What a dry few months it has been, and I know I will be looking to make changes in the way I garden to accommodate the change of weather. Perhaps it will mean that cottage gardens as we know them will not survive and we will all have to look at different groups of plants that are suited to hot dry summers they will be different but just as attractive.

Jobs to be done in September:

Dividing Perennials

Dividing perennials regularly will ensure healthy, vigorous plants that will perform year after year. It also offers the opportunity to multiply your plants.

When to divide perennials

Plants can be divided successfully at almost any time if they are kept well-watered afterwards. However, division is most successful when the plants are not actively growing.

  • Divide summer-flowering plants in spring (Mar-May) or autumn (Sep-Nov) when the soil is dry enough to work. In wet autumns, delay until spring. Spring is also better suited to plants that are tender
  • Many spring-flowering plants, such as irises, are best divided in summer (Jun-Aug) after flowering when they produce new roots

How to divide perennials

Here are our simple tips for dividing but do please check a gardening book or the labels on plants before starting this process.

  • Some plants, such as Ajuga (bugle), produce individual plantlets which can simply be teased out and replanted
  • Small, fibrous-rooted plants such as Heuchera, Hosta and Epimedium can be lifted and pulled apart gently. This should produce small clumps for replanting
  • Large, fibrous-rooted perennials, such as Hemerocallis (daylily), require two garden forks inserted into the crown back-to-back. Use these as levers to loosen and break the root mass into two sections. Further division can then take place
  • Plants with woody crowns such as Helleborus or fleshy roots such as Delphinium  require cutting with a spade or knife. Aim to produce clumps containing three to five healthy shoots
Hermerocallis

Aftercare

Plant as soon after division and water them well. They can either be replanted in the same spot,  taking the opportunity to mix in a little garden compost.

Perennials needing different methods

Here are three plants that require a different method of division.

Crocosmia and Dierama

  • Divide Crocosmia and Dierama in spring
  • To remove the corms without damage, dig down 30cm (1ft) to avoid and gently lift
  • The roots of both perennials form ‘chains’ of corms, which can be replanted intact or individually separated. There is evidence that maintaining the ‘chains’ intact may be the better option
  • Discard wizened or diseased corms and trim old leaves
  • Replant sections at their original depth
Crocosmia

It is worth noting that crocosmias flower profusely when crowded, so do not divide clumps too often – every two or three years should be enough.

Dieramas dislike disturbance and will take time to flower again after division.

Hostas

  • Lift and divide clumps of hostas in spring or late autumn
  • Hostas with tough, fibrous roots can be divided with a sharp spade, slicing the clump in two
  • Large clumps can be split further to leave sections containing five or six shoots
  • Cultivars with loose, fleshy roots are best teased apart by hand or with two hand tools by placing them back-to-back to lever them in two
  • Plant the divided sections at their original depth, with the shoots above the soil surface

Ensure that plants don’t dry out while they do re-establish, and check slugs and snails are not attacking your plants.

Hostas

Bulbs: planting

Bulbs make a wonderful display planted in containers or borders. Planning and purchasing of the bulbs start in August/September.

When to plant bulbs

Autumn

  • Plant spring-flowering bulbs  including daffodils, tulips, crocus and hyacinths, preferably by the end of September
  • Plant tulips in November or even up to mid-December
  • Plant hardy summer-flowering bulbs, such as lilies, alliums and crocosmia, in September and October

Most hardy bulbs, including tulips and daffodils, prefer a warm, sunny site with good drainage as they come from areas with dry summer climates.

Daffodils

How to plant bulbs

Plant as soon as possible. Aim to plant in groups of at least six, as the more bulbs that are grouped together, the better the display. Typically, 25 to 50 bulbs may be needed to make an impressive show.

  1. Dig a hole wide and deep enough for your bulbs. Plant most bulbs at two to three times their depth. For example, for a bulb measuring 5cm (2in) high, dig a hole 10-15cm (4-6in) deep and sit the bulb in the bottom of it
  2. Place the bulbs in the hole with their ‘nose’, or shoot, facing upwards. Space them at least twice the bulb’s own width apart
  3. Replace the soil and gently firm with the back of a rake. Avoid treading on the soil as this can damage the bulbs
  4. If the ground is moist or the bulbs are autumn-planted, watering is not critical. Otherwise water straight after planting

Water collecting and storage

Plants need the most water in hot, dry and windy weather, which is usually when water companies are least able to meet demand. Plants are most vulnerable to shortages of water when they are first planted when their roots have not yet established into the deeper, moister layers of soil.

Water is a precious resource and  for gardens mains water should be used as sparingly as we can. Plants don’t need perfectly clean water. A significant amount of energy and treatment are used to provide safe water to our homes so using stored rainwater or grey water in your garden also lowers our carbon emissions. 

Rainwater is also better for your plants as it often has a lower ph. The minerals that are sometimes found in mains water, especially in hard water areas can raise the pH of your root zone, which can affect the nutrient availability. Rainwater is especially good for ericaceous plants such as azaleas.

Collecting rainwater

Rainwater can be collected from the roofs of homes, garages, greenhouses and other garden structures as long as they have gutters and a down pipe that enters the drain at ground level.  Position the rainwater butt in the shade if you can, as the water will be kept cooler, reducing the growth of bacteria.  It is advisable to clean water butts out annually.

Deadheading

Finally keep deadheading as the late season of flowers can be kept going a little longer by cutting off the faded blooms. This works for the late flowering perennials such as aster, heleniums and salvias which will keep providing colour for some time.