If you're looking to add interest, colour and stunning scent to your garden this summer sweet peas are the answer.
Every year sweet peas are a constant in our garden and farm, they can be trusted to climb up any frame work nearby all while producing fragrant flowers. But how can you get the most out of your sweet peas?
Sweet peas have to be some of the easiest seeds to collect from plants from the previous year. Starting by allowing spent flowers to form a seed pod, (similar to an edible pea pod) as time goes on the pod will become plump with seeds, it will turn brown as the season goes on. Let it turn brown and once it has become almost dry to the touch pick it and open the pod to access the large brown seeds. Pop into a little paper bag or envelope and keep it in a dry cool dark place until it is time to sew them.
We start off our sweet peas in late December to mid January on our heated bench in the potting shed. We pop one seed into a single module in our seed trays and barely cover over with compost. We do hear of people soaking their seeds beforehand but we never have had to do it and our germination rates have always been high.
On the farm here we have to remove our seedlings off the heated bench once they have poked their heads through because of how our potting shed lighting is. But even when we move them to our poly tunnel table the little plants do not seem to mind. A truly tough plant, exactly what we need! When the seedlings are just about 2 or 3 inches tall we pinch out the leader tip, this is simply just the growing tip. You need to be quite brutal and go down even as low as the last pair of leaves (do not worry they are resilient and it will make the plant so much better, tough love!). Below is a photo of the decapitated growing tips from last year. 
At this point in the sweet pea's life we transplant them into 9cm pots, two per pot usually but you can also pop in a third. This is the last time we will really pay much attention to the young plants until it is time to plant out. All you need is any structure to plant them by, with their tendril growing habit you will need some wire or twine for them to cling to, even some thin bamboo/ pea-sticks for them to hug would be fine.
Below you can see that we often make teepee shaped forms for sweetpeas. Just 4 outer sticks, one stick in the middle and twine woven all the way up the teepee about an inch width between rows to ensure the tendrils can grab the next row as they climb.
Sweet peas are such vigorous annuals, they will thrive almost anywhere once they are watered regularly and feed once every 10days. To maximise the flowering season be sure to deadhead regularly, this will encourage more and more flowers to be produced.