With the rapid greening of the landscape, as bud burst really gathers pace, it’s easy to be lulled into a false sense of security this month. It’s still perfectly possible to get falls of snow in April and clear skies overnight generally result in big temperature drops and damaging frosts. Tender bedding plants have been on display in garden centres for many weeks but these are only really viable if you are able keep them frost-free in a heated greenhouse or have room indoor on your windowsills. If you are able to protect them for a few more weeks, until the infamous “after the last frost”, then buying your tender plants as tiny plugs is very cost-effective as long as you are able to mollycoddle them for a while and pot them on a couple of times before their final planting out.
It’s not too late to sow some bedding plants and gap fillers now with the advantage that later sowings are not so dependent on supplementary heating because warmer outside temperatures, with longer days, mean that glasshouses and coldframes can get relatively balmy for a lot of the time. They will need some form of heating to prevent young seedlings from getting checked, even killed, by low overnight temperatures but simple heated propagators, or heat mats, will suffice for small-scale sowings.
If you did get sowing as early as February or March, there will be plenty of ‘pricking out’ and ‘potting on’ to be getting on with. If you sowed your seeds ‘en masse’ it’s important to prick them out into individual cells, or very small pots, before they get too congested and too large to successfully transplant. Wait until they have produced their first ‘true leaves’, these will be the same shape as the mature leaves but on a miniature scale, but also still have their ‘seed leaves’, the ovoid leaves that emerge upon germination, because it’s best to handle the tiny seedlings by holding these relatively tough seed leaves, rather than the fragile stem or true leaves.
In most cases seed raised plants will require at least one more ‘potting on’ before they reach an adequate size to be used in the garden, hanging basket or bedding scheme. It’s important to use fresh potting compost to do this because it will have been formulated with the right amount of nutrients to sustain the growing seedlings and it will be sterile, free from weed seeds, pests and pathogens, to give your delicate new plants the best chance of survival.
It’s tempting to pot a tiny seedling into a relatively large pot in order to give it ‘room to grow’. This is not a good idea because a large pot, with virtually no plant roots in it, is very likely to become waterlogged, and the compost anaerobic as a result, which in turn causes the fragile new roots to die and the seedling to ‘rot off’. There is a reason why buying a fully grown plant is relatively expensive compared to a tiny ‘plug plant’; a lot of work and resources has gone into producing it.
Some other gardening tasks to be getting on with; spring flowering bulbs should be allowed to die down naturally although a sprinkling of ‘blood, fish and bone’, gently forked in around them, will help to build up flowering strength for next year. The patches in beds and borders where spring bulbs have died down are prime spots for the tender bedding plants that you have just been pricking out and growing on. By the time that any chance of frost has passed, as mentioned previously, early spring bulbs should have completely died down and, as long as the bulbs have been planted suitably deep, your summer gap fillers can be planted in the vacated space.
One of the joys of April are the early flowering perennials which are the kind of plants which have evolved to come into flower at almost exactly the same time as their leaves emerge in the spring in order to steal a march on all those perennials which will later overshadow them and flower on taller stems. The kind of plants that I’m thinking of are the primulas, Brunnera, pulmonarias and Dicentra which can be planted as a kind of carpet or tapestry, either as a feature on their own or under shrubs. Primulas and pulmonarias, the lungworts, are particularly useful in happily seeding around and frequently producing seedlings with attributes different to their parents if you have more than one type of Primula or Pulmonaria in your garden.
It’s a good time to plant out containerised trees, shrubs and herbaceous perennials as they are in active growth, which makes establishment easier, and water is in good supply. It’s good practise to water in all new plantings, even in wet weather, because this initial watering in is to ensure an intimate bond between the newly introduced root ball and the surrounding soil. Further watering, in dry spells, remains essential for the whole establishment period at least—the prolonged dry period last year claimed many victims as it occurred before full establishment had taken place.
Although the time window for bare-root planting is now over, the flipside is that now is the real window of opportunity for planting evergreens. They need to be planted after any freezing winter weather has passed and before the risk of summer heat and drought is upon us. This is because, being evergreen, they are unable to shed their leaves and are therefore always losing a certain amount of water from their foliage which needs replacing via root uptake.
When the ground is frozen, or droughted, there is no water available to the roots and the evergreen plant will become stressed; in severe cases it will die. Moving or planting them at this time of year means that they are active enough, after the relatively dormant winter months, to produce new roots ensuring rapid establishment and to have at least some resilience to drought. Having said that, a thorough watering-in at planting time is essential as is the ability to keep them watered throughout at least the first growing season.
Maybe now is a good time to treat yourself to a few more water butts, hoses and well pumps? “Fail to prepare; prepare to fail” and all that!
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