Cuttings from many annual plants will keep over winter, sprout roots, and be ready for planting in spring. You may place them in pots or cups without drainage filled with moist perlite or vermiculite. Locate them at first in bright light, away from the sun. Move later to an area where they receive morning sun.
Loosely cover with an open plastic bag to increase the humidity around your cutting. Water often enough to keep the soil evenly moist, but not soggy. Plant rooted cuttings in a well-drained potting mix, move to a sunny window and care for them as you would your other houseplants.
Most cuttings taken in spring will be flowering in their first summer. Those taken in late summer will be overwintering under glass and be ready to harden off during May. One of the keys to overwintering rooted cuttings under glass is to keep them on the dry side in bright frost-free conditions of around 7°C (45°F).
Cover the pot with a clear plastic bag held in place with a rubber band or similar around the pot, to keep the compost moist. Place the pot on a well-lit position indoors, but out of direct sunlight. Keep compost moist and your cuttings should root in six to eight weeks.
In two or three weeks the buds will open, but the plastic bag should keep humidity around the leaves high and prevent excess water loss. Make sure the pot is in a bright spot, that it does not overheat, and that the rooting mix is moist but not waterlogged.
Keep your cutting humid by loosely wrapping it in clear plastic. You can also create a makeshift greenhouse by placing the entire pot in a clear plastic bag. Place your planted cutting in bright light but avoid direct sunlight which can be too powerful.
Cover the Pot With Plastic
Place the container with the cutting into a plastic bag. The bag will keep the humidity high and hold in heat. Do not seal the bag completely because some airflow is necessary to prevent fungal rot.
It will slow transpiration while the necessary components are used at the root sites to build a new root structure. Keep the atmosphere around the cutting warm (not hot), keep the humidity relatively high (>90%), and keep the root zone temperature warm (at about 25°C).
Media is usually kept at 72-77° F while air temperature is maintained at 68-73° F. If bottom heat is not used, air temperature should be maintained between 77 and 80° F. Maintaining air temperatures lower than medium temperatures retards shoot growth while promoting root development. Excessive heat can damage cuttings.
Storage of cuttings
It is best to harvest cuttings in early spring and plant immediately but if this is not possible, cuttings can be stored safely for about 4 months. Store cuttings in a cool, dark, and moist place.
Hardwood cuttings provide an easy and reliable method of propagating a range of deciduous climbers, trees and shrubs, and as bonus, they are taken from mid-autumn until late winter when more time is usually available to the gardener.
Herbaceous cuttings can be taken throughout the growing season (spring to late fall), while softwood cuttings should be taken in spring or early summer. Cuttings can be taken as long as the parent plant is healthy and in active growth.
Propagating plants in winter does take a bit longer than in the summer, two to four months for roots to develop, but it's a great way to get free plants from winter prunings. Providing bottom heat will speed things up a bit, but isn't necessary.
Cuttings may be soaked in cool/cold water from 24-48 hours directly before planting to improve survivability. On site, the cuttings should be stored away from direct sunlight, heeled into moist soil, or stored in water until planting. Do not have cuttings in water for more than 4 days.
You can propagate houseplants at any time of year. This being said, the best time to do it is during their growing season – which is typically spring-summer. They will grow more slowly during the dormant months of autumn-winter.
Technically, you can transfer your cuttings to soil at any time. In fact, you can actually propagate directly into soil, however, it's much harder to do within your home. When you propagate in soil, you have to keep a good balance of soil moisture, air flow, and humidity.
Warm growing medium temperatures accelerate cell division which leads to faster callusing, root initial development and subsequent root growth. It also speeds up the dry-down rate of the growing medium, which also helps encourage better rooting. The best way to warm the growing medium is through bottom heat.
And they tend to rot if you don't wait for the cutting to form a callus, a hard, dry “crust” at the base of the cutting. That can take anywhere from a few hours to a few weeks, even a few months in extreme cases. In general, the thicker the stem, the longer it takes to seal itself off.
With the exception of succulents, most cuttings need high humidity in order to grow properly. Until cuttings develop roots, they are very susceptible to drying out. If you don't have a bright area with high humidity, you can create a humid environment around the cutting by placing a clear plastic bag over it.
Cuttings can take in water from the air through pores in the leaves called stomata. To trap humidity, plant your cuttings in wet soil, use a spray bottle to mist the leaves, and cover them with clear plastic as described before. Then, place your cuttings in a warm spot.
In general, the rooting medium should be sterile, low in fertility, drain well enough to provide oxygen, and retain enough moisture to prevent water stress.
Give cuttings bright light but not sun. Keep soil moist but not wet. The cuttings should root within three weeks. Admit air gradually to wean the cuttings from their humid environment, then pot singly before outdoor planting.