Growing Strawberry Plants in the Greenhouse
If you would like to have greenhouse-grown strawberry fruits ready for picking by the end of April, which is at least a month before outdoor-grown plants will be fruiting, you can do so by following these tips:
Select your plants in the spring from the strawberries growing in the garden and remove their blossom to prevent fruiting and ensure the production of strong, early runners. Inspect the plants regularly during the spring and summer and if there are any signs of virus or disease discard the affected plants immediately.
The first runners will usually be ready forby the beginning of July. The young plantlets should be pegged down in 3-1/2-in. pots filled with a mixture of equal parts of loam, peat and sand. Not more than six runners should be used for propagation purposes from any one plant. The plantlets are secured to the with pieces of bent wire.
Keep the plantlets well watered and when they have rooted sufficiently, sever the runners from the parent plant. This stage should have been reached by the first week of August.
By the end of August the plants should be potted on into 6-½- or 7-in. pots – the plastic kind are good for this purpose – using the John Innes No. 3 Potting Compost. They are stood in a cold frame until mid-January when the first batch should be brought into the greenhouse heated to a temperature of at least 4°C (40°F). You can grow 36 plants in this way in three batches of 12. When the first batch of 12 plants are in flower, bring the second batch of plants into the greenhouse and the same routine is followed with the third batch to provide a succession of fruits.
To return to the first batch of strawberry plants, when these are housed in the greenhouse they will slowly begin to produce new leaves and, not long after that, open their first flowers. Eventually, the aim should be to have only ten flowers on each plant, thinning them out to leave the best, but it may be prudent to delay the final thinning until the fruits have set. The growth should be supported with raffia tied to stakes so that the developing fruits do not come in contact with the pots or compost, as this might damage them.