Caption: Bolting lettuces
Caption: Flowering Kale
Garden writer and soil ecologist Becky Searle of Sow Much More explains...
We put our time, effort and love into growing crops in our gardens and allotments, and anything that stands in our way of enjoying those crops can be very frustrating! Bolting is a term used to describe plants that go to see prematurely. Often these plants are setting seed before we want them to, but it’s not necessarily premature for them. Many crops have short life-cycles and going to seed happens towards the end of their life cycle, whether we like it or not! When plants start to produce flowers and seeds very quickly however, this can be a sign of stress. We must learn to listen to our plants, and accept their natural processes.
All plants (except spore-producing plants such as ferns and mosses) produce seeds. They are “programmed” to do this either regularly throughout their lifecycle or at the end of their lives. It is how they survive into future generations, and how they grow populations and disperse. Setting seed is part of a plants’ survival mechanism. Some plants are very short-lived and can go to seed after a just few weeks. If they fail to make seeds, they will not be superseded (excuse the pun) by the next generation. This is how we can keep on top of annual weeds in our garden, by catching them before they go to seed. More long-lived plants depend on seeds for their future generations too. Some trees are known to “suckle” their young by feeding carbohydrates through the fungal network to their progeny. When the parent tree finally dies, the young tree is there, strong, and healthy, ready to grow up and close the canopy. This helps to protect the other trees around it from wind that can get into gaps in the canopy and cause trees to fall, creating more gaps.
In periods of stress such as high temperatures or drought some plants will opt to set seed more quickly. This is because in their seed form, plants are incredibly hard-wearing. The outer shell of a seed (the seed coat) protects the embryonic plant within, waiting for environmental queues such as moisture, warmth or light to germinate. You can think of seeds as being like a life raft for the plants. When they need to go into survival mode, they jump into their life rafts and can sit there for a very long time if they need to. One particularly plucky seed was recently germinated after being held under artic ice for some 32,000 years!
So, we mustn’t begrudge plants when they decide to go to seed, or bolt. But we can learn from their experience. For example, we might feel that we have given them plenty of water, but if they’re bolting prematurely, they are almost certainly telling us otherwise. If they are in full sun all day, and bolting quickly it may be that they are too hot. Planting them near to some shade such as a shed or tree that will provide shade for a few hours in the afternoon can drastically improve your success with these plants.
However, we mustn’t forget that going to seed is part of a plants’ natural life cycle. When plants get to a certain maturity – which differs depending on the plant – it will naturally go to seed, regardless of the conditions. This is a wonderful opportunity for us to collect seed for next season. Leaving just one plant can give you plenty of seeds and free up space in your vegetable patch. By succession sowing things like Spinach and Lettuce you can ensure you have a continuous supply throughout the year, simply replacing old plants with new ones when the time comes.
How can I stop my plants bolting?
The short answer is you cannot. You can delay them going to seed, which is almost the same thing, but you cannot stop it from happening entirely. Here are a few things we can do to get the best out of our crops and delay bolting:
Mulching with something like Lakeland Gold is a brilliant way to lock moisture into the soil. It is super absorbent on the surface, so it allows water through, and then forms a sort of crust that stops water being lost through evaporation. It also feeds organic matter to the soil life who in turn help to improve soil structure. The soil structure is built by organisms moving through the layers of the soil, incorporating the organic matter and secreting sticky glues. These glues help to stick tiny particles in the soil together opening up pores so that water can travel down through the soil. The particles that are held together with sticky organic glues then hold onto water well, helping our soil stay moist but well-aerated.
Watering regularly can help to slow down bolting. To encourage deep-root growth you should give your plants a good soak, and leave them for a few days before watering again, as opposed to watering little and often. Of course this isn’t advisable in warmer temperatures where plants will need to be watered deeply and often! Ensuring that you have enough rainwater saved in your garden will help greatly if you need to water during a hosepipe ban.
Whilst you will need to get the trees established with regular watering, trees can provide wonderful, dappled shade for our crops during the main heat of the day. By growing some strategically placed trees in your garden you can create some cooler areas that are perfect for crops that are more prone to bolting during the hot summer months. Tree roots also help to improve soil structure. If you plant fruit trees you can also get another crop!
Keep Nitrogen Levels Down
By feeding your soil, rather than your plants you can manage the amounts of nitrogen in your soils. To be able to grow fast and set seeds quickly plants must have access to plenty of nitrates in the soil. These are available in large numbers in liquid fertilisers. In well balanced soils there will also be nitrates, but not in such high amounts meaning that fast growth and seed formation are not so easily achieved by our plants.
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