Your garden is a demanding beast which stops for no one

Your garden is a demanding beast which stops for no one

I hope that all are well rested and have enjoyed this summer and have had a chance to get away and relax?  However, as you all know the garden is a demanding beast and I’m afraid won’t stop for anyone!  This summer has seen some rather hot and balmy days and also the odd thunder storm, playing havoc with watering duties.  Only just the other day I was watering tubs and containers in the rain!  It just wasn’t enough to rely on mother nature; I had to boost the supplies.  That aside, other than watering and liquid feeding on a regular basis, there are just a few other jobs that shouldn’t be left too long.

This is the perfect time to look through the myriad of seed and bulb catalogues streaming through the post for colour ideas this autumn and importantly early next year.  Don’t just look out for decorative interest, which is important, but sometimes so is disease resistance especially for any edibles.  With perennials I’m also looking for those plants that are self-supporting  –  I just don’t want to deal with link stakes or canes everywhere.

One of the things I love to do is grow on lilies in pots and secrete them in the bed and borders as a form of successional bedding.  They’re ideal for giving height, instant colour and scent by the bucket load, however, once blooms have faded, they need to be removed and popped at the back of the garden to die down naturally; don’t forget to water though and feed to enrich the bulb for next years display.

Grow lilies in pots and put them into beds and borders

Grow lilies in pots and put them into beds and borders

Unfortunately you now have gaps…what’s to do?  Why not plant up slightly taller pots with perennials such as Rudbeckia, Echinacea and or varieties of grasses.  All of these flower well, but also improve with age…don’t we all!

Rudbeckia and Echinacea have fab flowers, but have even better autumn and winter colour with their superb deep black seed heads – very striking.  Grasses, on the other hand, produce flowers that are almost everlasting plus have foliage that colours well as it ages (they don’t need to be cut down until February next year). Doing this will extend the season of interest and keep your garden a talking point with friends and family.

Start to collect seed from plants.  Recently I collected spent flower stalks of Aquilegia vulgaris (columbine).  Harvest them carefully, because as soon as you touch the stems the seed falls.  Cut flower stems down to the base of plant or to an outward facing leaf and turn carefully into a large paper bag… and let nature take its own course.  Once seed has dropped sieve to separate any coatings etc from the seed.  Once complete seed can be stored in a clean envelope, labelled and dated, and stored in a frost free dry place.  Believe it or not I use the fridge, as long as its around 5°C (41°F), as this will ensure that viability is retained for as long as possible.  Use as and when required.  Aquilegia can be sown fresh in seed trays and left in cold frames or kept away from over exposed areas.  Sometimes they germinate early, if so keep them moist, NOT saturated, and allow them to grow on for at least ½ year.  This will enable a more stocky plant to develop.  Pot up and grow on for another ½ year before setting out into the ground.  Failing this you can also sow in February.  Plants will be ready to be move on early/ late summer.

Check out this RHS link to collecting, storing and sowing a range of seed

I can’t believe it another year has gone by and we have started another academic year at Writtle University College – notice the name change?

Check out the college web site for a full update

If you’re looking to update your knowledge and skills or wishing to pursue a career  in horticulture give the team a call on 01245 424200.  Alternatively, come and chat with us anytime.  Check out this link for further details

Good luck and happy gardening!

For any gardening tips why not contact Tom Cole, Senior Horticultural Lecturer, Writtle College, Chelmsford, CM1 3RR by post (including a SAE) or by email at

It is best to water first thing in the morning and later in the day

It is best to water first thing in the morning and later in the day

Goodness, as I write this, it’s hot out there!  Having watered already earlier today…I’m at it again, especially with my tomatoes, peppers and fruit bushes. Best to water first thing and again at the end of the day, hopefully standing pots on saucers or trays to try and keep as much water around the base of the pot. I usually water at the end of the day as this is great for reducing evaporation.  However, if a plant looks like it’s wilting and suffering from drought in the day, then water it immediately.

Using the right amount of water is the most important aspect of a plant’s survival in dry conditions. Bear in mind that it is not just hot weather that can cause soil to dry out, windy weather can also have a detrimental effect.  Try to avoid watering plant leaves in direct sunlight because they can become scorched, particularly when they have hairy foliage. Why not, if you haven’t already, install a water butt in the garden to conserve water.

For those of you enjoying yourselves away from home it’s worth investing in an automatic watering system with a timer, adjust it to take hot and dry weather into account. I’d also move container plants into the shade if you are going away on holiday and no one is watering your plants; your plants will thank you for it.

