Raspberries are from the same family as roses, so they need a similar cold stratification. Soak your raspberry seeds in tepid (room temperature) water for 24 hours before planting. For raspberries, it is probably easiest to start them in separate containers with moist soil - these can be individually bagged to retain moisture. Keep the seeds in the fridge UNTIL you see sprouts, then the container can be moved to a warm and sunny location until the seedling is large enough to be transplanted outdoors. The seeds may be in the fridge for 4-6 months, so if you’re in the middle of the summer heat, wait until fall to plant your seedlings outdoors.
Outdoor planting location depends on a variety of factors. Raspberries do not do well in high heat, but if they are shaded through the summer and get sun in spring and fall, you can get two crops if you live in the south. Where summers are not so harsh, full sun year round is necessary. Ensure that your planting location is a) permanent (unless you plan on keeping them in containers) and b) that your location has not been used to plant anything from the nightshade or rose family within the last few years - this is mostly to prevent cross contamination of common diseases, funguses, etc that would spread to your new plants.
Raspberries will often not produce fruit their first year due to not enough “chill hours” - a chill hour is when the temperature is between 37-50ºF, and most varieties of raspberries require at least 800 hours. If you experience an extremely mild winter, your plants may flower, but won’t have the stored energy to actually produce fruit that year.
How to Maintain Raspberries
Make sure to clean your tools before and after use, and make your cuts at 45º angles. Always cut back broken, dead, dying, or diseased branches. Also prune at the base to allow air to the base of the plant and to make it easier to water only at the base of the plant. Prune just before dormancy periods end, when the leaf buds begin to swell. Get your pruning done once the swelling starts but before they break open. If you wait too long, wait until the next dormancy to prune. Consider a drip irrigation system to help prevent fungus. Keep the largest thorns trimmed back to help you when working around the plants. Raspberries have lots of small thorns as well, so wear gloves. If your canes bore fruit the previous year, they usually will not bear fruit again and can be pruned, especially if they have turned grey. Keep your raspberry as a bush so that it’s more manageable. Be aware of suckers that can grow from the roots. Raspberries can be considered invasive if they get away from you.
Raspberries are actually an aggregate fruit, this means that all of the ovaries must be fertilized to have a properly developed fruit. If the fruit is improperly formed, it may not ripen. To harvest raspberries, you can either snip the berry with the cap, and remove those later, or you can hold the stem in one (gloved) hand and gently twist the berry to remove it from the receptacle. Be sure not to squeeze the berry or you could break some of the fruit.