore, in the literature, the best compositions of soil mixtures for sowing are still rewritten from previous books. Now in any flower shop you can buy a ready-made mixture. (About high-quality soils for sowing - in the article Sow me with love). But other problems arose. Often, shoots that appeared together begin to die or grow poorly, although all the conditions for their growth are met.
The first reason is the high acidity of the substrate. In modern mixtures, the main component is moor, not completely decomposed peat, which can be acidified. Typically, lime is added to the mix to neutralize the high acidity. But it is outwardly impossible to distinguish a neutral substrate from an acidic one. This can be done using a special litmus paper available at gardening stores. Soil acidity (pH) for petunia should be 5.8-6.0. The second reason is the high salt content. This happens when soil from greenhouses is added to the mixture, where vegetables were grown with a large amount of fertilizer, or the fertilizers added to this mixture were poorly mixed. This becomes noticeable when the substrate dries up and a white bloom appears on it.
To avoid buying a bad substrate, it is better to choose special earth mixes for sowing from well-known companies. Stir the soil mixture thoroughly before filling the containers, adding disintegrants and moisture retainers such as perlite or vermiculite, which will facilitate maintaining the desired moisture content in the substrate.
The containers are filled with the finished substrate the day before sowing. A small layer of substrate is poured over the drainage and compacted, but not to the state of "asphalt". And already on this layer, a second layer of substrate is placed, which for the smallest seeds it is very desirable to sift through a sieve. After pouring this layer, 0.5-1.0 cm should remain to the edge of the container. The surface of the last layer is leveled. The container prepared in this way is carefully but abundantly spilled. If the container has a hole at the bottom, then it is placed in a pallet and 1-2 cm of water is poured into it.
The next day, without watering the soil, they begin sowing. The most difficult thing when sowing is to evenly distribute small seeds over the surface, so that it is not where it is dense, and where it is empty. With uniform sowing, there is a greater guarantee of avoiding the "black leg". Even seedlings are obtained if the seeds are mixed with washed and dry coarse sand. But the best results at home can be obtained by sowing seeds mixed with sand in the snow. To do this, snow is poured into the container with a thickness of 1.5-2 cm. Of course, it must be loose, otherwise an uneven surface will turn out and, accordingly, the same sowing.The pelleted seeds are laid out with a stick, to which they easily stick if they are slightly moistened by placing it on damp ground. The most important thing for the seeds prepared in this way is that the shell is immediately soaked and melted. Therefore, the substrate must be very wet before sowing, or they must be heavily sprayed with a spray bottle.
The sown seeds are not covered or powdered with a thin layer of vermiculite, but if they were sown without snow, they are sprayed with a solution of a growth stimulator. It is not recommended to process seeds in dragees with stimulants, since the shell contains everything for normal germination and initial growth, including growth substances. Then the container with seeds is covered with glass or inserted into a plastic bag. It is imperative to put a label if different hybrids are sown, and also write the sowing date so that you know when the seedlings will appear.
Covered containers or pots on pallets are placed in a warm place with a temperature of 22-25 ° C, and a light one is better. Before sprouting, you need to maintain soil moisture by spraying it when it dries or adding water to the pan. Glass and film must be turned over at least twice a day. At an even temperature, seedlings will appear in 5-7 days. As soon as the seedlings bite, it is necessary to put them in the brightest place and slightly reduce the watering so that the substrate is moistened, and not wet. When the cotyledons unfold, you can gradually remove the glass or film. To do this, they are first raised or slightly shifted, and only after 3-4 days they are removed completely.
Seedlings of March sowing, with fully expanded cotyledons, can be placed in a greenhouse in a country house or on a loggia, since now they need a temperature of 18 to 22 ° C for growth. The moment of growth of the cotyledons and the first leaf is the most difficult in the process of growing seedlings. At this time, a lot of light is needed so that they do not stretch out, and sensitive watering so that they do not suffer from waterlogging and do not die from fungal diseases. Poor drying, of course, not to the point of wilting, allows the roots to grow better in loose soil. Then, when the seedlings take root, they will grow the leaves faster. If, nevertheless, the seedlings began to die from excess moisture, then the soil can be covered with a thin layer of dry sand or fine vermiculite.
After 2-3 true leaves appear, the seedlings are ready for picking. Previously, you had to dive only if the seedlings began to die from the "black leg" or thickened crops turned out. If the seedlings sit sparsely, not elongated, then you can dive later, since the petunia easily tolerates transshipment and with a large number of leaves. You can dive into seedling pots or directly into a balcony box and a hanging basket. It is better to immediately place ampel petunias in a basket, since their roots grow very quickly, and in seedling pots, after 3-4 weeks, they begin to lag behind the plants planted in containers.
The substrate for picking is the same as for sowing, but for pots you can not use baking powder, but add slowly dissolving fertilizers. More fertilizer is added to the soil for balcony boxes and baskets, as well as perlite or other leavening agents. At the bottom, it is necessary to pour drainage in a layer of 3-4 cm. Ampel petunias in containers, if they are located at the edge, are planted with an inclination of approximately 45 ° from the center of the container. In this case, they hang down faster and cover the sides of the container.
Immediately after picking, the seedlings are kept at a temperature of 20-22 ° C for 1.5-2 weeks, then they can be placed at 16-18 ° C. With this mode, the plants are more compact. At high temperatures and poor lighting, the seedlings stretch out, take root less well in the open field and bloom weaker. Watering during this period should also be done in moderation. It is imperative to feed so that the seedlings are healthy and then bloom profusely. Fertilizers are best added to the water when watering. You should start feeding with very small doses when the first leaf unfolds.It is better to feed with fertilizers with nitrogen and potassium or calcium, and then with complex fertilizers, where there is more potassium than nitrogen.
In some petunia hybrids, already in large seedlings or in plants in baskets, first yellow veins appear on the leaves, then the entire leaf turns yellow. This is a clear sign of iron deficiency. To return the plants to a healthy look, you need to sprinkle them or add iron chelate or Ferovit to the soil 1-2 times, in the dose indicated in the instructions.
Another important technique when growing ampel petunias is pinching. The first pinching is done when the shoots are 7 to 10 cm long. The earlier it is done, the more lateral shoots are formed. The second pinching is performed when the shoots are more than 10-15 cm long, removing the very end of the shoot so that the already laid flower buds remain. In the future, you can pinch only strongly grown shoots, for uniform growth of the bush.
When the roots appear from the bottom hole of the pot, this means that the seedlings are ready for planting and in May they can be planted in a flower garden or container.
Read also the article Modern approaches to growing quality seedlings