If you’ve got trees and shrubs that have been planted in the last couple of years on lawns or in areas of rough grass have a circle of clear earth around them – this must be kept clear or grass will prevent essential moisture getting through. Mulching with bark or compost will help.

Elsewhere in the garden consider cutting back early flowering plants such as foxgloves, snapdragons, lupins and penstemons as they go over, cut back just those sections of the flower spike that have faded, taking care to leave any secondary laterals that may be growing. You may get a second flush of flowers. Others worth doing this to are those lovely, fragrant catmints, hardy geraniums and any hellebore that escaped an early prune. With hellebores, as you cut back flower spikes, take a look at the base of the plant for seedlings. Don’t lift them now; come back in the autumn and pop them on into 9cm pots using a soil based compost such as John Innes Potting Compost No. 2. Grow them on by the back of the house, in a cold frame or unheard greenhouse and planting out next spring.

Lastly, be safe in the sun

It’s not only plants that can start to flag in dry weather, if you are working in the garden in hot conditions, it is important to take the following precautions:

  • wear suntan lotion or sun block and top up often
  • work in the shade if possible, out of direct sunlight
  • wear a hat or headscarf…they’re all the rage at the moment
  • take regular breaks and have frequent non-alcoholic drinks

Good luck and happy gardening!

For any gardening tips why not contact Tom Cole, Senior Horticultural Lecturer, Writtle College, Chelmsford, CM1 3RR by post (including a SAE) or by email at

Mixed borders can give year round interest

Mixed borders can give year round interest

The season is far from over.  At Writtle University College, the seasonal bedding is really at its best this time of year.

Over the last few years we have tried to make it a little more sustainable by using plants that are self-supporting, cover the ground and so block out weed growth that doesn’t require lots of deadheading.  The same can be said for our mixed borders around the campus.

A mixed border may contain trees, shrubs, herbaceous plants and bulbs.  Modern gardens tend to be small and may be better suited to a mixed border that can give interest throughout the year.

For me the advantages of a mixed border are many:

  • Labour is expensive and it may be difficult to afford to maintain large areas of herbaceous plants.
  • Herbaceous borders do not provide sufficient all year interest so trees, shrubs, herbaceous plants and bulbs are all grown together in a mixed border to provide extra colour and interest.
  • Shrubs are used to give structure.
  • Flowering and fruiting shrubs can provide interest in winter and spring.
  • Shrubs grown for their foliage colour can provide an effective foil or backdrop.
  • Herbaceous plants add to the seasons of interest especially in a small garden, by providing flowers and foliage at times when shrubs may be less interesting.

There are a few disadvantages of a mixed border such as:

  • Mixed borders can be difficult to plan
  • A range of skills is needed as trees and shrubs have to be pruned
  • Mixed borders may suffer from trying to look interesting at all times of the year

So if you want to add a new border this year why not consider a mixed one.  Consider the following:

  • The soil must be fertile, and well drained, with plenty of organic matter and moisture.
  • The area should be free of perennial weeds, pests and diseases.
  • The site must be sunny and open, away from overhanging trees; otherwise the plants become drawn and do not flower well. This is less important for foliage plants.
  • The site should be sheltered so that the wind does not damage plants.

Start planning now and preparing for planting out later this autumn or early spring.  If you’re sprucing up and existing areas these times are ideal for lifting up key plants and dividing them.  This simple technique enables you to keep young plantlets and discard and compost poor growth.

As far as maintenance goes check out my simple steps to success:

Fertilisation – an annual application in spring of a balanced fertiliser such as Growmore @ 100 g/m² or blood, fish and bone @ 70 g/m²

Weeding – regular weeding will be required, particularly in the spring and early summer

Staking – this is best carried out before required.  Materials used range from pea sticks, or lengths of hazel coppice, to bamboo canes and metal linking stakes.  Staking should be as unobtrusive as possible to allow the natural form of the plant to develop and should be 15-30 cm shorter than the ultimate height of the plant

Division – herbaceous plants require regular division to keep them floriferous and healthy.  This is carried out in the autumn or spring

Irrigation – irrigation may be necessary in prolonged dry periods or when plants are establishing.  Ground level irrigation systems such as porous pipes use water efficiently and do not damage flowers and foliage.  As with all irrigation a thorough soaking is preferable to a light sprinkling, in order to encourage plants to develop deep root systems

Dead heading – dead head where possible as this will encourage a longer flowering season

Pests and diseases – Monitor and treat pests and diseases accordingly.  Commonly occurring problems include aphids and powdery mildew.

