Seed sowing dates This week I thought it might be helpful to include some more detail on seed sowing dates as, with some minor planning, you can skew the season in your favour and avoid some common pests or diseases. Some plants prefer hot weather, others prefer cooler conditions, the more comfortable we can make them, the better they will grow with higher yields and fewer problems.
Broad Beans As you know, broad beans are one of the earliest crops you can grow in the garden but there is also sense in sowing early. Beans sown the previous Autumn or in February (in modules and planted out is best) will have produced good harvests before the common broad bean disease, chocolate spot, hits in Summer.
Brussels Sprouts While this has nothing to do with pests or disease, I thought it was worth mentioning that sprouts have 3 main sowing dates depending on when you want to 'enjoy' them. For early winter sprouts sow mid March undercover and plant out in late April, for Christmas sprouts sow in early April indoors and plant out in May. If that isn't enough sprouts for you, a third sowing in early May and planted out in early June will give you a late winter harvest up to March the following year.
Carrot Once you have your soil right (light and easily worked, no stones) carrots are relatively easy to grow apart form one thing - the carrot root fly. If you are growing organically the only option is prevention rather than cure which means covering your crop with an insect protection mesh.
Sowing times can also help as their are usually 2 generations of carrot root fly (sometimes 3 if we have a warm Autumn) in a season, the first being late April and early May. Sowing carrots in the last week of May will likely miss the first generation of the root fly and will also germinate and grow quickly in the warm soil. The advice on seed packs usually suggests April for the first sowings but holding off has its advantages.
Celery Celery has a reputation for being a difficult plant to grow, or at least to grow well. There are two important things to remember; celery is originally a marshland plant so needs a lot of water and it is best harvested when just mature or it will get tough and stringy.
It is better to sow small amounts over a period from late March to late May to give a supply of 'just mature' plants over a longer period. Also, if you live in an area with dry summers (I wish) or have a very free draining sandy soil later sowings might suit you better as the celery will mature in late summer and early autumn when there is more moisture about.
Onions They say that onions are one of the easiest crops to grow. This is true, especially when grown from onions sets, but they can bolt (run to seed) in some years depending on how the spring turned out.
Onions are a biennial, meaning they have a two year lifecycle where they produce a bulb in year 1 and a flower in year 2. Onion sets are immature onions that were lifted the previous autumn when they had reached the size of a cherry and stored indoors for the winter. When we plant them out again in spring we are basically fooling the onion into thinking it is still in year 1 of its lifecycle.
If onion sets are planted too early and are exposed to frost for a prolonged period the game is up (they will realise winter has passed) and they will move to year 2 of their lifecycle and produce a stem and a flower. For the best chance of avoiding bolting, delay planting sets until the end of March (mine will be going in next week).
Oriental Salads Oriental vegetables cover a huge range of crops including Pak Choi, Tatsoi, Rocket, Mibuna, Mizuna, Leaf Mustard and Komatsuna. All of these brassica salads are keeping an eye on the number of daylight hours in the day and, once their threshold has been reached, will run to seed.
It is better to avoid summer growing altogether and sow either in early spring for spring harvests or in late summer or early autumn. In general they are a very cold tolerant group so are ideally suited to the cooler parts of the year.
Peas Nothing says summer more than fresh garden peas, they are one of my favourite vegetables. In my experience they will almost inevitably suffer from powdery mildew in mid to late summer (a grey/green powdery substance on the leaves) which slows production and eventually kills the plants.
If peas are sown in early to mid April they will have produced multiple crops (you need to keep picking them to encourage the vines to produce more peas) by the time the disease hits in late summer. Later sowings will be more at risk.
Purple Broccoli Purple sprouting broccoli is a treat at any time but is at its most valuable in February and March when there are few other crops in the garden. The common mistake is to sow too early which results in Autumn harvests or plants that have got too large to survive a hard winter. Unless you want purple broccoli in Autumn, the best time to sow is mid June for harvests early the following year.
Cucumbers, melons and courgettes We have has a lot of queries on social media about cucumber plants, usually about seedling care in March. I'm usually thinking noooooooo! when I read that people have sown cucumber so early as they are very susceptible to cold (the cucumbers, not the people). When conditions are right (warm enough) courgettes and cucumbers grow like wildfire whereas they really struggle in the cold so there really isn't any advantage to starting them off early.
I would sow courgettes in late March at the earliest for planting under cover, mid to late April for growing outside. For melons and cucumbers I would wait until mid April or May.