Flowers are vital for the garden for lifting our spirits and bringing pollinating insects in. Diversity is everything. It is a true expression of the health of the garden.
Sweet peas tick many flower boxes – pretty, lovely scent, easy to grow, long lasting, very good in vases. The list goes on.
The hassles are that they need a support system to grow up because they are climbing plants and they are beloved of slugs when you first plant them out. Keep your eyes peeled.
The good far outweighs the bad and once you have grown your own sweet peas whether one plant in a pot or loads in a long row or round a teepee in the garden you will be back for more every year.
Being in the legume family and therefore related to all other peas and beans, sweet peas provide their own nitrogen and feed themselves once they re growing strongly. They have a real urge to grow and as such are very willing germinators. All sweet peas must be sown in pots and then transplanted into their final resting place when the time is right.
You can sow in the late October for a late spring/early summer crop grown indoors (in pots in a warm sunny room) or sow in spring for a summer crop grown outdoors.
Choose any size plastic pot from 9cm to 3 litre and fill to just below the top with any good garden soil or bagged compost. They are not fussy they just need somewhere to germinate. Firm the compost gently, water and then after the water has drained through and the soil surface is left damp place each seed 2cm apart. 5 seeds to a 9cm pot, 12 to a 2 litre pot. Sprinkle soil or compost over the seeds until they are covered. Water again and place in a warm, light place to germinate.
A trick I use is to soak the seeds in warm water for 4 hours before I sow them. Do this in the morning and sow in the afternoon. It helps break dormancy. All seeds are dormant inside their tough shells before they reach soil or compost when they get the message to come to life. Ones with very hard shells like sweet peas benefit from a little extra help.
The green shoots of the seedlings will appear within a fortnight. Keep them well watered. Autumn sown plants then need to spend the winter outdoors, covered from heavy rain, and then brought back inside at the end of January.
Leaving them outside slows their growth but means that as the days begin to stretch in February they start growing again. They will flower much earlier than plants that are sown in March.
Sweet peas sown in the middle of March will be ready for transplanting by the beginning of May when the soil is warming up in the garden. They are tough and will even be able to withstand a little frost if a late one comes in May but they like warm weather to really start growing, so do not be tempted to plant them out in mid-April even if they seem ready.
By May you should have a small plant in its pot with two, if not three shoots. Despite what you may read elsewhere do not pinch out (shorten) any of these shoots. Plant the whole plant out as it is. (See below under Planting Out).
A spring-sown crop needs to be ‘hardened off’ before being planted out. This is the process of acclimatization that I explain in all writings about flowers and vegetables that start life inside and end up being planted outside.
If you plant something outside straight from the warm polytunnel or greenhouse or kitchen window sill without letting it feel what conditions are like out there first, it will get a huge shock and may even die. Cabbages and tomatoes literally turn blue if they are not hardened off properly and a lot of the more tender vegetables like French beans simply will not grow properly, remaining stunted and weak.
So one week before planting your sweet peas out you should bring them outside for a few hours and then a few more hours the next day, until by the end of the week you leave them out at night and after a couple of nights out they will be ready to plant.
Preparing the soil
The best way to grow sweet peas in the garden is up a teepee of 8 or 9 bamboo canes or hazel poles of similar thickness. They need to be 2.5m in length and driven at least 20-30cm into the ground so that they are stable. They should be spaced 30cm apart in a circle which takes up about one square metre of space. Drive them at an angle so that they gather easily at the top where you tie them together with tough twine.
The soil should have all the weeds removed and two buckets of homemade compost added. This can be laid on the surface. No need to dig it in.
If you are growing them in a pot use a minimum of 30cm diameter pot and get three tall canes in. For compost use either good garden soil or a 50:50 mixture of potting compost and garden soil.
Plant one sweet pea at the base of each cane. If you have followed my advice you will have several plants in the pots in which the seed was sown. You need to tip them out gently and disentangle the lovely, white fleshy roots from each other. Don’t worry that the soil falls away. This will not trouble them.
Plant firmly into the ground and tie at least one of the shoots to the cane. A little bendy piece of wire called a calyx ring is perfect for the job; a short length of string will do just as well.
The other shoots need to be propped up by twigs so that they are not sprawling on the ground and vulnerable to slugs. The best way to arrange this is to get hold of some other twigs that you can push into the ground between the bamboo canes. These will be very good supports for the other shoots to cling to. And they will do this as they grow because they have their own climbing mechanism in the form of tendrils; little curly shoots that cling on to supports.
If you have spare plants and a good source of twigs you can also plant one in the gap between the main canes of the teepee.
Once planted give them a good water as this settles the soil around the roots.
Depending on what the weather is like the plants will take a week or so before they start growing properly. If it is wet the slugs will come and you must go out at night with the torch and remove them. Baits and pellets, even organic ones, don’t work and are a waste of money and time. However at the beginning of the season you have a chance to reduce the breeding population of slugs in your garden by removing them because there are not that many around.
Because the plants are self-supporting all you have to do is to tuck them in towards the cane now and again. Essentially they will hang on to each other.
By the time the plants are chest high they will start flowering. The important thing now is to pick and keep picking. The more you pick the more flowers will come.
As the summer goes on and the plants reach the top of the canes some of the flowers that get left behind will go to seed. This is good news because you can save these seeds for next year. Wait until the pods go brown and papery and then harvest and put in a warm sunny place to dry. Pick out the seeds when they are dry and hard after a few weeks.
After that you can remove the crop and put it on the compost heap. Take the canes away, tie them up in a bundle and store them in the dry for the winter and use the small twigs for kindling.
We are spoiled for choice. There are old-fashioned varieties that tend to be smaller flowered and heavily scented and modern Spencer types with frilly edges, huge flowers and not such intense scent. Anything labeled ‘Exhibition’ or Spencer is not suitable for autumn production.