Use this site for further information

Mulching – an annual application of a layer of leaf mould, well-rotted farmyard manure or garden compost helps to reduce weed seed germination and conserves soil moisture and improves soil structure.

Good luck and happy gardening!

For any gardening tips why not contact Tom Cole, Senior Horticultural Lecturer, Writtle College, Chelmsford, CM1 3RR by post (including a SAE) or by email at

Pricking out seedlings will give them more light and space to grow

Pricking out seedlings will give them more light and space to grow

If so it’s time to move them on to bigger and better things.  Once container-grown seedlings have germinated, it is usually necessary to prick them out.  This involves teasing out the seedlings and transferring them to a new container.

Why is pricking out necessary?
If seedlings are left to grow on in crowded conditions, they become drawn, with small leaves and long spindly stems and will never grow into good quality, sturdy plants. Pricking out will give seedlings more light, space and air making them less prone to fungal diseases.  At Writtle College most courses have been undertaking this task in readiness for summer bedding borders, vegetable plots and or trees and shrubs that were sown late last year.

The seedlings are transferred from a seed sowing compost to potting compost, which contains a higher level of nutrients than seed compost. Use a multi-purpose or a specific compost suitable for the plants you are growing on.

Broadcast seedlings may germinate erratically so that a range of sizes can be seen in the seed tray.  They can be graded during pricking out so that growth is more even.  Next time to avoid this try out modular trays – these contain cells of compost for individual seeds so there is no competition for water or nutrition.  As a result they can be left to grow for longer before moving to the next size pot.

Seedlings are spaced out so that they grow at a uniform rate.  This should mean that all the plants will be ready at the same time.

When should pricking out be done?
Basically as soon as possible! The seedling should have leaves that are large enough to handle and a simple, single, short root that will not be damaged by transplanting.  Another indicator is when seed leaves are touching.

Working area
Pricking-out should be undertaken either in a purpose-built, clean pricking-off shed or in the glasshouse beside the area where the containers of pricked-out seedlings are stood down. I haven’t any of these so I have ‘borrowed’ the dining room table and often use the draining board much to the consternation of my partner!

Gather all the necessary equipment and organise the workspace so it is both comfortable and efficient.

Choose a suitable potting compost such as loam-less potting compost (peat or coir potting compost) or J I No. 1 potting compost.  Never re-use potting compost for fear of disease.

Containers used range from seed trays to modular trays or pots depending on the seedling.  Today seed trays are less popular and modular trays are more common.  Containers must be clean to prevent the spread of fungal disease.

A striking off board is used to remove excess compost and boards that mark the pricking out stations are sometimes useful.  They may be bought but maybe made with two pieces of wood and nails spaced at regular intervals.

A dibber (a length of bamboo cane or a proprietary one) is used to tease out the seedlings.

Prepare the container by filling with compost and strike off the excess.  Modular trays should be tapped to settle the compost.

If pricking out into a tray an adapted striking off board may be used to mark out the planting stations.

Prepare the seedlings by watering in advance to ensure the compost is moist when you come to prick out the seedlings.  Ideally the seedlings should not be wet when you prick them out as this will make them more susceptible to damage.

Tap the tray of seedlings to loosen them from the sides.

Prick out the seedlings by:

  • Loosen the compost with your dibber and holding the seedling by the leaf gently tease it out of the compost
  • Make a hole in the compost using your dibber and insert the seedling into the hole.  Gently firm the compost around the seedling

Remember – never pick up a seedling by the stem, as this will cause damage.  Always pick up seedlings by the leaf using your thumb and forefinger.  Do not delay inserting the seedling into the compost as they dry out very quickly.

Most seedlings are pricked out individually but some seedlings such as Alyssum and Lobelia are pricked out in clumps of up to five seedlings.

Gently firm the compost around the seedling.  The seed leaves should sit just above the compost – if the seedling is left very tall it will not produce a sturdy plant.

Water the seedlings in, place the container in a warm environment to grow on (18– 20 °C), and protect from strong sunlight.

Keep a careful eye on watering and check regularly for pests and diseases.

Hardening off
Reduce the growing on temperature and eventually move the seedlings outside to covered cold frames.  Increase the ventilation during the day and eventually leave the lights (wooden framed glass panes used to cover cold frames) off at night.  Protect the seedlings by covering the lights with straw or newspaper should frost be forecast.

Good luck and happy gardening!

For any gardening tips why not contact Tom Cole, Senior Horticultural Lecturer, Writtle College, Chelmsford, CM1 3RR by post (including a SAE) or by email at

Hand-weeding is a practical way of removing weed

Hand-weeding is a practical way of removing weed

Weed control in horticulture generally falls into two main categories:

  • Cultural and mechanical methods
  • Chemical methods

Prior to controlling any weed it is important to establish whether it is an annual or perennial, as this will influence the control measure.

