Action plan: Nigel Colborn's essential jobs for your garden this week

  • This is a good time to refresh compost if you grow camellias or azaleas in containers
  • After such a dry spring, raspberry crops could become stressed. To prevent that, sprinkle fresh lawn-mowings between the rows of canes and around the plants
  • If you grow asparagus, you’ll be harvesting spears now. There may be weeds, too — so deal with those as you go

This is a good time to refresh compost if you grow camellias or azaleas in containers. 

Ericaceous compost loses acidity — especially when hard water is used — and that could compromise the health of your plants. 

With care, remove the top layer of the growing medium without major root disturbance. Replace what you took with fresh ericaceous compost, firming it gently. 

This is a good time to refresh compost if you grow camellias or azaleas in containers

This is a good time to refresh compost if you grow camellias or azaleas in containers

As an extra precaution, I mix a tablespoon of yellow sulphur to the mix, along with slow-release fertiliser. 

Keep azaleas and camellias well-watered, using rainwater whenever possible. 

As an alternative to using slow-release fertiliser, you can feed with dilute solutions of liquid plant food every ten to 14 days until the new shoots have matured.

MULCH RASPBERRIES

After such a dry spring, raspberry crops could become stressed. To prevent that, and to boost soil health, sprinkle fresh lawn-mowings between the rows of canes and around the plants making a thin mulch. 

Fresh-mown grass is rich in nitrogen and other nutrients. As it decomposes, these will help feed the crop. Never use mowings from lawns treated with selective weedkiller. 

After such a dry spring, raspberry crops could become stressed. To prevent that, and to boost soil health, sprinkle fresh lawn-mowings between the rows of canes and around the plants making a thin mulch

After such a dry spring, raspberry crops could become stressed. To prevent that, and to boost soil health, sprinkle fresh lawn-mowings between the rows of canes and around the plants making a thin mulch

WEED ASPARAGUS 

If you grow asparagus, you’ll be harvesting spears now. 

There may be weeds, too — so deal with those as you go. Annuals such as groundsel and red deadnettle are easy to pull out. 

Perennials — bindweed, creeping thistle, nettles etc — are more damaging and difficult to remove. 

You can destroy them with glyphosate (Roundup), but take great care. The herbicide must be sprayed or painted directly onto individual weeds. 

A drop of glyphosate on an asparagus spear could damage or kill the whole plant. Before spraying, check that no shoots remain above ground. 

If you accidentally spray glyphosate onto a nontarget plant, hose it down copiously at once. 

Water will wash away the chemical before it has been absorbed by the plant. 

If you grow asparagus, you’ll be harvesting spears now. There may be weeds, too — so deal with those as you go. Annuals such as groundsel and red deadnettle are easy to pull out

If you grow asparagus, you’ll be harvesting spears now. There may be weeds, too — so deal with those as you go. Annuals such as groundsel and red deadnettle are easy to pull out

PLANT OF THE WEEK: HONESTY LUNARIA ANNUA

Common it may be, but Honesty has enormous garden value. 

The strident purple — or sometimes white — flowers of Lunaria annua are carried on branched stems above large leaves whose margins are serrated. 

As they ripen, the seed pods become translucent. 

Eventually, the seeds become visible through the tissue, earning the plant its name, — Honesty. 

There are strains with variegated leaves. Sought after Chedglow has dark leaves and purple-maroon flowers. 

Honesty thrives in almost any soil in sun or partial shade and is self-sowing. 

Common it may be, but Honesty has enormous garden value. The strident purple — or sometimes white — flowers of Lunaria annua are carried on branched stems above large leaves whose margins are serrated

Common it may be, but Honesty has enormous garden value. The strident purple — or sometimes white — flowers of Lunaria annua are carried on branched stems above large leaves whose margins are serrated

YOUR QUESTIONS

I’m growing sweet peas for the first time and want to achieve high quality blooms. How do I train them for that? 

G. Simms, Oxfordshire. 

Grow them as cordons. Line out your plants 30cm apart and train each up a single, tall cane. 

Begin by tying the strongest stem of each seedling gently to the cane. Remove all other shoots. 

As each stem extends, remove the tendrils without harming the leaves and pinch out any side-shoots. 

Keep each stem secured to its cane using jute string or re-­usable metal sweet-pea rings. Rings are available from crocus.co.uk and other suppliers. 

Pick the flowers as soon as they open. Never allow blooms to mature or run to seed on the plants. 

Don’t worry if the leaves become over-sized, as that’s normal for cordon sweet peas. 

To train sweet peas, grow them as cordons. Line out your plants 30cm apart and train each up a single, tall cane. Begin by tying the strongest stem of each seedling gently to the cane. Remove all other shoots. As each stem extends, remove the tendrils without harming the leaves and pinch out any side-shoots

To train sweet peas, grow them as cordons. Line out your plants 30cm apart and train each up a single, tall cane. Begin by tying the strongest stem of each seedling gently to the cane. Remove all other shoots. As each stem extends, remove the tendrils without harming the leaves and pinch out any side-shoots

Nigel Colborn's essential jobs for your garden this week

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