21. Propagate by seed sown as soon as the seed is ripe into a cold frame . 22. The name itself exemplifies the distinction between the warm greenhouse and the unheated cold frame . 23. These include various row-covering techniques, such as using cold frames and garden fabric over crops. 24. Only about 90 different species made it to adulthood from the greenhouse and cold frames . 25. A miniature greenhouse is known as a cold frame . 26. Today, tobacco is sown in cold frames or hotbeds, as their germination is activated by light. 27. Between them are the foundations of cold frames . 28. They are best germinated using a cold frame . 29. It therefore must vary in hardiness, less hardy forms could be grown in a cold frame . 30. Seeds are then sown in containers in a cold frame in autumn, or between September to May.