Annual weeds
It is important to prevent annual weeds from producing seed as the large numbers of seeds may germinate for years to come.

Effective control of annual weed seedlings can be achieved by hoeing on a dry, sunny day as they will shrivel on the soil surface, and need not be cleared away.  Larger weeds can also be treated in this way but it may be necessary to rake them off the soil surface.

A contact herbicide is sufficient for annual weeds.

Perennial weeds
Perennial weeds are more problematic as they can persist in the soil, re-establishing themselves from small portions of root or stem. Although they should also be prevented from going to seed it is the difficulty of ensuring that all parts of the plant are removed that is the main challenge.

Hand weeding is satisfactory for some perennial weeds such as Urtica diocia (perennial stinging nettle) and Taraxacum officinale (dandelion), but infestations of plants such as Convolvulus arvensis (bindweed) and Aegopodium podagraria (ground elder) may be made worse, as roots may be broken into several pieces, each piece capable of producing a new plant.  Mechanical soil cultivation will spread root fragments, allowing these weeds to further establish themselves.

A translocated herbicide may be required for control of perennial weeds.

However, there are other methods of controlling problematic weeds:

In early spring apply a mulch 10cm (4”) thick of weed-free, organic material such as leaf mould or processed bark to help prevent weed seeds germinating and to smother weed seedlings.  Do not use partially decomposed garden compost or manure as they often contain weed seeds… unless you’re happy weeding this to!

Established perennial weeds may grow through the mulch but as they tend to root into the loose material they are easier to remove.

Organic gardeners use a technique called sheet mulching – this involves mulching an area with material such as carpet for a year or more to control perennial weeds.

Why not try weed mats
This woven plastic sheeting can be laid directly over the soil.  It will prevent annual weeds from establishing and problem weeds such as Convolvulus arvensis (field bindweed) are both less likely to grow if the area is covered for at least two seasons.  Cover the sheeting with bark chip mulch to improve its appearance.  Weed mat is particularly useful in fruit and vegetable gardens.  Slits can be made in the sheeting through which the crops can grow.

Better still, hand-weeding and hoeing
Hand-weeding, hoeing and forking are often the only practical ways of removing weeds in flower beds, the vegetable garden and small patches of ground where weed killers cannot be used safely without risk of harming nearby garden or crop plants.

Small patches of perennial weeds may be forked out but great care must be taken not to leave in the soil sections of rhizomes, roots, or bulbils that will grow again.  Check a month or so later and remove any re-growth.

Hand-weed or hoe in dry weather, if possible, so that the weeds are easily loosened from the soil.  In wet weather remove uprooted weeds from the site to prevent them from rooting back into the soil.  Hoe only lightly around cultivated plants to prevent their surface roots from being damaged.

Mechanical weed control
Market gardeners often use rotary cultivators with hoeing or cultivating attachments for annual weed control between rows of vegetables but they may be unsuitable for perennial weeds, as they simply cut the rhizomes of weeds such as couch grass.

Back to chemical weed control
All chemicals used to control weeds are referred to as herbicides.  They are usually formulated as liquids, wettable powders or granules, depending on the product and its application.

Herbicides are categorised into two main groups:

Total herbicides
Total herbicides will kill all plants they come in contact with.  They must only be used where total weed control is required.

Selective herbicides
These are chemicals that have an ability to control certain groups of weeds e.g. broad-leaved weeds growing in turf, whilst at the same time leaving desired plants undamaged.

Mode of action of herbicides:

These products will kill the parts of the plant that they come into contact with.  They are effective at controlling weak rooted annual weeds.  However, perennial weeds with stronger root systems will re-grow.

These products will be absorbed by the foliage and translocated to the weeds’ roots, killing all parts of the plants.  As a result they are very effective at controlling perennial weeds.

Soil acting (residual)
These herbicides are applied directly onto the soil with the intention of preventing weeds from germinating.  For this reason they are often referred to as pre-emergence herbicides.

They form a layer of chemical in the upper topsoil, above the established ornamental plants’ roots but to a sufficient depth to control weed growth.

If using pesticides take care to read the label and follow instructions to the letter to avoid contamination of yourself, others and importantly the environment.

Good luck and happy gardening!

For any gardening tips why not contact Tom Cole, Senior Horticultural Lecturer, Writtle College, Chelmsford, CM1 3RR by post (including a SAE) or by email at