When to plant vegetables in their final growing position is not something that is an exact science, as there will always be some variable.
Following the advice on the seed packet or a diary or chart will help keep you on track with sowing seeds, but how quickly your seedlings grow, and when the climate is perfect for them to be transplanted are things that will always vary.
If you are germinating seeds in a propagator or on a windowsill there is often a temptation to start thing s off early. Although this practise can reward you in a year with a warm spring, when winter seems to not want to leave us you can be left with quite a seedling management problem.
One of the first issues of vegetable plants in pots is the conditions under the soil, this is because the secret to a strong high yielding vegetable plant is in its roots, and without a sound root structure your vegetable plants will not do well.
Rule one is do not let your vegetable plants get pot bound.
A lot of roots growing through the bottom of the pot are often the first signs you see that the plant is becoming pot bound, so keep checking the underside of your vegetable plants.
Although the appearance of these roots is no a definitive sign that the plant needs to be moved to a bigger pot or put into its final growing position, it is worth doing so anyway so that you’ll avoid any damage and you’ll get an opportunity to check the root structure.
The picture above is of a mange tout plant that has been left in the pot to long. The characteristic of a pot bound plant shows a rotating root structure that you need to disturb by loosening the roots to try to break this rotating growth.
However some vegetable will not stand their roots being disturbed, so it’s best to avoid them getting to this state by checking and potting on if needed.
If your plants are ready to go into their final growing position, knowing when to plant vegetables outside is worth checking out. Some vegetable plants are very susceptible to frost and if you plant out too early and you have an unexpected late frost, then you will most likely lose these plants.
It’s worth knowing the final frost date for your area so you can estimate the likelihood of having a late frost. The map on the left gives the historical final frost dates for the UK, click on the image to enlarge it in a new window.
But regardless of frost dates, when to plant vegetables is more than just understanding climate. Young plants are fragile and any sudden change in conditions could shock them, or even kill them.
This is why you need to harden them off, as moving them from a propagator to outdoors will do them no good at all.
Hardening off is about acclimatising your seedlings to their new location. Normally we would start the process by turning the propagator off during the daytime, then after about a week we would move them to a warm windowsill, before positioning them in a cold frame to get used to the lower outside temperatures.
Finally we would plant them into their final growing location.
Here are some tips to help you to know when to plant vegetable seeds, as well as a seed planting wall planner to help keep you on track.
Visit this page for some more growing vegetables ideas.